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Beta is gone

By: JeffMasters, 2:57 PM GMT on October 31, 2005

The heavy rains have ended in Nicaragua and Honduras. Hurricane Beta is no more, reduced by Nicaragua's high mountains to a remnant swirl of low clouds over El Salvador.
Beta's passage over Nicaragua dropped rains of up to ten inches in some areas; the highest precipitation amounts reported by official measuring sites were 9.5 inches at Chinandega in western Nicaragua and 6 inches at Rio Sulaco in the mountains of Honduras. Up to 120 houses were reported destroyed in coastal Nicaragua where Beta made landfall, and flooding in the Honduran fishing town of Iriona caused residents climbed to climb onto the roofs of their homes to escape the high waters. No deaths have been reported in either country, and it appears that Beta was too small to trigger the heavy rains required to cause a major disaster. The National Hurricane Center will probably not have to retire Beta's name from the list of Atlantic hurricanes.

Beta's remains will emerge out over the Pacific today, and may re-intensify into a tropical storm. However, any storm that might form is expected to move quickly away from Central America, and no heavy rains or high winds will affect land areas from this system.

Elsewhere in the tropics
A tropical disturbance located about 200 miles south of Puerto Rico is suffering significant wind shear from an upper-level low pressure system near Haiti. This shear will prevent any development from occurring today. On Tuesday, this upper-level low is expected to weaken, and some development of the disturbance is possible as it continues west towards Hispanolia and Cuba.

Some remnants of Hurricane Beta's moisture remain in the southwest Caribbean just north of Honduras, and this area may have to be watched later in week for possible development.

I'll be back with an update Tuesday morning.

Jeff Masters

Beta hits Nicaragua

By: JeffMasters, 4:11 PM GMT on October 30, 2005

Hurricane Beta smashed ashore on the central coast of Nicaragua at 7 am EST this morning as a Category 2 hurricane with 105 mph winds. Beta put on an impressive burst of intensification last night and had 115 mph winds for about six hours before weakening substantially just prior to landfall. This brief burst of intensification made Beta the seventh major hurricane of the 2005 season. This is one hurricane shy of the record of eight major hurricanes seen in 1950.

Beta probably brought a 15-foot storm surge to the coast, plus 100 mph plus winds in a small area up to 15 miles from the center. The east coast of Nicaragua is sparsely populated, and these winds and the storm surge probably only affected a small number of people. However, Beta's rains will cause serious flooding and mudslides over Nicaragua and Honduras the next two days as the storm moves over the mountains of western Nicaragua and dissipates. Beta may end up being Nicaragua's fourth worst hurricane of all time, behind Hurricane Joan of October 1988, the great 1605 hurricane that killed over 1300, and Hurricane Mitch of 1998. Joan killed 148 people in Nicaragua, with the large death toll blamed in part on the residents' resistance in the coastal town of Bluefield to evacuation.

Honduras will also suffer Beta's wrath, but is missing the core of Beta's moisture and will very likely avoid the kind of serious flooding that killed thousands during Hurricane Mitch of 1998. Tune into wunderblogger Helen's blog from Roatan Island, Honduras, to follow the storm. Roatan is on the central coast of Honduras--the area Hurricane Mitch hit hardest.

Beta is probably too small to emerge out over the Pacific and re-intensify into a tropical storm. Hurricane Joan did successfully make the crossing, to be reborn as Hurricane Miriam in eastern Pacific. However, Joan was a large and fast-moving Category 4 hurricane. Beta's remains should bring no more than 3-6 inches of rain to El Salvador, Costa Rica, and Guatemala over the next few days.

Elsewhere in the tropics
The large tropical disturbance in the central Caribbean that was interfering with Beta's circulation yesterday has weakened and has been partially absorbed by Beta. This disturbance is not expected to develop.

A large tropical wave located about 200 miles east of the Lesser Antilles has not become better organized today but has some potential for further development over the next few days as it moves west or west-northwest at 15 mph. This area of disturbed weather will bring heavy rain and gusty winds to the northern Leeward Islands today. If a tropical storm does develop from this wave, it could threaten Hispanolia, Cuba, Jamaica, and the Bahamas later in the week. Wind shear over the Caribbean is expected to remain low the next week, favoring tropical storm develoment of any tropical waves that traverse the region.

I'll be back with an update Monday morning.

Jeff Masters

Hurricane Beta: unlucky 13

By: JeffMasters, 3:03 PM GMT on October 29, 2005

The Hurricane Season of 2005 is determined to own every major record for the Atlantic, and now has another--Beta is the 13th hurricane of the season, beating the record of 12 hurricanes set in 1969. Number thirteen will be an unlucky number for both Nicaragua and Honduras, who figure to bear the worst of this strengthening hurricane. In one respect, though, these countries have been lucky--the tropical disurbance that formed northeast of Beta yesterday is still there today, generating wind shear over Beta that is keeping it from rapidly intensifying. Had the disturbance not formed, Beta would already be a Category 2 hurricane today, and well on its way to a Category 3. As it is, the disturbance is still generating about ten knots of shear over Beta, which has allowed only a slow rise to Category 1 strength.

The disturbance has steadily weakened the past 24 hours, and so has the shear over Beta. By the time Beta makes its expected landfall near the Nicaragua-Honduras border Sunday morning, the shear will drop to five knots, which could allow rapid strengthening. There is not much time, though, for Beta to make it to Category 3 status, and the most likely strength at landfall is as a Category 2 hurricane. However, the latest microwave satellite data from NASA's TRMM satellite shows a pinhole eye--a very small 10-mile diameter eye like Wilma developed just before her rapid deepening phase. This may portend a rapid intensification cycle to Category 3 strength or higher may occur today. The hurricane hunters will be in the storm beginning at about 3 pm EDT today to check on its strength.

The island of Providencia (Columbia) received a direct hit from Beta last night and experienced sustained hurricane force winds for many hours that caused serious damage. Communications with the island were cut off at the height of the storm and have not been re-established.

The computer models are sorely missing the presence of the NOAA jet to provide detailed data on Beta's surrounding environment. Only one of the four main models--the UKMET--has correctly forecast the slow north and then northwest drift of Beta. The other three models have incorrectly been assuming the ridge to Beta's north is much stronger than it really is. The resulting forecasts of a westerly or southwesterly track across Nicaragua and into the Pacific Ocean have been incorrect for three days in a row. All indications are, though, that this ridge is unusually strong for this time of year, and Beta is not likely to turn north and threaten Cuba or Florida, at least for the next three to five days. The official NHC forecast seems reasonable.

If Beta does make landfall near the Honduras/Nicaragua border as a Category 2 storm as expected, a large storm surge of up to 15 feet is expected, since a long shallow area of Continental Shelf waters exists close to shore that will allow the storm surge waters to pile up. One would expect such a large storm surge, plus Beta's 100-mph sustained winds, to cause tremendous damage--but this is a large and very sparsely populated rainforest region. The storm surge and winds are unlikely to do significant damage. Far more dangerous will be Beta's rains, which may push inland into the mountainous regions of central Honduras where Hurricane Fifi in 1974 killed 8000, and where Hurricane Mitch in 1998 killed over 9000. Rains of up to 0.8 inches/hour are alreay affecting northeast Honduras, and Beta's slow motion will allow it to dump up to 15 inches of rain in some regions of Honduras. However, Beta is a very small storm, and its rains will affect a smaller portion of Honduras than either Fifi or Mitch did. Plus, Mitch dumped at least 30 inches of rain over much of Honduras during its rampage. These factors, along with the improved evacuation procedures that have been adopted in Honduras since 1998, give hope that Beta will not trigger a major flooding disaster in Honduras. Tune into wunderblogger Helen's blog from Roatan Island, Honduras, to follow the storm. Roatan is on the central coast of Honduras--the area Hurricane Mitch hit hardest in 1998.


Figure 2. Rainfall rate at 7:30 am EDT, taken by a NOAA polar-orbiting satellite. Image credit: Navy Research Lab.

Elsewhere in the tropics
The large tropical disturbance in the central Caribbean that is interfering with Beta's circulation has weakened and is not expected to develop through tomorrow.

A large tropical wave located about 600 miles east of the Lesser Antilles has become better organized today and has some potential for further development over the next few days as it moves west or west-northwest at 15 mph. This area of disturbed weather will bring heavy rain and gusty winds to the northern Leeward Islands on Monday and Puerto Rico on Tuesday. If a tropical storm does develop from this wave, it could threaten the Bahamas and the Southeast U.S. coast five or six days from now.

I'll be back with an update Sunday morning.

Jeff Masters

Beta drifting; Wilma revisited

By: JeffMasters, 2:22 PM GMT on October 28, 2005

Beta remains a tropical storm this morning, drifting slowly north off of the coast of Nicaragua. Its rise to hurricane strength has been thwarted by a large tropical disturbance that has developed about 300 miles to the northeast. This disturbance has created a layer of easterly winds on its south side at mid and upper levels. These winds are now generating about 10 knots of wind shear on Beta's east side. The shear disrupted the small eyewall that was forming early this morning, and Beta decreased in strength for a time. Deep convection has made a bit of a comeback this morning, but Beta continues to struggle with the shear, and has a long way to go before making hurricane status. The shear over Beta is expected to increase to 15 knots by tomorrow morning, then decrease back down to the favorable 5 knots we saw yesterday. Since Beta is a very small system, this relatively high shear may keep the storm from attaining hurricane status until Saturday afternoon or evening. We'll know better this afternoon at about 4 pm EDT, when the first hurricane hunter flight is scheduled to arrive.

Beta is stuck in an area of weak steering currents, and is being slowly pulled northwards by the trough of low pressure that swept Wilma over Florida. The computer models are now more divided. The GFS, NOGAPS, and GFDL models forecast that this trough will pull northwards and strand Beta in the southwest Caribbean. A weak ridge of high pressure will then build in and force Beta westward, with a landfall expected in northeastern Nicaragua. The UKMET model, plus some of the less reliable models we usually don't mention, like the Canadian, LBAR, and NHC98 models--favor a more northerly track, with Beta entering the western Caribbean after brushing northeastern Nicaragua. As we can see from the plot of historical tracks of October tropical storms in a similar location, this is the prefered track taken by similar storms in the past, and it would not surprise me if Beta ended up taking a similar path.


Figure 1. Historical tracks of October tropical storms near Beta's location. Only one out of seven of these storms hit Nicaragua.

If Beta does make landfall in Central America, it is unlikely to make it all the way across the rugged mountains of Nicaragua and arrive intact into the Pacific. Beta is a very small storm, and probably will not be intense enough or moving fast enough to survive the crossing. Crossing the flat Florida peninsula is no problem for a hurricane, but the high mountains of Central America can block a hurricane's low level circulation from the surface to 5000 feet, seriously disrupting it. Hurricane Joan of October 1998 did successfully make the crossing, to be reborn as Hurricane Miriam in eastern Pacific. However, Joan was a large and fast-moving Category 4 hurricane.

Although a small storm, Beta will bring 10-20 inches of rain over the regions of Nicaragua and Honduras it crosses, creating serious flooding situations. However, since Beta is a small storm, these rains will be confined to a realtively small area. If Beta hits the northeast corner of Nicaragua or Honduras, the terrain there is relatively flat, and major loss of life from flash flooding and mudslides will not result. Beta is small enough that it is not expected to affect Costa Rica and Panama, and shipping through the Panama Canal should be unaffected.

I know I said this in yesterday's blog, but it bears repeating since I get asked this question all the time: There are no provisions for what to do in the event we have to retire Beta's name and replace it on the list of hurricane names. One possibility is that the storm will be dubbed Beta-2005 and the name Beta will be reused. Another possibilty is that Beta will be skipped over next time the Greek alphabet comes into use.

Elsewhere in the tropics
The large tropical disturbance in the central Caribbean that is interfering with Beta's circulation has increased in organization this morning. Wind shear is a light 5 knots over the disturbance, and some development of this system is possible today. The disturbance is very close to Tropical Storm Beta, though, and Beta may end up absorbing the disturbance.

Elsewhere, tropical storm formation is not expected.

Wilma revisited
I will continue to link to wunderphotos that members in South Florida post this weekend as power is being restored, allowing people to at last turn on their computers and upload photos. As most of the media attention has been focused on Florida for this storm, I want to go back along Wilma's path and draw attention to some of the other areas affected.

Wilma's effect on Mexico
Officials analyzing the damage to Mexico now agree that Hurricane Wilma is the most destructive hurricane ever to hit Mexico, surpassing the $1.2 billion in insured property damage done by Hurricane Gilbert in 1988. Most tourist facilities in Cancun and surrounding areas are expected to be closed through mid-December, and economic losses from this closure alone will approach $1 billion. Officials estimate that 98 percent of the tourist infrastructure and 75 percent of the population of the state of Quintana Roo, which includes the resorts of Cancún, Cozumel, Playa del Carmen and Isla Mujeres, have been damaged. Over 90 percent of the 17.4 miles of sand in Cancún has been washed away, and a multi-million dollar beach replenishment project will begin in December. Cruise ships scheduled to dock at Cozumel are finding alternate ports of call, as one of that island's three piers for cruise ships was completely destroyed, and another heavily damaged. Cozumel also suffered "significant damage" to its famous coral reefs, the Environment Department said in a report. Over a million acres of forests were also damaged by Wilma, according to the report.

On a hopeful note, Mexico has shown a remarkable ability to bounce back quickly from severe hurricanes, as we saw after Hurricane Gilbert in 1988 and Hurricane Emily earlier this year. The bulldozers are already out on the beaches of Cancun, clearing away debris. President Fox's goal of having 80% of Cancun's hotels open for business by December 15 is ambitious, but doable. A full recovery by Easter seems probable. Cozumel may recover faster; officials there have set a November 15 date for resuming tourist traffic, and Carnival Cruise lines has agreed to change their return date for cruise ship visits from December 15 to November 15.

Wilma's effect on the Bahamas
The western end of Grand Bahama Island received the full force of Wilma's southeast eyewall when she was a Category 3 storm, and suffered significant damage. Up to 7,000 of the island's population of 47,000 were affected. Grand Bahama was also hard hit by September 2004's Hurricane Frances and Jeanne, and was not recovered from those storms. The communities of Eight Mile Rock, Hepburn Town, Hunters, Martin Town, and Pinder's Point suffered major destruction to homes and utilities from a 15-20 foot storm surge. The island of Bimini, which has a population of 1,717, also suffered significant damages to homes, trees and utility poles from heavy rains and storm surge.

Wilma's effects elsewhere
Torrential rains in southwest Haiti triggered flooding that killed 11 people there. Severe flooding in Jamaica caused millions in damages to roads and buildings and killed one person. Wilma's storm surge and 20-foot foot waves pushed flood waters six feet deep up to 700 meters inland in Havana, Cuba, flooding thousands of buildings and destroying portions of the famed Malecon seawall. Including the damage done by a week of heavy rains to both ends of the islands, Wilma damaged or destroyed over 5000 buildings in Cuba. Over 700,000 people were evacuated in Cuba at various times during Wilma's passage. Honduras, Belize, and the Cayman Islands all received flooding and wave damage from Wilma.

Tropical Storm Alpha
More people may have been killed by Tropical Storm Alpha than by Wilma. The death toll in Haiti stands at 17, and nine people were killed in the Dominican Republic, which shares the island of Hispaniola with Haiti. Most of the victims in the Dominican Republic were swept away when a river broke its banks in the northern province of Puerto Plata. In Haiti, the Interior Ministry said that four people were still missing, bringing the likely total death toll to 30. Wilma is being blamed for 27 deaths so far, 10 in Florida, and 17 people in Mexico, Haiti and Jamaica.

I'll be back with an update if Beta attains hurricane status today, otherwise I'll see you in the morning.

Jeff Masters

Beta on its way to hurricane status

By: JeffMasters, 3:46 PM GMT on October 27, 2005

The Hurricane Season of 2005 remains unrelenting. Tropical Storm Beta formed this morning over the warm ocean waters of the southwest Caribbean, just north of Panama. Given the ideal environment for intensification setting up in the southwest Caribbean, this is likely to become Hurricane Beta by tonight, and could grow to major hurricane status before making landfall in Nicaragua on Sunday.

Recent satellite imagery shows a small but rapidly developing system. There is plenty of growing deep convection, good low-level spiral banding, and a Central Dense Overcast (CDO) forming over the center. An eyewall appears to be forming under the CDO, and there is a good chance we'll be talking about Hurricane Beta by this evening. The first hurricane hunter flight is scheduled for Friday afternoon.

Beta is stuck in an area of weak steering currents, and is being slowly pulled northwards by the trough of low pressure that swept Wilma over Florida. All the computer models except the Canadian model forecast that this trough will pull northwards and strand Beta in the southwest Caribbean. A weak ridge of high pressure will then build in and force Beta westward, with a landfall expected in northeastern Nicaragua. With water temperatures 29 - 30C, very light wind shear less than 5 knots, the chances of Beta growing to major hurricane status appear good. Intensification beyond Category 3 status is questionable, since Beta is travelling over relatively shallow water with lower heat content than Wilma had to work with. Additionally, Beta's slow forward speed may cause some upwelling of cold water from the depths that will interfere with the intensification process.

Beta's expected landfall in Central America is likely to be a major disaster. Although a small storm, Beta will bring 10-20 inches of rain over the interior mountainous regions of Nicaragua and Honduras, creating a serious flooding situation. The GFDL model indicates that Beta will survive the crossing of Nicaragua and emerge into the Pacific Ocean, where it will re-intensify into a Category 1 hurricane. The projected path takes the storm northwest along the coast of El Salvador, potentially adding to the destruction caused by Hurricane Stan earlier this month, which killed 69. Beta may also continue on to affect Guatemala, which suffered the cruelest blow of any nation this destructive hurricane season; between 1500 and 2000 Guatemalans died in floods and mudslides spawned by Hurricane Stan. The threat to El Salvador and Guatemala remains highly speculative at this point, since we are talking about events a week or more in the future.

There are no provisions for what to do in the event we have to retire Beta's name and replace it on the list of hurricane names. One possibility is that the storm will be dubbed Beta-2005 and the name Beta will be reused. Another possibilty is that Beta will be skipped over next time the Greek alphabet comes into use.


Figure 1. Current sea surface temperatures show the warmest waters in the North Atlantic are in the region just north of Panama where Beta formed.

Elsewhere in the tropics
The strong tropical wave spreading heavy rains through the Lesser Antilles remains disorganized today. The amount of deep convection has increased some since yesterday, but remains spread out along a long line. A weak circulation center has developed along the south edge of this line, near 12N 60W (the island of Barbados). Wind shear over the wave has decreased to 5 - 10 knots today, and is forecast to decrease further the next few days as the wave pushes into the central Caribbean. Development of a new tropical depression could occur as early as Saturday with this system. Any storm developing from this wave would likely be a threat to Nicaragua, Honduras, Belize, or Mexico later next week.

Another tropical wave, midway between Africa and the Lesser Antilles, remains poorly organized as it moves westward at 15 mph. While a circulation center has developed near 9N 40W, upper level winds are currently unfavorable for development of this system.

Jeff Masters

TD 26 forming?

By: JeffMasters, 7:44 PM GMT on October 26, 2005

The tropical disturbance in the extreme south central Caribbean north of Panama appears to have spun up into a tropical depression this afternoon. A strong circulation has developed near 10.2N 81W, and some solid deep convection has built up on the northwest side of the circulation, near the coast of Nicaragua. Radar out of Panama can only see the east side of the storm, and echoes on this side are very weak. The system has a long ways to go before reaching tropical storm strength.

The computer models, as usual for a developing system, are all over the place. The general consensus is for a slow northwesterly track with a landfall in eastern Nicaragua on Friday. The latest 8am EDT runs of the GFDL and NOGAPS model don't develop the system at all. This is quite a contrast to last night's 8pm EDT run of the GFDL model, which forecasted a Category 2 hurricane hitting Nicaragua Friday. A more plausible solution is the SHIPS intensity model, which brings the system up to a 50-mph tropical storm before landfall on Friday. The wind shear is light--less than 10 knots now--and water temperatures are warm (85 F, 30C), so we should see Tropical Storm Beta here by Thursday night. This system could bring heavy rains of 5 - 10 inches to Nicaragua this weekend, causing life-threatening flash floods and mudslides. Costa Rica and Honduras could also see significant rains from this system.


Figure 1. Early model tracks for developing disturbance north of Panama.

Elsewhere in the tropics
The strong tropical wave approaching the Leeward Islands remains disorganized today. The wave will spread heavy rains to those islands tonight and to Puerto Rico on Thursday. Wind shear levels are about 10 - 15 knots, which is marginal for tropical storm development. There are no signs of a surface circulation at this time. This system looks similar to the tropical wave that spawned Tropical Storm Alpha, so we'll have to watch it as it moves into the Caribbean.

Jeff Masters

Wilma is gone

By: JeffMasters, 1:04 PM GMT on October 26, 2005

Wilma and New England
Wilma is gone. Cold waters and strong winds weakened her to a remnant low pressure system last night, which is now far out over the open Atlantic. Wilma claimed one last victim yesterday in Massachusetts, an unwary body surfer who never returned to shore. In Massachusetts, Wilma and a Nor'easter that developed next to the coast brought winds and rain that knocked out power to 70,000 residents. Winds gusted as high as 66 mph in Massachusetts, and 20-foot high waves and a two foot storm surge caused minor coastal flooding.

Wilma and Florida
You can tell electricity is beginning to return to many of the six million people who lost power during Wilma's rampage over Florida Monday--the number of wunderphotos posted of the damage has increased markedly, and I have made links to some of the more dramatic ones below. I had planned today to discuss in more detail the asymmetries of Wilma's winds on the hurricane's right and left sides as it moved so quickly over Florida, but the images I wanted to use are on a computer at NOAA's Hurricane Research Division, which is on Virginia Key in Miami. Most of Miami is still without power, and this discussion will have to wait until power is restored to the lab. Those of you trying to access the Hurricane FAQ will meet with a similar problem--the FAQ is on a computer in Miami. The National Hurricane Center, however, is still able to provide Internet access to its products.

Damage estimates for Wilma's insured damage now range from $6 - $9 billion in Florida, making it the third most costly hurricane in U.S. history. When combined with the damage done to Mexico and other Caribbean nations, Wilma may turn out to be the second costliest Atlantic hurricane of all time.

Tropical disturbance north of Panama
A tropical disturbance in the extreme south central Caribbean north of Panama has gotten better organized this morning. Two surface circulations have developed, one near 10N 81W just off the northwest coast of Panama, and one at 11N 76W just off the northwest coast of Venezuela. An impressive blow-up of deep convection is occurring this morning, and the QuikSCAT satellite measured winds of 15 - 25 mph, and one wind vector of 50 mph. Wind shear values over the disturbance have dropped to 10 knots, and are forecast to remain low this week. Most of the global forecast models predict that a tropical depression will form in this region later this week, and move slowly west-northwest toward Nicaragua.

Elsewhere in the tropics
A strong tropical wave is approaching the Leeward Islands today, and will spread heavy rains to those islands today and to Puerto Rico Thursday. Wind shear levels are about 10 - 15 knots, which is marginal for tropical storm development. There are no signs of a surface circulation at this time. This system looks similar to the tropical wave that spawned Tropical Storm Alpha, so we'll have to watch it as it moves west-northwest at 15 mph.

I'll be back later this afternoon with an update if either of these systems develop.

Jeff Masters

Wilma drenches New England

By: JeffMasters, 2:11 PM GMT on October 25, 2005

Wilma continues racing northeast at 55 mph towards Canada, and is still maintaining Category 2 winds of 100 mph. Wind shear of 50 knots is beginning to take its toll, though, and the top potion of the storm is being ripped away from the surface portion, resulting in steady weakening. By tonight, Wilma will pass north of the warm Gulf Stream waters into waters of just 20 C, resulting in rapid weakening to a tropical storm and then to a regular extratropical cyclone. The forward speed of 55 mph means that the winds on the east side of the storm are blowing at 100 mph, and the winds on the west side just 45 mph--quite an asymmetry!

Wilma and New England
Today and tonight, Wilma will dramatically affect New England's weather. A separate powerful Nor'easter storm is developing next to the coast of New England, and moisture feeding back from Wilma into the Nor'easter will drench much of Rhode Island, southeast Massachusetts, and surrounding areas with 2 - 4 inches of rain. In the northern portions of Maine and New Hampshire, the precipitation will come as snow, and reach 6 - 8 inches depth. Snowfall amounts in the Adirondacks will exceed 12 inches, and heavy snow of six inches has already been reported in the Laurel Highlands east of Pittsburgh.

Winds from the combined Nor'easter/Wilma storm will reach sustained levels of 40 - 50 mph over the waters near Cape Cod, and bring wind gusts of 50 mph to New York City, Providence, and Boston. A storm surge of 3.5 feet with 26 foot waves is expected to cause moderate flooding along the coast of southeast Massachusetts, similar to what was experienced with the blizzard of December 2003. Wilma and the Nor'easter will merge on Wednesday, bringing Nova Scotia and Newfoundland tropical storm force winds, heavy rain, and coastal flooding. New England residents, take heart: the
second Nor'easter the computer models were predicting for Sunday now appears to be a non-threat. Yes, the same computer models that have trouble with long range hurricane forecasts also do poorly on winter storms sometimes!

Were the winds on Wilma's backside stronger?
I heard numerous reporters and eyewitnesses say that that after Wilma's eye passed, the winds on the back side were much stronger. A check of the wind history at Fort Lauderdale shows that this was the case there. Sustained winds peaked at 66 mph before the eye's passage, and were 69 mph after. However, most other wind traces I have examined show the opposite trend. For example, West Palm Beach reported peak sustatined winds of 82 mph before eye passage, and 76 mph after. In general, this is what we would expect, since the storm weakened as it passed over Florida. However, there were enough asymmetries caused by friction and interaction with land that some intense thunderstorms wrapped around to the back side of Wilma causing stronger winds there for some areas. In many cases, the perception that stronger winds occurred on the backside was incorrect. After a long lull, the sudden onset of hurricane force winds makes the winds seem stronger, compared to the slow build up of winds that occurs when the storm is first approaching.

Are we done with hurricane season yet?
No. Hurricane season runs through the end of November. On average, we get one tropical storm every other year between now and the end of the year. Given that this is no ordinary year, I think we can expect at least one more tropical storm. However, I do think that the hurricane season for the United States is over. An strong cold front behind Wilma has spread unseasonably cool air across the Gulf of Mexico, the Bahamas, Cuba, and into the northwest Caribbean. This cool air will significantly chill the ocean waters surrounding the U.S., making it difficult for a tropical storm to form or maintain its strength near the U.S.

Tropical disturbance north of Panama
While hurricane season may be over for the U.S., it is definitely not over for the Caribbean. A tropical disturbance in the extreme south central Caribbean north of Panama bears watching this week. Currently, the cloud pattern is disorganized, and wind shear values of 20 knots are too high to allow development. However, wind shear values are expected to drop the next few days, possibly allowing some tropical development to occur later in the week. Most of the global forecast models predict that a tropical depression will form in this region later this week. Any development in this region would be a threat to Costa Rica, Nicaragua, northeast Honduras, and the islands to their north.

Jeff Masters

Wilma strengthens, heads out to sea

By: JeffMasters, 10:01 PM GMT on October 24, 2005

Wilma continues to confound forecasters, and has intensified once more into a Category 3 hurricane with 125 mph winds, despite wind shear levels that would normally barely support a hurricane. In fact, Wilma is close to Category 4 status--the 5 pm hurricane hunter flight found winds at 10,000 feet of 157 mph, which normally translates to a surface wind of 140 mph--Category 4 winds. Wilma is over the Gulf Stream, which has warm water temperatures of 28 C capable of supporting a major hurricane. Wilma is racing northeast at 40 mph away from Florida, but is still bringing tropical storm force wind gusts to both the east and west coasts of Florida. A wind gust of 39 mph was measured at Naples at 4 pm EDT today.

Wind reports
Here are the maximum sustained winds and gusts (in mph) measured during Wilma:

Miami: 67 gust 91 8:30am
West Palm Beach: 82 gust 100 9:10 am
Fort Lauderdale: 69 gust 96 10:53 am
Pompano Beach: 83 gust 120 mph 8:48 am
Alligator Alley, west of US 27: 85 gust 104 8:19 am
Grand Bahama: 95 gust 111 12:00 pm
Naples: 80 gust 97 8:30 am
Key Largo: 101 gust 123 8:00 am

And some peak wind gusts:
Naples EMO: 121 mph
Ochopee, Collier County: 105 mph
Everglades City: 97 mph
Opa Locka: 105 mph
Everglades National Park: 112 mph
Doral: 111 mph
National Hurricane Center: 104 mph
Boynton Beach: 103 mph

North Carolina
Wilma will race northeastward off the coast, but spare North Carolina her fury. Only 20 - 30 mph winds are expected on the Outer Banks tonight, and the moderate rain now falling across eatern North Carolina will end by 4 am Tuesday.

New England
On Tuesday, Wilma will dramatically affect New England's weather. A separate powerful Nor'easter storm will develop next to the coast of New England on Tuesday, and moisture feeding back from Wilma into the Nor'easter will drench much of Rhode Island, southeast Massachusetts, and surrounding areas with 2 - 4 inches of rain. Winds from the combined Nor'easter/Wilma storm will reach sustained levels of 40 - 50 mph over the waters near Cape Cod, and bring wind gusts of 50 mph to New York City, Providence, and Boston. A storm surge of 1 - 3 feet with 20 foot waves is expected to cause moderate flooding along the coast of southeast Massachusetts. As Wilma continues northeast on Wednesday, New Brunswick and Newfoundland will experience tropical storm force winds, heavy rain, and coastal flooding.

Wilma's impact
Downtown Clewiston, next to Lake Okeechobee, suffered extensive damage. Up to 35% of the land area of Key West suffered inundation from Wilma's storm surge. The damage to the Keys and the rest of Florida is still unclear, but preliminary estimates of the total insured plus uninsured damage are $4 - $18 billion. It is also too early to gauge Wilma's impact on Mexico. Between 30-40% of the population in Cancun has suffered some damage to their housing. Reports are not in yet from the hardest hit areas, Cozumel and Playa del Carmen, which is a bad sign. Wilma caused heavy damage in Havana, where huge waves pushed flood waters up to four blocks inland, and flooded the city up to three feet deep. Damage to Haiti, Jamaica, Honduras, and Belize was also substantial. Including the damage done to Mexico and the rest of the Caribbean, Wilma will probably be the second most costly hurricane of all time, next to Katrina.

Alpha
Alpha is no more, destroyed by big sister Wilma's strong winds. In Haiti, eight are dead from flooding and mudslides triggered by Alpha's 4 - 8 inches of rain. At least 400 homes were destroyed, and twenty-three people have been reported missing, including 19 who were swept away by floodwaters in the town of Leogane, west of the capital.
Three people are missing from floods in the neighboring Dominican Republic.

Nor'easter season
New England residents, take note: it's now Nor'easter season! A second Nor'easter is expected to significantly impact the area on Sunday, bringing high winds, heavy rain, and the threat of coastal flooding from North Carolina to Maine. I'll be back Tuesday morning to discuss the current Nor'easter and Wilma, plus the outlook for Sunday's Nor'easter. Hurricane season is close to ending; it's time to start thinking about winter storms.

Wilma heads out to sea

By: JeffMasters, 4:04 PM GMT on October 24, 2005

Wilma's eye has moved out to sea offshore the coast of Florida, but remains a dangerous Category 2 hurricane with top winds of 105 mph. Wilma will continue to generate hurricane force winds, flooding, and isolated tornadoes until late afternoon over much of southern Florida. The highest winds measured so far in association with Wilma were at Fowey Rocks on Key Largo south of Miami. That station measured sustained winds of 101 mph, gusting to 123 mph, at 8 am EDT.

Despite being subjected to 30 knots of wind shear on her southwest side last night, Wilma was large enough to be able to intensify in spite of the shear. She smashed ashore near Marco, Florida at 6:30 am EDT this morning as a Category 3 hurricane with sustained winds of 125 mph. Wilma raced across southern Florida at 25 mph, crossing the state in just four hours. The large 65 mile diameter eye brought up to an hour of calm to locations along its path, and passed directly over West Palm Beach. Winds there never fell below 23 mph, though, so the "calm" was only relative. Sustained winds at the West Palm Beach airport reached 82 mph, with gusts to 101 mph, at 9:10 am. The automated weather station reported snow at this time, but this was not really the case!

Wind reports
Here are the maximum sustained winds and gusts (in mph) measured so far in the storm. Wilma is slowly weakening due to wind shear and cooler waters, so we have probably seen her highest winds:

Miami: 67 gust 91 8:30am
West Palm Beach: 82 gust 100 9:10 am
Fort Lauderdale: 69 gust 96 10:53 am
Pompano Beach: 83 gust 120 mph 8:48 am
Alligator Alley, west of US 27: 85 gust 104 8:19 am
Grand Bahama: 95 gust 111 12:00 pm
Naples: 80 gust 97 8:30 am
Key Largo: 101 gust 123 8:00 am

A tornado was reported near Cape Canaveral this morning, and several tornado signatures have been detected on radar. The threat of tornadoes is quite high for this hurricane, due to the presence of a cold front on the north side.


Figure 1.Storm total rainfall from the Tampa radar. Rainfalls amounts of up to 10 inches have been measured, mostly to the north of the Wilma's track.

Where will Wilma go?
Wilma will race northeastward off the coast, bringing winds of 35 - 45 mph to North Carolina's Outer Banks today, and 2 - 4 inches of rain. Already, one to two inches of rain has fallen over much of eastern North Carolina. On Tuesday, Wilma will transition to a powerful 'Noreaster storm for New England, bringing sustained winds of 40 - 50 mph over the waters near Cape Cod. A storm surge of 1 - 3 feet with 20 foot waves is expected to cause minor flooding along the coast of Massachusetts. As Wilma continues northeast on Wednesday, New Brunswick and Newfoundland will experience tropical storm force winds, heavy rain, and coastal flooding.

Wilma's impact
The airport and the runway at Key West's Naval Air Station are under water and up to 35% of the land area of Key West suffered inundation from Wilma's storm surge. The damage to the Keys and the rest of Florida is still unclear, but undoubtedly is tens of billions of dollars. It is also still to early to gauge Wilma's impact on Mexico. Reports are not in yet from the hardest hit areas, Cozumel and Playa del Carmen, which is a bad sign. Wilma caused heavy damage in Havana, where huge waves pushed flood waters up to four blocks inland, and flooded the city up to three feet deep. Damage to Haiti, Jamaica, Honduras, and Belize was also substantial. I'll have more detailed damage statistics when they become available. Including the damage done to Mexico, Wilma will probably be the second most costly hurricane of all time, next to Katrina.

Alpha
Tropical Depression Alpha survived its encounter with Hispanolia, and brought 30 mph winds and 1 - 2 inches of rain to the Turks and Caicos Islands last night and this morning. Strong winds blowing over Alpha from the circulation of Hurricane Wilma will destroy Alpha later today. At least five people were killed in Haiti due to flash floods triggered by Alpha, and this total is likely to go higher. However, Alpha only dropped about 4 - 8 inches of rain over Haiti--not enough to trigger a massive flooding disaster like occurred during Hurricane Jeanne last year.

I'll post an update late this afternoon. Special thanks go to the National Hurricane Center and the local Florida National Weather Service offices, whose reports I rely on very heavily for my blog posts! They are working very hard through this storm while their families and homes are being threatened.

Jeff Masters

Wilma smashes ashore near Marco Island

By: JeffMasters, 11:37 AM GMT on October 24, 2005

Wilma smashed ashore near Marco, Florida at 6:30 am EDT this morning as a Category 3 hurricane with sustained winds of 125 mph. The Hurricane Season of 2005 continues to rewrite the rules, as Wilma maintained an impressive intensification phase right up until landfall in the face of very significant wind shear--up to 30 knots. Current Miami radar shows that the southwest side of Wilma is being strongly affected by this wind shear--the echoes are much less intense on that side.


Figure 1. Latest Miami radar shows strong convection on the east side of Wilma, but weak echoes on the southwest side where wind shear is affecting the storm.

Wilma's forward speed is 23 mph, up from 20 mph just one hour ago. Due to the fast forward speed, this will be a short but very intense hurricane event for South Florida. Hurricane force winds extend out about 80 miles from Wilma's center, so the longest duration of hurricane-force winds will occur on the coast at Marco, where about five hours of hurricane force winds will occur. Hurricane force winds will begin by 10 am near West Palm Beach and Fort Lauderdale, and continue for about four hours. Intereaction with land and high wind shear will weaken Wilma as she crosses Florida, but Wilma is expected to be a Category 2 hurricane as she crosses the east coast of Florida. Sustained winds of 95 mph with gusts to 120 mph are possible along the east coast of Florida near and to the south of the eye, primarily before the eye crosses the coast. Winds should be a full 20 mph weaker when the back side of the hurricane hits, as wind shear is substantially affecting the storm's rear portion. A period of calm of up to an hour can be expected along the center of Wilma's track. If you must go outside during that period, realize that the winds can go from calm to 100 mph in just one minute when the back side of the hurricane moves over you. If you are near the edge of the eye, the calm period may last only a few minutes, so do not venture far from safety if you must go outside.

Wind reports
Reports are no longer available from Key West International Airport due to communications outage. Winds there were 60 mph gusting to 76 mph before the failure. Recent peak wind gust reports from other gauges include 120 mph at 453 am on Cudjoe Key, 101 mph at Sombrero Key at 449 am, and 74 mph at Long Key at 455 am. By 10 am EDT hurricane force winds should end in the Keys.

The wind at Naples at 553 am was north at 56 mph gusting to 75 mph, Miami had 60 mph gusting to 74 mph at 7:34 am, Fort Lauderdale had 51 mph gusting to 73 mph at 7:16 am, and West Palm Beach had winds of 43 mph gusting to 54 at 6:53 am. Several tornados signatures have been detected on radar, and the threat of tornadoes is quite high for this hurricane, due to the presence of a cold front on the north side of the hurricane.

Storm Surge
A storm tide of up to 13 to 18 feet is now occurring on the mainland, south of Naples. Fortunately, this area is mostly uninhabited Evergaldes swamp. The surge is causing extensive flooding of local access roads to Marco Island, Everglades City, and Chokoloskee including state roads 92, 951, 953 and 29 and large parts of the Tamiami Trail U.S. Highway 41. Everglades City is likely flooded or will be shortly, and parts of Chokoloskee and Marco Island are also likely flooded. Further north along the Collier County coast, a storm tide of 7 to 9 feet is occurring from north of Marco Island to South Naples. Since the wind flow is offshore at Naples much lower storm tides are occurring from Naples north to Bonita Beach. Fort Myers has dodged a major bullet, and will be spared significant storm surge damage, and will receive only moderate wind damage at Category 1 hurricane levels.

A storm tide of 8 to 13 feet above mean sea level is now occurring on Cape Sable and in Flamingo. Much of Flamingo is now likely flooded. Along the Atlantic coast of Miami-Dade County, particularly Biscayne Bay, tides are running 2 to 3 feet above normal. A storm tide of 3 to 5 feet above mean sea level can be expected around 8 to 9 am EDT, with slightly higher amounts possible in canals and waterways. South winds will pile some water into the north end of Biscayne Bay causing some flooding of causeways and low lying beach access roads for a short time from early to mid morning Monday. Some flooding from surge will occur in low lying areas of Matheson Hammock and Fairchild Tropical Gardens and parts of Coral Gables and Coconut Grove and along the mouth of the Miami River. Flooding of low lying areas on the Bay sides of Key Biscayne and Virginia Key can also be expected. Over the Broward and Palm Beach County coasts, storm tides of 2 to 3 feet can be expected mid morning.

For Lake Okeechobee, a storm surge of 5 to 7 feet above Current Lake levels is expected from early morning to around noon Monday over areas inside the dike from Lakeport to Clewiston, with 2 to 5 feet above current lake levels
elsewhere from Buckhead Ridge south to Lakeport, and from Clewiston through Port Mayaca. This will cause some flooding of low areas outside Hoover Dike protection including Torry, Kreamer, and Ritta islands and some access roads.

I'll post an update later this morning. Special thanks go to the National Hurricane Center and the local Florida National Weather Service offices, whose reports I rely on very heavily for my blog posts! They are working very hard through this storm while their families and homes are being threatened.

Jeff Masters

Wilma steadily intensifying

By: JeffMasters, 9:27 PM GMT on October 23, 2005

Wilma has entered a slow intensification phase the past three hours. The pressure has fallen from 963 mb to 959 mb, the eye has shrunk in diameter from 60 nm to 45 nm, and satellite imagery shows cooling cloud tops in the eyewall region--all signs of an ongoing intensification cycle. In response to this intensification cycle, the Hurricane Center has now upped their forecast of the maximum storm surge from 13 feet to 17 feet over southwest Florida. At the current rate of intensification, Wilma could become a Category 3 hurricane with 115 mph winds by midnight.

This intensification phase should slow down or reverse by midnight, since shear is now increasing over the storm. Shear is now about 15 knots, up from 10 knots this morning. The hurricane hunters noted that strong westerly winds aloft have pushed the top of the storm eastward, so that the area of calm in the eye at 10,000 feet is about ten miles east of the surface calm area. This stretching is also beginning to be evident on satellite images, with the shape of the hurricane appearing less circular. Assuming that the shear begins weakening the hurricane at midnight, only six or eight hours remain for the shear to weaken the hurricane before landfall at 6 am or 8 am Monday morning. This may not be enough time to weaken the storm much, so I am still anticipating a 105 mph Category 2 hurricane at landfall. By the time Wilma crosses the Florida Peninsula and arrives at the east coast of Florida, she should have top winds of about 85 mph.

The remainder of my discussion from noon today appears below, unchanged.

Assuming my forecast of a landfall near Marco, Florida as a Category 2 hurricane with 105 mph winds is a good one, we can expect a storm surge of 8 to 14 feet near that city and to the south. The Keys would see storm surge flooding of 5 to 8 feet. Fortunately, the area south of Marco is primarily uninhabited--the Everglades swamp. However, if Wilma comes ashore north of Naples--or further south near the Keys--storm surge flood damage in those areas could easily reach billions of dollars. Storm surge flooding should be only 2 - 4 feet on the east coast of Florida, where wind damage is the primary threat.


Figure 1. Storm surge map for southwest Florida.

Wilma's winds and rain
Wilma will be moving too fast to dump more than 5 - 10 inches of rain. The rain will be concentrated on the north side of the hurricane, since there will be a cold front there that will trigger more condensation. Areas to the north of the eye's passage will see winds a full Category--25 to 30 mph--lower than those on the south. This is because the storm's high rate of forward motion, near 25 - 30 mph, will add to the windspeeds seen on the south side of the Wilma's counterclockwise rotation, and subtract on the north side. Since the storm will be moving so fast, the duration of hurricane force winds will be just a few hours.

After Florida, then what?
After crossing Florida, Wilma should bring 50 - 60 mph winds to the northern Bahama Islands, but not hurricane force winds. Wilma should pass close enough to North Carolina's Outer Banks to bring 40 mph winds there and up to an inch of rain. It now appears that Wilma will bring 40 mph winds and 1 - 3 inches of rain to southeast Massachusetts, along with 20 foot waves. Boston, which has already had its fourth wettest October ever with 7.52 inches of rain, may break its October record. Nova Scotia will probably bear the brunt of Wilma's fury, receiving a direct hit by the center, along with 45 - 55 mph winds and rains of 3 - 5 inches.

Alpha
Tropical Storm Alpha, the record-breaking 22nd tropical storm of this unbelievable hurricane season, has come ashore over Haiti and the Dominican Republic. Heavy rains of up to 12 inches could cause heavy loss of life in Haiti, where 98% deforestation rates have left the island highly vulnerable to flooding from even ordinary fast-moving tropical storms like Alpha. In the event a major flood disaster does ensue, dictating the retirement of Alpha's name, there are no contingency plans on how to replace Alpha's name on the list. Alpha is moving fast enough that I am hopeful a major flooding disaster will be averted in Haiti, though.

The 10,000 foot high mountains of Hispanolia have seriously disrupted the circulation of Alpha, making it questionable how much will remain of the storm to threaten the Turks and Caicos Islands. In any event, Alpha does not have long to live, as the huge circulation of Hurricane Wilma will overtake it by Tuesday and destroy the storm with high wind shear.

I'll be back with an update in the morning, or later tonight if events warrant.

Jeff Masters

Wilma no stronger yet

By: JeffMasters, 4:03 PM GMT on October 23, 2005

Wilma is ending its long pounding of Mexico's Yucatan, and is now steadily accelerating towards its next target--southern Florida. The eye has been offshore the Yucatan for about 12 hours now, but no intensification has occurred--yet. The latest hurricane hunter flight, at 11 am EDT, found a central pressure of 964 mb, up 3 mb from the previous flight at 7 am EDT. Wilma has a very large 70 mile diameter eye, thanks to the collapse of the inner eyewall during passage over the Yucatan.

Data from satellites, Cancun radar, and the hurricane hunters all show that the inner eyewall is now re-establishing itself over the warm waters of the Gulf of Mexico. This inner eyewall has a diameter of about 12 miles, and if it has time to fully form, could generate Category 3 hurricane winds at landfall in southwest Florida. Wind shear over Wilma is currently about 10 knots--the same level we've seen for the past few days. This shear is expected to remain at this level until about midnight tonight, and allow intensification until then. Thereafter, the wind shear will steadily increase, putting an end to Wilma's intensification phase and probably weakening her just before landfall on Monday. Wilma's size and fast forward motion may not give the shear much chance to weaken her significantly, and there is still about a 10% chance that Wilma could hit Floridsa as a Category 3 hurricane. However, given the limited time Wilma has to re-establish her inner eyewall, and the significant shear expected to assert itself, the most likely intensity at landfall is a Category 2. A Category 1 storm at landfall is a good possibility, as well. Ordinarily, the crossing of the Florida Peninsula should weaken a hurricane by about 10 mph, but in Wilma's case, her winds should be 15 - 20 mph weaker on the east coast of Florida, due to the extra time significant wind shear will have to weaken her.

Assuming my forecast of a landfall near Marco, Florida as a Category 2 hurricane with 105 mph winds is a good one, we can expect a storm surge of 8 to 14 feet near that city and to the south. The Keys would see storm surge flooding of 5 to 8 feet. Fortunately, the area south of Marco is primarily uninhabited--the Everglades swamp. However, if Wilma comes ashore north of Naples--or further south near the Keys--storm surge flood damage in those areas could easily reach billions of dollars. Storm surge flooding should be only 2 - 4 feet on the east coast of Florida, where wind damage is the primary threat.


Figure 1. Storm surge map for southwest Florida.

Wilma's winds and rain
Wilma will be moving too fast to dump more than 5 - 10 inches of rain. The rain will be concentrated on the north side of the hurricane, since there will be a cold front there that will trigger more condensation. Areas to the north of the eye's passage will see winds a full Category--25 to 30 mph--lower than those on the south. This is because the storm's high rate of forward motion, near 25 - 30 mph, will add to the windspeeds seen on the south side of the Wilma's counterclockwise rotation, and subtract on the north side. Since the storm will be moving so fast, the duration of hurricane force winds will be just a few hours.

After Florida, then what?
After crossing Florida, Wilma should bring 50 - 60 mph winds to the northern Bahama Islands, but not hurricane force winds. Wilma should pass close enough to North Carolina's Outer Banks to bring 40 mph winds there and up to an inch of rain. It now appears that Wilma will bring 40 mph winds and 1 - 3 inches of rain to southeast Massachusetts, along with 20 foot waves. Boston, which has already had its fourth wettest October ever with 7.52 inches of rain, may break its October record. Nova Scotia will probably bear the brunt of Wilma's fury, receiving a direct hit by the center, along with 45 - 55 mph winds and rains of 3 - 5 inches.

Alpha
Tropical Storm Alpha, the record-breaking 22nd tropical storm of this unbelievable hurricane season, has come ashore over Haiti and the Dominican Republic. Heavy rains of up to 12 inches could cause heavy loss of life in Haiti, where 98% deforestation rates have left the island highly vulnerable to flooding from even ordinary fast-moving tropical storms like Alpha. In the event a major flood disaster does ensue, dictating the retirement of Alpha's name, there are no contingency plans on how to replace Alpha's name on the list. Alpha is moving fast enough that I am hopeful a major flooding disaster will be averted in Haiti, though.

The 10,000 foot high mountains of Hispanolia have seriously disrupted the circulation of Alpha, making it questionable how much will remain of the storm to threaten the Turks and Caicos Islands. In any event, Alpha does not have long to live, as the huge circulation of Hurricane Wilma will overtake it by Tuesday and destroy the storm with high wind shear.

I'll be watching Wilma this afternoon, and will have a new report by 5 pm.

Jeff Masters

Alpha sets all-time record

By: JeffMasters, 10:43 PM GMT on October 22, 2005

Ever since the formation of two major hurricanes in July made it clear that the Hurricane Season of 2005 was going to challenge 1933 as the busiest season ever, I've been expecting to see the words "Tropical Storm Alpha" emblazoned on a hurricane tracking chart. Well, we've got the record now. The formation of Tropical Storm Alpha, the 22nd storm of the season, now makes 2005 the busiest hurricane season of all time. Still, it looks really strange to see the words "Tropical Storm Alpha" on the hurricane tracking charts, and gives a surreal cast to Hurricane Season of 2005 as we approach the Halloween season.

In keeping with the season, we have two very scary storms to talk about. The eye of very dangerous Category 2 Hurricane Wilma is moving offshore the Yucatan mainland this evening, a little earlier than I expected. This makes it more likely Wilma will be a bit stronger at landfall in Florida Monday--perhaps a strong Category 2 with 105 mph winds. We are not good at making intensity forecasts, and Wilma could easily be a Category stronger--or weaker. The argument for a weaker hurricane goes like this: Wilma's inner eyewall has collapsed, leaving an outer eyewall with diameter 80 miles in place. When an inner eyewall collapses like that, it usually takes at least a day for the eyewall to reform, and by a day from now, Wilma will start experiencing increased wind shear which will weaken her down to a Category 1.

The argument for a stronger hurricane goes like this: Wilma still has a large, intact circulation, and is still a Category 2 hurricane. She will not follow the usual normals (since this is the Hurricane Season of 2005, after all), and will re-intensify quickly over the warm waters that nurtured her rise to Category 5 status this week. By late Sunday, she will be a Category 3 hurricane again, and large enough and fast moving enough that the shear affecting her will be unable to significantly weaken her. Wilma will make landfall as a major hurricane on Florida's west coast.

So, both scenarios are plausible, and Florida must be prepared for the arrival of a major hurricane on Monday. Landfall anywhere between Sarasota and the Keys is possible.

The remainder of my 1 pm post appears below, mostly unchanged.

The most extreme winds of the eyewall have now been battering Cozumel and the mainland Yucatan Peninsula for over 30 hours. Sustained winds of 100 - 140 mph affecting a built-up resort area like Cozumel/Cancun for so long must have done extreme damage. Wilma has weakened to a Category 2 hurricane with 100 mph winds. Still, the damage to Mexico will increase today as structures already weakened by 30 hours of relentless winds continue to receive another 12 hours of stress.

Conditions in Cancun
Wunderblogger LizinCancun reported yesterday on conditions in Cancun:

"We evacuated our home in Cancun yesterday and came 200 miles west to Merida. Our home sits about 100 feet away from the beach. The waves were crashing over our 6 foot tall sea wall yesterday before we left and destroyed the palapa that sits about 10 feet out in the water. We fully expect our home and all our belongings to be gone. We lost contact with all of our friends that stayed, cell and land lines are down of course as is power. We just talked with a friend that says the power is out, phones only working when the generators are running to pump out all the water. He said the hotel is blowing apart (not in the hotel zone) and all you can see when looking outside is a wall of water blowing sideways and pieces of things being shredded by the high winds, some huge."


Figure 1. Total rainfall for the week. Image generated by NASA's TRMM rainfall measuring satellite.

A deluge of rain
Rainfall amounts in Mexico from Wilma have been extreme. Isla Mujeres, just offshore from Cancun, has reported almost 35" of rain over the past 1 1/2 days, and at one point reported 4" of rain in one hour between 2 and 3 am EDT today. Rainfall amounts in Cuba have not been nearly so extreme--at least in the areas of western Cuba that are still reporting data. San Juan y Martinez measured 10.7 cm (4.2 inches) of rain the past 24 hours, and storm total rainfall amounts of up to 18 cm (7 inches) have been measured in Cuba's westernmost province. Grand Cayman received five inches, Jamaica's Kingston airport eight inches, and Belize four inches. The north coast of Honduras has had numerous locations receive ten inches of rain, with one unofficial report of 20 inches. Rainfall in Haiti reached 8 - 10 inches, and, triggered flash floods that killed 11 people.

How will Wilma affect Florida?
The latest 8 am EDT (12Z) model runs are in, and continue to agree on the basic scenario that Wilma will move offshore the Yucatan tonight as a weak Category 2 hurricane. On Sunday, the storm will move slowly north and then northeast as westerly winds from a strong trough of low pressure start affecting the storm. There is about an 18-hour window of opportunity for Wilma to re-intensify to a Category 3 hurricane on Sunday. By Sunday night, the Wilma will begin to accelerate, and wind shear will begin to weaken the storm. By Monday morning, Wilma will cross the west coast of Florida between Fort Myers and the Keys as a Category 1, 2, or 3 hurricane. My best guess is that Wilma will be a 110-mph Category 2 hurricane hitting near Marco. Storm surges tend to be worse with large and faster moving hurricanes, so I would expect a storm surge characteristic of a Category 3 hurricane, 10 to 16 feet, in and south of Marco, causing very heavy damage in that city. Fortunately, the area south of Marco is primarily uninhabited--the Everglades swamp. However, if Wilma comes ashore north of Naples--or further south near the Keys--storm surge flood damage in those areas could easily reach billions of dollars. Storm surge flooding should be only 2 - 4 feet on the east coast of Florida, where wind damage is the primary threat.


Figure 2. Storm surge map for southwest Florida.

Wilma's winds and rain
Wilma will be moving too fast to dump more than 5 - 10 inches of rain. The rain will be concentrated on the north side of the hurricane, since there will be a cold front there that will trigger more condensation. Areas to the north of the eye's passage will see winds a full Category--25 to 30 mph--lower than those on the south. This is because the storm's high rate of forward motion, near 25 - 30 mph, will add to the windspeeds seen on the south side of the Wilma's counterclockwise rotation, and subtract on the north side. Since the storm will be moving so fast, the duration of hurricane force winds will be just a few hours.

After Florida, then what?
After crossing Florida, Wilma should bring tropical storm force winds to the northern Bahama Islands, but not hurricane force winds. Wilma should pass close enough to North Carolina's Outer Banks to bring 40 mph winds there. Wilma is not expected to bring high winds to New England, but could bring 50 mph winds to Nova Scotia five days from now.

Alpha
Alpha has formed 200 miles southeast of Hispanolia. Long range radar from San Juan, Puerto Rico shows some increasing spiral banding and echo intensity, and satellite imagery shows a good outflow channel developing to the southeast. Wind shear of about 10 knots is eroding the northwest portion of the storm.

Given the storm's expected track over Haiti, the 8 - 12 inches of rain expected may cause heavy loss of life in that country due to the inability of the deforested hillsides to handle flood waters. The Dominican Republic, which still has 70% of its forest cover, should fare relatively well.

I'll be back in the morning with the latest.

Jeff Masters

Wilma devastating Cancun; TD 25 a major threat to Haiti

By: JeffMasters, 4:19 PM GMT on October 22, 2005

The eye of very dangerous Category 2 Hurricane Wilma remains onshore the Yucatan mainland near Cancun. The most extreme winds of the eyewall have now been battering Cozumel and the mainland Yucatan Peninsula for over 24 hours. Sustained winds of 100 - 140 mph affecting a built-up resort area like Cozumel/Cancun for so long must have done extreme damage. Wilma has weakened to a Category 2 hurricane with 110 mph winds, and may further weaken to a Category 1 hurricane with 90 mph winds today as its center remains over land. Still, the damage to Mexico may double today as structures already weakened by 24 hours of relentless winds continue to receive another 12 hours of stress, and as new areas along the north coast of the Yucatan receive the eyewall's worst pounding.

Cancun radar, which is miraculously still functioning, shows the the eyewall of Wilma is degrading and starting to have gaps. The eye is now filled with clouds, and the cloud top temperatures of her eyewall clouds continue to warm as Wilma steadily weakens. When Wilma finally moves back over the ocean late tonight, she will probably be a weak Category 2 hurricane with 95 mph winds.

Conditions in Cancun
Wunderblogger LizinCancun reported yesterday on conditions in Cancun:

"We evacuated our home in Cancun yesterday and came 200 miles west to Merida. Our home sits about 100 feet away from the beach. The waves were crashing over our 6 foot tall sea wall yesterday before we left and destroyed the palapa that sits about 10 feet out in the water. We fully expect our home and all our belongings to be gone. We lost contact with all of our friends that stayed, cell and land lines are down of course as is power. We just talked with a friend that says the power is out, phones only working when the generators are running to pump out all the water. He said the hotel is blowing apart (not in the hotel zone) and all you can see when looking outside is a wall of water blowing sideways and pieces of things being shredded by the high winds, some huge."


Figure 1. Total rainfall for the week. Image generated by NASA's TRMM rainfall measuring satellite.

A deluge of rain
Rainfall amounts in Mexico from Wilma have been extreme. Isla Mujeres, just offshore from Cancun, has reported almost 35" of rain over the past 1 1/2 days, and at one point reported 4" of rain in one hour between 2 and 3 am EDT today. Rainfall amounts in Cuba have not been nearly so extreme--at least in the areas of western Cuba that are still reporting data. San Juan y Martinez measured 10.7 cm (4.2 inches) of rain the past 24 hours, and storm total rainfall amounts of up to 18 cm (7 inches) have been measured in Cuba's westernmost province. Grand Cayman received five inches, Jamaica's Kingston airport eight inches, and Belize four inches. The north coast of Honduras has had numerous locations receive ten inches of rain, with one unofficial report of 20 inches. Rainfall in Haiti reached 8 - 10 inches, and, triggered flash floods that killed 11 people.

How will Wilma affect Florida?
The latest 2 am EDT (06Z) model runs are in, and continue to agree on the basic scenario that Wilma will move offshore the Yucatan late tonight as a weak Category 2 hurricane. On Sunday, the storm will move slowly north and then northeast as westerly winds from a strong trough of low pressure start affecting the storm. There is about an 18-hour window of opportunity for Wilma to re-intensify to a Category 3 hurricane on Sunday. By Sunday night, Wilma will begin to accelerate, and wind shear will begin to substantially weaken the storm. By Monday morning, Wilma will cross the west coast of Florida between Fort Myers and the Keys as a Category 1 or 2 hurricane. My best guess is that Wilma will be a 100-mph Category 2 hurricane hitting near Marco. Storm surges tend to be worse with large and faster moving hurricanes, so I would expect a storm surge characteristic of a Category 3 hurricane, 10 to 16 feet, in and south of Marco, causing very heavy damage in that city. Fortunately, the area south of Marco is primarily uninhabited--the Everglades swamp. However, if Wilma comes ashore north of Naples--or further south near the Keys--storm surge flood damage in those areas could easily reach billions of dollars. Storm surge flooding should be only 2 - 4 feet on the east coast of Florida, where wind damage is the primary threat.


Figure 2. Storm surge map for southwest Florida.

Wilma's winds and rain
Wilma will be moving too fast to dump more than 5 - 10 inches of rain. The rain will be concentrated on the north side of the hurricane, since there will be a cold front there that will trigger more condensation. Areas to the north of the eye's passage will see winds a full Category--25 to 30 mph--lower than those on the south. This is because the storm's high rate of forward motion, near 25 - 30 mph, will add to the windspeeds seen on the south side of the Wilma's counterclockwise rotation, and subtract on the north side. Since the storm will be moving so fast, the duration of hurricane force winds will be just a few hours.

After Florida, then what?
After crossing Florida, Wilma should bring tropical storm force winds to the northern Bahama Islands, but not hurricane force winds. Wilma should pass close enough to North Carolina's Outer Banks to bring 40 mph winds there. Wilma is not expected to bring high winds to New England, but could bring 50 mph winds to Nova Scotia five days from now.

TD 25
Tropical Depression 25 has formed 200 miles southwest of Puerto Rico, and looks like a good bet to develop into a tropical storm later today. Long range radar from San Juan, Puerto Rico shows some increasing spiral banding and echo intensity, and satellite imagery shows a good outflow channel developing to the southeast. Wind shear of about 10 knots is eroding the northwest portion of the storm.

Since we are all out of names this year, TD 25 will be given the name Alpha should it develop into a tropical storm. Given the storm's expected track over Haiti, the 8 - 12 inches of rain expected may cause heavy loss of life in that country due to the inability of the deforested hillsides to handle flood waters.

I'll be back in the morning with the latest, or later today, if events warrant.

Jeff Masters

Wilma still pounding Mexico; Alpha a major to threat to Haiti

By: JeffMasters, 7:57 PM GMT on October 21, 2005

The eye of very dangerous Category 3 Hurricane Wilma remains onshore the Yucatan mainland near Cancun. The most extreme winds of the eyewall have now been battering Cozumel and the mainland Yucatan Peninsula for over 24 hours. Sustained winds of 100 - 140 mph affecting a built-up resort area like Cozumel/Cancun for so long must have done extreme damage. Wilma has weakened to a Category 3 hurricane with 115 mph winds, and will further weaken to a Category 2 hurricane with 100 mph winds today as its center remains over land. Still, the damage to Mexico may double today as structures already weakened by 24 hours of relentless winds continue to receive another 12 hours of stress, and as new areas along the north coast of the Yucatan receieve the eyewall's worst pounding.

Cancun radar, which is miraculously still functioning, shows the the eyewall of Wilma is degrading and starting to show gaps. The eye is now filled with clouds, and the cloud top temperatures of her eyewall clouds continue to warm as Wilma steadily weakens. When Wilma finally moves back over the ocean late tonight, she will probably be a weak Category 2 hurricane with 95 mph winds.

Conditions in Cancun
Wunderblogger LizinCancun reported yesterday on conditions in Cancun:


"We evacuated our home in Cancun yesterday and came 200 miles west to Merida. Our home sits about 100 feet away from the beach. The waves were crashing over our 6 foot tall sea wall yesterday before we left and destroyed the palapa that sits about 10 feet out in the water. We fully expect our home and all our belongings to be gone. We lost contact with all of our friends that stayed, cell and land lines are down of course as is power. We just talked with a friend that says the power is out, phones only working when the generators are running to pump out all the water. He said the hotel is blowing apart (not in the hotel zone) and all you can see when looking outside is a wall of water blowing sideways and pieces of things being shredded by the high winds, some huge."



>b>Figure 1. Total rainfall for the week. Image generated by NASA's TRMM rainfall measuring satellite.

A deluge of rain
Rainfall amounts in Mexico from Wilma have been extreme. Isla Mujeres, just offshore from Cancun, has reported almost 35" of rain over the past 1 1/2 days, and at one point reported 4" of rain in one hour between 2 and 3 am EDT today. Rainfall amounts in Cuba have not been nearly so extreme--at least in the areas of western Cuba that are still reporting data. San Juan y Martinez measured 10.7 cm (4.2 inches) of rain the past 24 hours, and storm total rainfall amounts of up to 18 cm (7 inches) have been measured in Cuba's westernmost province. Grand Cayman received five inches, Jamaica's Kingston airport eight inches, and Belize four inches. The north coast of Honduras has had numerous locations receive ten inches of rain, with one unofficial report of 20 inches. Rainfall in Haiti reached 8 - 10 inches, and, triggered flash floods that killed 11 people.

How will Wilma affect Florida?
The latest 2 am EDT (06Z) model runs are in, and continue to agree on the basic scenario that Wilma will move offshore the Yucatan late tonight as a weak Category 2 hurricane. On Sunday, the storm will move slowly north and then northeast as westerly winds from a strong trough of low pressure start affecting the storm. There is about an 18-hour window of opportunity for Wilma to re-intensify to a Category 3 hurricane on Sunday. By Sunday night, the Wilma will begin to accelerate, and wind shear will begin to substantially weaken the storm. By Monday morning, Wilma will cross the west coast of Florida between Fort Myers and the Keys as a Category 1 or 2 hurricane. My best guess is that Wilma will be a 100-mph Category 2 hurricane hitting near Marco. Storm surges tend to be worse with large and faster moving hurricanes, so I would expect a storm surge characteristic of a Category 3 hurricane, 10 to 16 feet, in and south of Marco, causing very heavy damage in that city. Fortunately, the area south of Marco is primarily uninhabited--the Everglades swamp. However, if Wilma comes ashore north of Naples--or further south near the Keys--storm surge flood damage in those areas could easily reach billions of dollars. Storm surge flooding should be only 2 - 4 feet on the east coast of Florida, where wind damage is the primary threat.


Figure 2. Storm surge map for southwest Florida.

Wilma's winds and rain
Wilma will be moving too fast to dump more than 5 - 10 inches of rain. The rain will be concentrated on the north side of the hurricane, since there will be a cold front there that will trigger more condensation. Areas to the north of the eye's passage will see winds a full Category--25 to 30 mph--lower than those on the south. This is because the storm's high rate of forward motion, near 25 - 30 mph, will add to the windspeeds seen on the south side of the Wilma's counterclockwise rotation, and subtract on the north side. Since the storm will be moving so fast, the duration of hurricane force winds will be just a few hours.

After Florida, then what?
After crossing Florida, Wilma should bring tropical storm force winds to the northern Bahama Islands, but not hurricane force winds. Wilma should pass close enough to North Carolina's Outer Banks to bring 40 mph winds there.
Wilma is not expected to bring high winds to New England, but could bring 50 mph winds to Nova Scotia five days from now.

TD 25
Tropical Depression 25 has formed 200 miles southwest of Puerto Rico, and looks like a good bet to develop into a tropical storm later today. Long range radar from San Juan, Puerto Rico shows some increasing spiral banding and echo intensity, and satellite imagery shows a good outflow channel developing to the southeast. Wind shear of about 10 knots is eroding the northwest portion of the storm.

Since we are all out of names this year, TD 25 will be given the name Alpha should it develop into a tropical storm. Given the storm's expected track over Haiti, the 8 - 12 inches of rain expected may cause heavy loss of life in that country due to the inability of the deforested hillsides to handle flood waters.

I'll be back in the morning with the latest, or later today, if events warrant.

Jeff Masters

Wilma pounding Cozumel

By: JeffMasters, 2:21 PM GMT on October 21, 2005

Hurricane Wilma's western eyewall is battering Cozumel Island today with sustained winds of 145 mph. Cancun radar shows the west eyewall touching Cozumel, and some intense rainbands affecting Cancun and the northeast tip of the Yucatan Peninsula with rains of over one inch per hour. Wind measurements from the Cancun and Cozumels airports are not available, and we have to rely on the hurricane hunters for wind information. The latest aircraft report at 6:10 am showed no signs that the storm was weakening yet, and Wilma still has a few hours to intensify slighty before the center moves over land.

As Wilma continues north-northwest at 4 mph today, the large eye of the storm should come ashore near Cancun, bringing enormous devastation to the 50-mile wide section of coast exposed to the intense winds of the hurricane's eyewall. A long period of calm lasting up to seven hours will accompany the passage of the slow-moving eye, givng residents the only respite from the storm they are likely to get for the next two days. During these next two days, Wilma will wander erratically over or just offshore the Yucatan. This will expose structures in the hurricane zone to very long duration hurricane force winds, creating far more destruction than Category 4 Hurricane Emily did earlier this year, or Category 5 Hurricane Gilbert in 1988. Wilma may be Mexico's most expensive hurricane disaster ever. Wilma's rains will add to the misery, reaching 20 inches or more over not just the Yucatan, but the western tip of Cuba as well.


Figure 2. Computer model tracks for Hurricane Wilma.

How will Wilma affect Florida?
During the next two days, steady weakening of the storm should occur due to interaction with land. In addition, wind shear and dry air are beginning to increase over the northwest side of the storm, and should work together to steadily reduce Wilma's strength. When the trough of low pressure expected to pick up Wilma finally does sweep her east towards Florida, wind shear will be quite high and increasing, leading to continued steady weakening. The final strength of Wilma at landfall in south Florida could still range from Category 3 to tropical storm. It all depends upon how much time Wilma spends over water. If the UKMET model is right, Wilma will spend very little time over land, and arrive at Florida as a Category 3 hurricane. If the GFDL model is right, Wilma will spend more than two days over land and weaken to a tropical storm, and eventually move across Cuba as a tropical storm, missing Florida entirely.

Given all these factors, I don't see any reason to change the range of probabilities I gave yesterday for Florida. I'd give Wilma a 10% chance of arriving on the Florida west coast as a Category 3 or higher storm, 20% as a Category 2, 40% as a Category 1, and 30% as a tropical storm. On Florida's east coast, knock these value down by half a Category (10 - 15 mph).

The timing of this expected blow on Florida is still difficult to pin down. Some models are now indicating Wilma may not hit Florida until Tuesday. What are the chances that Wilma will somehow move north and affect the Florida Panhandle, or portions of the Gulf Coast further west? Less than 1 in 1000. As we approach winter in the Northern Hemisphere, westerly winds associated with the Jet Stream move far to the south, making it very difficult for any storm to go any direction but east or northeast once it gets into the Gulf of Mexico.

After Florida, then what?
There is no change to the forecast. After crossing Florida, Wilma should bring tropical storm force winds to the northern Bahama Islands. Wilma should pass well offshore North Carolina, but close enough to bring tropical storm force winds to the Outer Banks. Wilma is expected to merge with a large low pressure system as she approaches Maine or Nova Scotia next week, and could bring tropical storm force winds to Cape Cod, Maine, and the Canadian Maritime provinces.

What's behind Wilma?
There is a large area of disorganized thunderstorms near 13N 63W, about 500 miles south-southeast of Puerto Rico. This area has gotten better organized since yesterday, and has some potential for slow development as it moves northwest towards Haiti. This system is primarily a threat to Haiti, eastern Cuba, and the Bahamas, and should recurve out to sea thereafter.

I'll be back this afternoon with the lastest. The Mexican weather service's web site is overloaded, so I am not including any links pointing to Cancun radar or other Mexican weather data.

Jeff Masters

Wilma: nightmare for Mexico

By: JeffMasters, 8:44 PM GMT on October 20, 2005

Hurricane Wilma made its expected turn northwest, and is now headed towards Cozumel Island as an extremely dangerous Category 4 hurricane capable of massive destruction. A new hurricane hunter plane arrived at the center at 2:45 pm EDT, and found a central pressure of 918 mb and surface winds of 150 mph. The 4:16 pm report had the same pressure and winds, so Wilma has leveled out in intensity. Wilma has completed an eyewall replacement cycle, and now has a large 40 mile diameter eye. Some intensification is likely the next 18 hours before Wilma comes ashore in the Yucatan. It is possible Wilma can eclipse its record 882 mb pressure, but she probably will not have enough time to do that.


FIgure 1. Topography of the ocean bottom. Where a long expanse of shallow waters over the Continental Shelf (light blue) exist next to the coast, one can expect increased storm surge potential. The waters off the coast of Cancun/Cozumel are quite deep, limiting the maximum potential storm surge to about 11 feet. The Continental Shelf is quite extensive off the west coast of Florida, making that region prone to large storm surges. Image credit: NOAA.

Wilma's impact on Mexico
Wilma's impact on Mexico is likely to be catastrophic. A 50-mile wide stretch of coast will receive Category 4 to 5 sustained winds of over 150 mph, causing incredible damage. As Wilma sits in place for two days, the long duration of high winds will cause far more damage than a quickly moving storm would. The long duration extreme winds will probably cause some of the worst wind damage ever seen in a hurricane. The storm surge will not be as much as a problem, because deep water just offshore will prevent a huge storm surge from piling up. Still, the expected storm surge of up to 11 feet will cause widespread damage to coastal structures.In adddition, rainfall amounts of 15 - 25 will cause serious flooding. Wilma is likely to be Mexico's worst weather disaster in history.


Figure 2. Computer model tracks for Hurricane Wilma.

Where will Wilma go?
A trough of low pressure moving across the central U.S. has turned Wilma more to the northwest today, on a track towards Cozumel Island. The lastest 12Z (8am EDT) runs of all four major models used to track hurricanes--the GFS, GFDL, NOGAPS, and UKMET--agree on a landfall on Mexico's Yucatan Peninsula Friday, followed by a one to two day period of slow and erratic movement over land. By Sunday, strong westerly winds fill in behind the trough and pick up Wilma, and move her across South Florida by Monday. Once Wilma does make the crossing from Mexico to Florida, I expect little change in strength. While the waters are still warm enough to support intensification, this will be offset by increasing wind shear associated with the westerly winds driving Wilma.

How believable is all this? As we've seen many times this hurricane season, when the models come into alignment, it's usually a good sign that the forecast is correct. This is particularly true when data from the NOAA jet is used to initialize the models, which is the case here. However, in a case where the steering currents are weak, there is much less confidence. In addition, just a small 100 mile error in forecast means the difference between Wilma staying over warm waters and maintaining its intensity, or moving ashore and weakening significantly. The Canadian model (which has not performed well with Wilma) is forecasting that she will stay primarily over water the next three days.

Given all these factors, I'd give Wilma a 10% chance of arriving on the Florida west coast as a Category 3 or higher storm, 20% as a Category 2, 40% as a Category 1, and 30% as a tropical storm. On Florida's east coast, knock these value down by half a Category (10 - 15 mph).

After Florida, then what?
There is no change to the forecast. After crossing Florida, Wilma is threat to the northern Bahama Islands. Wilma should pass well offshore North Carolina, but close enough to bring tropical storm force winds to the Outer Banks. Wilma is expected to merge with a large low pressure system as she approaches Maine or Nova Scotia next week, and could bring tropical storm force winds to Cape Cod, Maine, and the Canadian Maritime provinces.

What's behind Wilma?
There is a large area of disorganized thunderstorms near 12N 57W, about 300 miles east of the Leeward Islands. Wind shear is too high to permit development of this area over the next day or two.

I'll be back tomorrow with the lastest. For those of you in Florida looking for storm surge maps of your county, check out the floridadisaster.org website.

Jeff Masters

Wilma aims devastating blow at Mexico

By: JeffMasters, 1:52 PM GMT on October 20, 2005

Hurricane Wilma continues across the western Caribbean towards Mexico as a extremely dangerous Category 4 hurricane capable of massive destruction. Wilma is currently undergoing a collapse of her inner eyewall, which will cause a short weakening trend that may last the remainder of the day. The inner eyewall of eight miles diameter is collapsing, and a new eyewall of 40 miles diameter is forming. This will reduce Wilma's peak winds to perhaps 135 mph today, at the low end of Category 4 strength. We'll have to wait until the next hurricane hunter mission arrives around 4 pm today to verify if this is the case.

As Wilma's eye reforms at a much larger size, the hurricane should begin to intensify again, and a return to Category 5 strength by Friday afternoon is a possibility. The larger eye will result in a much larger area being exposed to the extreme winds of the eyewall. If Wilma makes landfall along the Yucatan Peninsula, a stretch of coast perhaps 50 miles long will experience extreme damage.


Figure 1. Computer model tracks for Hurricane Wilma.

Where will Wilma go?
There is still a high degree of uncertainty in the forecast for Wilma. NHC has not adjusted the official forecast much the past few days, which is wise when the computer models are having difficulty. A trough of low pressure moving across the central U.S. should turn Wilma northwest today towards Cozumel Island, and then due north by tomorrow. However, once Wilma reaches the vicinity of Cancun and Cozumel, the storm is expected to slow to a crawl or stall for 12 - 48 hours. This will result in the northeast tip of the Yucatan Peninsula receiving a horrific pounding, particularly if the eye comes ashore. This weekend is a very bad weekend to be a tourist in Cancun.

Finally, by Saturday, strong westerly winds will build in behind the trough and carry Wilma rapidly northeastward across South Florida or the waters between Florida and Cuba.
The absolutely critical thing is--where will Wilma stall out? The GFDL model believes Wilma will push inland over the tip of the Yucatan, and spend two days overland, and weaken to a tropical storm. The UKMET model believes Wilma will stall in the Yucatan Channel, and not lose much strength. The other models have modest variations on these two themes. The difference in postions is only 100 miles or so. This is impossible to reliably forecast even 12 hours in advance, given the weak steering currents that are likely to exist Friday. Will will just have to wait and see what happens. Very small changes in storm position will cause huge changes in Wilma's intensity.

A long encounter with the Yucatan Peninsula would cause a serious disruption of the hurricane. While the waters are still warm enough to support intensification once she starts moving through the Gulf of Mexico towards Florida, there will be increasing wind shear associated with the westerly winds driving Wilma that will inhibit intensification. In addition, Wilma will only have a day or so to intensify, as the westerly winds will accelerate her to a forward speed of about 30 mph once she approaches Florida. Wilma's likely intensity once she reaches Florida is tropical storm to Category 3 strength.


Figure 2. Storm surge map for the southwest coast of Florida.

What kind of storm surge might affect Florida?
One can see from the storm surge map above that the southwest coast of Florida is very prone to high storm surges. This is because the Continental Shelf extends about 100 miles offshore, creating a very shallow area for the storm surge waters to build up in. If Wilma does hit the southwest coast of Florida as a Category 3 hurricane, which is the upper end of the intensity I think is likely, a 10 - 16 foot storm surge could flood most of Naples and all of Marco. Given the expected high forward speed of the hurricane at landfall in Florida--25 to 30 mph--regions to the south side of where the eye makes landfall will receive far greater wind damage and storm surge than is typical for a hurricane.

After Florida, then what?
After crossing Florida, Wilma is threat to the northern Bahama Islands. Wilma should pass well offshore North Carolina, but close enough to bring tropical storm force winds to the Outer Banks. Wilma is expected to merge with a large low pressure system as she approaches Maine of Nova Scotia about five days from now, and could bring tropical storm force winds to New England and the Canadian Maritime provinces.

I'll be back this afternoon about 4 pm EDT with an update on the latest, and post a storm surge map for the Keys if I can locate one.

Jeff Masters

Wilma's forecast highly uncertain

By: JeffMasters, 2:41 AM GMT on October 20, 2005

Just a quick update on the latest model runs: The 18Z (2 pm EDT) runs of the GFS and GFDL models have swung back towards Florida, and predict that the Yucatan may only get a quick (but severe) blow. The amount of weakening that might happen with Wilma over the Yucatan for just 12 hours or so is difficult to gauge. Also, there is the possibility of a threat to New England--the latest GFDL model run has Wilma hitting the Cape Cod area as a Category 2 hurricane on Monday night. I'll wait for the 00Z (8pm EDT) runs of the models that will be available in the morning before commenting more. The degree of uncertainty in both the track and intensity forecast of Wilma remains very high. The remainder of my blog from 5pm is below, unchanged.


Hurricane Wilma continues across the western Caribbean towards Mexico as a Category 5 hurricane. The Hurricane Hunters reached the storm at 2:06 pm EDT, and reported a pressure of 892 mb, ten mb higher than the Atlantic record lowest pressure of 882 mb set this morning. The 3:56 pm EDT hurricane eye report showed the same pressure, 892 mb. Peak winds measured at flight level were 141 knots in the southern eyewall, compared to 162 knots measured this morning. Infrared satellite imagery shows that the cloud tops have warmed a bit since this morning, and Wilma is a weaker storm--but still a Category 5 capable of catastrophic damage. The eye diameter measured by the hurricane hunters was still a very tiny 5 nm, and an second concentric eyewall with diameter 10 nm has formed. This indicates that Wilma may soon undergo an eyewall replacement cycle, and will weaken to a Category 4 storm.


Figure 1. Computer model tracks for Hurricane Wilma.

Where will Wilma go?
There is now a high degree of uncertainty in the forecast for Wilma. NHC has not adjusted the official forecast much with the 5 pm advisory, other than to slow down Wilma a bit. However, a major shift in the model guidance occurred with the just completed 12Z (8 am) runs, that may force NHC to make major modifications to the official forecast if further model runs continue to show this shift. Three of the top models--the GFS, GFDL, and UKMET models--now show that the trough of low pressure that was expected to pull Wilma sharply northwards and then northeast across Florida is progressing slower than expected, and will not dig as far south. If this forecast verifies, it would be very bad news for Mexico. Wilma may not pass east of Mexico through the Yucatan Channel as originally thought, and may instead make a landfall on the Yucatan Peninsula near Cozumel or Cancun Island on Thursday night or Friday morning, probably as a Category 4 hurricane.

However, this would be very good news for Florida. A long encounter with the Yucatan Peninsula would cause a serious disruption of the hurricane, and make it unlikely that Wilma could affect Florida as a major hurricane. A hit on southwest Florida as a Category 1 or 2 hurricane would be more likely, and the arrival of the hurricane would be delayed until Sunday. So, if I lived in Florida and was thinking about evacuating today, I would wait another day and see what the forecast tomorrow brings. Keep in mind, though, that the NOGAPS model, which is one of the top four models for tracking hurricanes, is still showing that Wilma will pass through the Yucatan Channel and a make landfall in southwest Florida as a major hurricane. The Canadian model is showing this as well. And the worst possible scenario, where Wilma makes a direct hit on Cancun but only spends a few short hours over the Yucatan and does not significantly weaken, is also a possibility.

Conditions on the Yucatan
Here's an email I received from wunderphotographer cleo85 , who is in the Yucatan and took the photo shown below. She has promised to post photos and send reports as her situation permits:

"Here is the Paamul [Yucatan Peninsula] update. After a very cloudy morning we did have some blue sky around 11:00am CDT. Now at 2:00pm CDT the Sky is almost overcast with picturesque clouds. There are a few light showers. We have a light breeze from north with winds what feel more and more warmer. The morning [5am CDT] showed 76 Fahrenheit now we have 88. Paamul is boarding up and will evacuate tomorrow. There is a confusion were to go since some of the newest computer models showing landfall on the Yucatan with a turn around and going back to the Caribbean. I was told the mood in the city of Playa del Carmen changed from almost ignorance two days ago to panic right now. There is no gasoline or diesel anywhere between Cancun and Tulum. Groceries seams to be tight. Batteries are out. There is price poaching going on. The Newspapers do their best to bring the panic up."

Jeff Masters

Wilma: dramatic change in forecast track?

By: JeffMasters, 7:37 PM GMT on October 19, 2005

Hurricane Wilma continues across the western Caribbean towards Mexico as a Category 5 hurricane. The Hurricane Hunters reached the storm at 2:06 pm EDT, and reported a pressure of 892 mb, ten mb higher than the Atlantic record lowest pressure of 882 mb set this morning. The 3:56 pm EDT hurricane eye report showed the same pressure, 892 mb. Peak winds measured at flight level were 141 knots in the southern eyewall, compared to 162 knots measured this morning. Infrared satellite imagery shows that the cloud tops have warmed a bit since this morning, and Wilma is a weaker storm--but still a Category 5 capable of catastrophic damage. The eye diameter measured by the hurricane hunters was still a very tiny 5 nm, and an second concentric eyewall with diameter 10 nm has formed. This indicates that Wilma may soon undergo an eyewall replacement cycle, and will weaken to a Category 4 storm.


Figure 1. Computer model tracks for Hurricane Wilma.

Where will Wilma go?
There is now a high degree of uncertainty in the forecast for Wilma. NHC has not adjusted the official forecast much with the 5 pm advisory, other than to slow down Wilma a bit. However, a major shift in the model guidance occurred with the just completed 12Z (8 am) runs, that may force NHC to make major modifications to the official forecast if further model runs continue to show this shift. Three of the top models--the GFS, GFDL, and UKMET models--now show that the trough of low pressure that was expected to pull Wilma sharply northwards and then northeast across Florida is progressing slower than expected, and will not dig as far south. If this forecast verifies, it would be very bad news for Mexico. Wilma may not pass east of Mexico through the Yucatan Channel as originally thought, and may instead make a landfall on the Yucatan Peninsula near Cozumel or Cancun Island on Thursday night or Friday morning, probably as a Category 4 hurricane.

However, this would be very good news for Florida. Any encounter with the Yucatan Peninsula would cause a serious disruption of the hurricane, and make it unlikely that Wilma could affect Florida as a major hurricane. A hit on southwest Florida as a Category 1 or 2 hurricane would be most likely, and the arrival of the hurricane would be delayed until Sunday. It is quite possible that Wilma would not affect Florida as a hurricane at all; the GFDL model forecasts that Wilma will spend three days over Mexico and emerge off the coast as a tropical storm and pass south of Cuba. So, if I lived in Florida and was thinking about evacuating today, I would wait another day and see what the forecast tomorrow brings. Keep in mind, though, that the NOGAPS model, which is one of the top four models for tracking hurricanes, is still showing that Wilma will pass through the Yucatan Channel and a make landfall in southwest Florida as a major hurricane. The Canadian model is showing this as well.

I'll have another update tonight, as conditions warrant.

Conditions on the Yucatan
Here's an email I received from wunderphotographer cleo85 , who is in the Yucatan and took the photo shown below. She has promised to post photos and send reports as her situation permits:

"Here is the Paamul [Yucatan Peninsula] update. After a very cloudy morning we did have some blue sky around 11:00am CDT. Now at 2:00pm CDT the Sky is almost overcast with picturesque clouds. There are a few light showers. We have a light breeze from north with winds what feel more and more warmer. The morning [5am CDT] showed 76 Fahrenheit now we have 88. Paamul is boarding up and will evacuate tomorrow. There is a confusion were to go since some of the newest computer models showing landfall on the Yucatan with a turn around and going back to the Caribbean. I was told the mood in the city of Playa del Carmen changed from almost ignorance two days ago to panic right now. There is no gasoline or diesel anywhere between Cancun and Tulum. Groceries seams to be tight. Batteries are out. There is price poaching going on. The Newspapers do their best to bring the panic up."

Jeff Masters

Wilma: freak of nature

By: JeffMasters, 2:25 PM GMT on October 19, 2005

There has never been a hurricane like Wilma before. With an unbelievable round of intensification that saw the pressure drop 87 mb in just 12 hours, Wilma smashed the all-time record for lowest pressure in an Atlantic hurricane this morning. The 4 am hurricane hunter report put the pressure at 882 mb, easily besting the previous record of 888 mb set in Hurricane Gilbert of 1988. Since no hurricane hunter airplane has been in the eye since then, Wilma may be even stronger now. The eye diameter of Wilma during this round of intensification shrunk as low as 2 nautical miles, which may be the smallest eye diameter ever measured in a tropical cyclone. The only eye I could find close to that small in the records was a 3 nm one, the Category 4 Typhoon Jeliwat in 2000. It's amazing the hurricane hunters were even able to penetrate the eye--it's really tough to hit a 2 mile wide eye when you're flying crabbed over at a 30 degree yaw angle fighting horizontal flight level winds of 185 mph and severe turbulence. This is an incredibly compact, amazingly intense hurricane, the likes of which has never been seen in the Atlantic. The Hurricane Season of 2005 keeps topping itself with new firsts, and now boasts three of the five most intense hurricanes of all time--Katrina, Rita, and Wilma.

Where will Wilma go?
There is a lot of uncertainty about this, as usual. After last night's flight by the NOAA jet, the computer models have come into better agreement, forecasting a track northwest through the Yucatan Channel, and then northeast across southern Florida. Cuba will probably end up getting the worst of Wilma, particularly the western tip of Cuba, which could see a direct hit.

After Cuba comes Florida. The models are converging on a landfall over the sparsely populated Everglades, but Wilma could hit as far north as Sarasota or pass south of the Keys. In any case, I expect the evacuation order for non-residents in the Keys will be given today, and the Keys and residents of southwest Florida from Naples southward are at greatest risk from Wilma. Assuming Wilma does hit the Everglades as expected, the Gold Coast of Florida from Miami to West Palm Beach is in for a severe pounding after Wilma crosses south Florida.

How strong will Wilma be?
Hurricanes do not maintain Category 5 strength very long, and Wilma is unlikely to be at that strength when it clears the Yucatan Channel and turns northeast towards Florida. Combine with that the possible effects of weakening due to interaction of a landfall on the western tip of Cuba or the northeast tip of the Yucatan Peninsula, Wilma is likely to be a Category 3 or 4 hurricane as it starts bearing down on southwest Florida. When Wilma does make this turn, the winds that will be turning her will also be creating some significant wind shear, which will weaken the storm. Wilma will be moving fairly quickly, though, so the shear won't have a lot of time to weaken her. I'm guessing this weakening will be in the order of 10 - 20 mph.

The end result of all these factors will cause Wilma to hit southwest Florida in the Everglades as a Category 3 or weak Category 4 hurricane with winds in the 120 mph - 135 mph range. The Everglades are low and swampy, and passage over the this area does not weaken a hurricane as much as landfall further north over the Florida Peninsula. In the case of Hurricane Andrew, which passed across the Everglades on a reverse path, the hurricane started its traverse as a Category 5 hurricane with 170 mph winds and a 922 mb central pressure. By the time it emerged in the Gulf of Mexico, Andrew was a Category 3 hurricane with 130 mph winds and a central pressure of 951 mb. Andrew was a very small hurricane, and passage over the Everglades weakened it considerably. In the case of Hurricane Katrina earlier this year, the traverse of south Florida did not significantly weaken the storm. Katrina started its traverse of south Florida with a central pressure of 981 mb and 80 mph winds, and finished with a central pressure of 985 mb and 75 mph winds. Katrina was a much larger storm than Andrew, and more representative of the size Wilma is likely to have over Florida.

The closest analogue storm I can find in the archives is an October 1906 hurricane that looks remarkably similar. The 1906 hurricane formed in the western Caribbean, brushed Cuba as it passed through the Yucatan Channel, then crossed extreme southern Florida, passing from the Everglades to Fort Lauderdale. This hurricane weakened from a Category 4 hurricane with 135 mph winds to a Category 3 hurricane with 125 mph winds as it crossed Florida.

I think we can expect Wilma to behave in a similar fashion as the 1906 hurricane, and lose about 10 mph in its peak winds due to passage over the Everglades. Wilma may lose an additional 5 mph due to the continued action of the expected higher wind shear. This would make Wilma a strong Category 2 or weak Category 3 hurricane over Miami/Fort Lauderdale with peak winds of 105 - 120 mph. A really big question is how far out will the hurricane force winds extend? Wilma is currently a very compact storm with hurricane force winds extending out only 15 miles from the center. If she maintains this compact structure, damage in Florida will be limited to a very small area. However, with three days remaining over very warm waters, Wilma will expand its windfield somewhat, so that hurricane force winds will extend out 60 - 90 miles from the center. This will be enough to cause severe damage to the Gold Coast in the $10 - $20 billion range. If Wilma follows the path I expect, this will be the worst hurricane in the Miami Beach/Fort Lauderdale area since 1965's Hurricane Betsy.

Keep in mind that the average error in a hurricane track forecasts four days is over 200 miles, and that our skill in making intensity forecasts is low--as witnessed in Wilma's incredible ascent from a Category 1 to Category 5 hurricane in just 12 hours.

What has Wilma done so far?
Wilma has claimed her first victims; up to ten are dead on Haiti in landslides triggered by the hurricane's heavy rains. Mudslides and flooding are also serious problems in the southeastern Cuban provinces of Guantánamo, Santiago de Cuba and Granma. Nearly 13 inches (33 cm) of rain was measured at Santiago de Cuba yesterday. The Cuban newspaper Granma is reporting 255 homes damaged or destroyed in that town, and sections of the Sevilla-Guamá-Santiago de Cuba highway impassable due to swollen rivers, while landslides have blocked the Cordovelo-Loma Blanca road. In Jamaica, widespread flooding has cut off several communities and caused millions in damage to roads. All schools are closed on the island through Thursday and hospitals are taking only emergency patients. Rainfall rates as high as two inches per hour were observed in the Blue Mountains of south-central Jamaica yesterday.

I'll have another update this afternoon, there's a lot more to talk about.

Jeff Masters

Wilma: freak of nature

By: JeffMasters, 10:59 AM GMT on October 19, 2005

There has never been a hurricane like Wilma before. With an unbelievable round of intensification that saw the pressure drop 87 mb in just 12 hours, Wilma smashed the all-time record for lowest pressure in an Atlantic hurricane this morning. The 4 am hurricane hunter report put the pressure at 882 mb, easily besting the previous record of 888 mb set in Hurricane Gilbert of 1988. And since no hurricane hunter airplane has been in the eye since then, Wilma may be even stronger now. The eye diameter of Wilma during this round of intense shrunk as low as 2 nautical miles, which may be the smallest eye diameter ever measured in a tropical cyclone. The only eye that small I could find in the records was a 3 nm the Category 4 Typhoon Jeliwat achieved in 2000. It's amazing the hurricane hunters were even able to penetrate the eye--it's really tough to hit a 2 mile wide eye when you're flying crabbed over at a 30 degree yaw angle fighting horizontal flight level winds of 185 mph and severe turbulence. This is an incredibly compact, amazingly intense hurricane, the likes of which has never been seen in the Atlantic. The Hurricane Season of 2005 keeps topping itself with new firsts, and now boasts three of the five most intense hurricanes of all time--Katrina, Rita, and Wilma.

Where will Wilma go?
There is a lot of uncertainty about this, as usual. After last night's flight by the NOAA jet, the computer models have come into better agreement, forecasting a track northwest through the Yucatan Channel, and then northeast across southern Florida. Cuba will probably end up getting the worst of Wilma, particularly the western tip of Cuba, which could see a direct hit.

After Cuba comes Florida. The models are converging on a landfall over the sparsely populated Everglades, but Wilma could hit as far north as Sarasota or pass south of the Keys. In any case, I expect the evaction order for non-residents in the Keys will be given today, and the Keys and residents of southwest Florida from Naples southward are at greatest risk from Wilma. Assuming Wilma does hit the Everglades as expected, the Gold Coast of Florida from Miami to West Palm Beach are in for a severe pounding after Wilma crosses south Florida.

How strong will Wilma be?
Hurricanes do not maintain Category 5 strength very long, and Wilma is unlikely to be at that strength when it clears the Yucatan Channel and turns northeast towards Florida. Combine with that the possible effects of weakening due to interaction or a landfall on the western tip of Cuba or the northeast tip of the Yucatan Peninsula, and Wilma is likely to be a Category 3 or 4 hurricane as it starts bearing down on southwest Florida. When Wilma does make this turn, the winds that will be turning her will also be creating some significant wind shear, which will weaken the storm. Wilma will be moving fairly quickly, though, so the shear won't have a lot of time to weaken her. I'm guessing this weakening will be in the order of 10 - 20 mph.

The end result of all these factors will cause Wilma to hit southwest Florida in the Everglades as a Category 3 or weak Category 4 hurricane with winds in the 120 mph - 135 mph range. The Everglades are low and swampy, and passage over the this area does not weaken a hurricane as much as landfall further north over the Florida Peninsula. In the case of Hurricane Andrew, which passed across the Everglades on a reverse path, the hurricane started its traverse as a Category 5 hurricane with 170 mph winds and a 922 mb central pressure. By the time it emerged in the Gulf of Mexico, Andrew was a Category 3 hurricane with 130 mph winds and a central pressure of 951 mb. Andrew was a very small hurricane, and passage over the Everglades weakened it considerably. In the case of Hurricane Katrina earlier this year, the traverse of south Florida did not
significantly weaken the storm. Katrina started its traverse of south Florida with a central pressure of 981 mb and 75 mph winds, and finished with a central pressure of 985 mb and 75 mph winds. Katrina was a much larger storm than Andrew, and more representative of the size Wilma is likely to have over Florida.

The closest analogue storm I can find in the archives to Wilma is an href=http://www.wunderground.com/hurricane/at190608.asp>October 1906 hurricane that looks remarkably similar. The 1906 hurricane formed in the western Caribbean, brushed Cuba as it passed through the Yucatan Channel, then crossed extreme southern Florida, passing from the
Everglades to Fort Lauderdale. This hurricane weakened from a Category 4 hurricane with 135 mph winds to a Category 3 hurricane with 125 mph winds as it crossed Florida.

I think we can expect Wilma to behave in a similar fashion to the 1906 hurricane, and lose about 10 mph in its peak winds due to passage over the Everglades. Wilma may lose an additional 5 mph due to the continued action of the expected higher wind shear. This would make Wilma a strong Category 2 or weak Category 3 hurricane over Miami/Fort Lauderdale with peak winds of 105 - 120 mph. A really big question is how far out will the hurricane force winds extend? Wilma is currently a very compact storm with
hurricane force winds extending out only 15 miles from the center. If she maintains this compact structure, damage in Florida will be limited to a very small area. However, with three days remaining over very warm waters, Wilma will doubtless expand its windfield somewhat, so that hurricane force winds will extend out 50 - 80 miles from the center. This will be enough to cause severe damage to the Gold Coast in the $10 - $20 billion range. If Wilma follows the path I expect, this will be the worst hurricane in Miami Beach/Fort Lauderdale area since 1965's Hurricane Betsy.

Keep in mind that the average error in a hurricane track forecasts four days is over 200 miles, and that our skill in making intensity forecasts is low--as witnessed in Wilma's incredible ascent from a Category 1 to Category 5 hurricane in just 12 hours.

What has Wilma done so far?
Wilma has claimed her first victims; up to ten are dead on Haiti in landslides triggered by the hurricane's heavy rains. Mudslides and flooding are also serious problems in the southeastern Cuban provinces of Guantánamo, Santiago de Cuba and Granma. Nearly 13 inches (33 cm) of rain was measured at Santiago de Cuba yesterday. The Cuban newspaper Granma is reporting 255 homes damaged or destroyed in that town, and sections of the Sevilla-Guamá-Santiago de Cuba highway impassable due to swollen rivers, while landslides have blocked the Cordovelo-Loma Blanca road. In Jamaica, widespread flooding has cut off several communities and caused millions in damage to roads. All schools are closed on the island through Thursday and hospitals are taking only emergency patients. Rainfall rates as high as two inches per hour were observed in the Blue Mountains of south-central Jamaica yesterday.

I'll have another update this afternoon, there's a lot more to talk about.

Jeff Masters

Wlima intensifying rapidly

By: JeffMasters, 10:19 PM GMT on October 18, 2005

Wilma's rapid intensification phase continues, with another 9 mb drop in the past 1 1/2 hours, for a total of 16 mb in the past three hours. The 7:09 EDT hurricane hunter report found a pressure of 954 mb, and maximum flight level winds at 5000 feet of 101 knots (116 mph). Wilma is a solid Category 2 hurricane, and probably on her way to Category 3 status by early Wednesday morning. The Hurricane Hunters don't fly in Category 2 and stronger hurricanes at 5000 feet altitude very often; I wonder if the next eye penetration will be done at 10,000 feet.

Wilma has claimed her first victims; up to ten are dead on Haiti in landslides triggered by the hurricane's heavy rains. Mudslides and flooding are also serious problems in the southeastern Cuban provinces of Guantánamo, Santiago de Cuba and Granma. Nearly 13 inches (33 cm) of rain was measured at Santiago de Cuba since Wilma's rains began. The Cuban newspaper Granma is reporting 255 homes damaged or destroyed in that town, and sections of the Sevilla-Guamá-Santiago de Cuba highway impassable due to swollen rivers, while landslides have blocked the Cordovelo-Loma Blanca road. In Jamaica, widespread flooding has cut off several communities and caused millions in damage to roads. All schools are closed on the island through Thursday and hospitals are taking only emergency patients. Rainfall rates as high as two inches per hour have been observed in the Blue Mountains of south-central Jamaica this afternoon.

Wilma's eye diameter is now a very tiny 8 nm (9 miles), up one mile since last report, but still very small for a hurricane. It will be interesting to see how long Wilma can maintain an eye that small; I expect the eyewall will collapse by morning and an eyewall replacement cycle will begin, with Wilma leveling out at Category 3 strength. The eye is now very prominent on satellite imagery, and spiral banding and upper-level outflow continue to improve and cover a larger area.

The remainer of my 5pm discussion appears below, unchanged.

Wilma became a hurricane today, tying the record of 12 hurricanes in a season set in 1969. In that year, the last two hurricanes formed after October 30, so 2005 has a decent chance of breaking that record. I expect 2005 will also break the record of 21 total storms, which it now shares with the 1933 hurricane season.

The upper level environment looks excellent but not perfect for intensification, with low wind shear and two good outflow channels, one on the north side, and one on the southwest side. About five knots of wind shear is degrading the outflow pattern and symmetry on the northwest side, and there is still some dry air there for Wilma to contend with. Continued intensification into a Category 3 hurricane by Wednesday looks reasonable, and I'd give it a 40% chance Wilma makes it to Category 4 status by Friday. The GFDL is calling for a 922 mb Category 4 storm by Friday, but this forecast is probably overdone, as the GFDL has been consistently too aggressive with its intensity forecasts for Wilma. By Saturday, Wilma will be far enough north that wind shear from an upper-level trough of low pressure will reduce Wilma's winds by perhaps 20 mph.

Wilma is currently traversing an area of high oceanic heat content (see Figure 1), and this heat content will not significantly fall unless Wilma passes north of the Florida Keys. I would expect an additional 10 mph reduction in Wilma's winds if she makes landfall in Florida north of the Keys, due to the lower heat content of the water. So, expect landfall as a strong Category 2 hurricane if Wilma moves through the Keys, or as a weak Category 2 hurricane further north. Remember that hurricane intensity forecasts are poor, especially 3 - 5 days out, so Wilma's intensity could easily be a full Category higher or lower than this.


Figure 1. Total heat content of the ocean is high over the northwest Caribbean and the southern Gulf of Mexico south of 25 N latitude. Images credit: NOAA/AOML.

Jamaica continues to take a pounding from Wilma, but this should end tomorrow night as Wilma pulls away. The next area of concern is northern Honduras and Nicaragua, where rains of up to 12 inches are expected. However, the portions of these countries that will receive the heaviest rains are relatively flat, so I do not expect massive loss of life from flooding in the mountains.

Next on Wilma's list will be the Cayman Islands, but flooding is generally not life-threatening in that nation. Mexico and Cuba may escape serious damage if Wilma passes through the Yucatan Channel as forecast.


Figures 1. Computer model forecasts for Wilma.

Wilma started moving WNW at 8 mph today, as all the computer models predicted she would. The models are pretty unified, bringing Wilma through the Yucatan Channel or across the western tip of Cuba, and then northeastward into the Florida Keys or the west coast of Florida by the weekend. Two models (the UKMET and GFS) predict that Wilma will pass just south of the Keys. The furthest north model is the Canadian, which picks Sarasota for its landfall. The GFDL, NOGAPS, and the official NHC forecast are in the middle, with a landfall over the Everglades of Southwest Florida. The NOAA jet is scheduled to makes its first flight tonight, and tomorrow morning we should have a better idea of which part of Florida is at most risk. Climatology favors a more southern track, and I expect that we'll see the models converge on a more southerly track through the Keys in the runs we see Wednesday morning.

Elsewhere in the tropics, there is a large area of disturbed weather midway between Africa and the Leeward Islands. Upper level winds are not favorable for development of this area, which is also too close to the Equator. I'll be back with a update in the morning.

Jeff Masters

Hurricane Wilma: Category 1 and strengthening

By: JeffMasters, 9:06 PM GMT on October 18, 2005

Wilma became a hurricane today, tying the record of 12 hurricanes in a season set in 1969. In that year, the last two hurricanes formed after October 30, so 2005 has a decent chance of breaking that record. I expect 2005 will also break the record of 21 total storms, which it now shares with the 1933 hurricane season.

Wilma continues to intensify as a modest pace. The Hurricane Hunters at 4 pm EDT found a central pressure of 970 mb and flight level winds on the weaker (north) side of the hurricane that correspond to winds of 70 - 75 mph at the surface. Stronger winds probably exist elsewhere in the storm, but all indications are that this is a medium strength Category 1 hurricane. An eye has popped in and out of visible satellite imagery this afternoon, but is not yet evident as a warm spot on infrared satellite imagery. Spiral banding and upper-level outflow continue to improve and cover a larger area.

The upper level environment looks excellent but not perfect for intensification, with low wind shear and two good outflow channels, one on the north side, and one on the southwest side. About five knots of wind shear is degrading the outflow pattern and symmetry on the northwest side, and there is still some dry air there for Wilma to contend with. Continued intensification into a Category 3 hurricane by Wednesday looks reasonable, and I'd give it a 40% chance Wilma makes it to Category 4 status by Friday. The GFDL is calling for a 922 mb Category 4 storm by Friday, but this forecast is probably overdone, as the GFDL has been consistently too aggressive with its intensity forecasts for Wilma. By Saturday, Wilma will be far enough north that wind shear from an upper-level trough of low pressure will reduce Wilma's winds by perhaps 20 mph.

Wilma is currently traversing an area of high oceanic heat content (see Figure 1), and this heat content will not significantly fall unless Wilma passes north of the Florida Keys. I would expect an additional 10 mph reduction in Wilma's winds if she makes landfall in Florida north of the Keys, due to the lower heat content of the water. So, expect landfall as a strong Category 2 hurricane if Wilma moves through the Keys, or as a weak Category 2 hurricane further north. Remember that hurricane intensity forecasts are poor, especially 3 - 5 days out, so Wilma's intensity could easily be a full Category higher or lower than this.


Figure 1. Total heat content of the ocean is high over the northwest Caribbean and the southern Gulf of Mexico south of 25 N latitude. Images credit: NOAA/AOML.

Jamaica continues to take a pounding from Wilma, but this should end tomorrow night as Wilma pulls away. The next area of concern is northern Honduras and Nicaragua, where rains of up to 12 inches are expected. However, the portions of these countries that will receive the heaviest rains are relatively flat, so I do not expect massive loss of life from flooding in the mountains.

Next on Wilma's list will be the Cayman Islands, but flooding is generally not life-threatening in that nation. Mexico and Cuba may escape serious damage if Wilma passes through the Yucatan Channel as forecast.


Figures 1. Computer model forecasts for Wilma.

Wilma started moving WNW at 8 mph today, as all the computer models predicted she would. The models are pretty unified, bringing Wilma through the Yucatan Channel or across the western tip of Cuba, and then northeastward into the Florida Keys or the west coast of Florida by the weekend. Two models (the UKMET and GFS) predict that Wilma will pass just south of the Keys. The furthest north model is the Canadian, which picks Sarasota for its landfall. The GFDL, NOGAPS, and the official NHC forecast are in the middle, with a landfall over the Everglades of Southwest Florida. The NOAA jet is scheduled to makes its first flight tonight, and tomorrow morning we should have a better idea of which part of Florida is at most risk. Climatology favors a more southern track, and I expect that we'll see the models converge on a more southerly track through the Keys in the runs we see Wednesday morning.

Elsewhere in the tropics, there is a large area of disturbed weather midway between Africa and the Leeward Islands. Upper level winds are not favorable for development of this area, which is also too close to the Equator. I'll be back with a update in the morning.

Jeff Masters

Wilma: a hurricane today

By: JeffMasters, 1:57 PM GMT on October 18, 2005

Wilma continues to intensify. Satellite imagery shows a dense cirrus overcast (CDO) beginning to form and cover the center of the storm, which is characteristic of a tropical storm intent on becoming a hurricane. Spiral banding and upper-level outflow continue to improve and cover a larger area. Some wind shear and dry air are affecting the northwest side of the storm, but Wilma is gaining a more symmetric appearance characteristic of a hurricane. The hurricane hunters left the storm at 3 am EDT this morning and are not due back until about 3 pm EDT this afternoon, so we will have to wait until then to learn Wilma's true strength.

The upper level environment continues to look favorable for intensification, with low wind shear and an anti-cyclone on top generating good outflow on all sides except the norhtwest. Intensification into a Category 3 hurricane by Thursday still seems like a good bet. There is a small chance Wilma could make it to Category 4 status by Friday, but shear will start to increase by then as the upper-level trough of low pressure generates strong westerly winds over her. This shear will likely reduce Wilma's winds by at least 20 mph, and landfall in Florida as a strong Category 2 hurricane seems like a reasonble intensity forecast.

Steering currents are expected to remain weak today, and some erratic motion is possible. All of the forecast models predict a generally west or west-northwest motion over the next two days. Now that Wilma has stopped moving south, this gives me some confidence that this forecast is the correct one, and the danger to Honduras is considerably lessened. Only the northeast portion of Honduras should see heavy rains over ten inches, and since this part of the country is relatively flat, the threat of life-threatening flash flooding and mud slides like killed thousands in Hurricane Mitch and Hurricane Fifi is low. So far, northeastern Honduras has received only one to two inches of rain from Wilma.

The country that has taken the worst pounding so far from Wilma is Jamaica, where Wilma's rains have already caused millions of dollars of damage to the road infrastructure. Widespread flooding and road blockages due to mudslides are being reported, and will continue as Wilma stays essentially stationary or moves very slowly away from Jamaica today.

Next on Wilma's hit list will be Mexico and Cuba, who have already had their share of major hurricanes this season. Mexico is still cleaning up the damage from Hurricane Emily earlier this year, and Cuba took one of its worst hurricane pouundings ever during Hurricane Dennis in July. Heavy rains in the Cayman Islands, Belize, Nicaragua, and northern Guatemala may also create local flooding problems in those nations. If Wilma grows large enough to tap the Pacific as a source of moisture, Nicaragua and Costa Rica could also experience some moderate flooding problems.


Figures 1. Computer model forecasts for Wilma.

The models have reached a strong consensus that a low pressure system currently bringing rain to the western U.S. will move east and exert a strong pull on Wilma, turning her more northwest by Thursday, through the Yucatan Channel, and then northeastward into the Florida Keys or the west coast of Florida by the weekend. Most of the guidance shows the Keys to be the primary region at risk, but the GFDL model has moved its landfall point further north with its most recent run (2 am EDT), and puts the area between Sarasota and Fort Myers in the bullseye. The NOAA jet is scheduled to makes its first flight tonight, and tomorrow morning we should have a better idea of the reliability of the current model forecasts.

Elsewhere in the tropics, there is a large area of disturbed weather midway between Africa and the Leeward Islands. Upper level winds are not favorable for development of this area, which is also too close to the Equator. I'll be back with a update in this afternoon after the Hurricane Hunters report in.

Jeff Masters

Wilma--major threat to Honduras

By: JeffMasters, 9:34 PM GMT on October 17, 2005

Wilma is steadily intensifying. The hurricane hunters reached the storm at 4:05 pm EDT, finding maximum surface winds of 50 mph and a central pressure of 989 mb. Satellite imagery shows that deep convection is starting to wrap all the way around the center, and infrared imagery hints at a warm center spot where an eye may form by Tuesday. The hurricane hunters noted that spiral banding looked good, and satellite imagery also shows an impressive amount of spiral banding developing on all sides. The dry air intruding on the northwest side is starting to mix out, and upper-level outflow is well established on the south and east sides of the storm.

The upper level environment continues to look favorable for intensification, with low wind shear and an anti-cyclone on top generating good outflow. Intensification into a Category 3 hurricane by Thursday still seems like a good bet. Once Wilma gets further north into the Gulf of Mexico, shear increases as a upper-level trough of low pressure generates strong westerly winds over Wilma. This shear will likely reduce Wilma's winds by at least 20 mph.


Figure 1. Track of 1974's Hurricane Fifi, which killed over 8000 people in Honduras.

Steering currents are expected to remain weak the next two days, and some erratic motion is possible. All of the forecast models predict a generally west or west-northwest motion over the next two days. However, today's southerly motion at 2 - 5 mph is something none of the forecast models called for, except the UKMET model. This gives me some concern that Wilma may pass close enough to Honduras to create heavy downpours of 10 - 15 inches that would cause severe flooding and significant mudslides. It doesn't take a very strong hurricane to kill thousands in Honduras, as 1974's Category 2 Hurricane Fifi demonstrated. Hurricane Fifi moved along the north of the coast of Honduras at about latitude 16.1, bringing heavy rains of up to 24 inches that killed 8000 people. Wilma is currently at latitude 15.9, and looks like it will also be a Category 2 hurricane as it passes along the north shore of Honduras. Heavy rains will begin in northeastern Honduras tonight, and may well continue for three days. Hopefully, Wilma will pull north as forecast and not subject the entire coast of Honduras to flooding rains as Fifi did. I do expect severe flooding in northeast Honduras that will cause heavy loss of life. Better disaster prevention measures were implemented in Honduras after the devastation Hurricane Mitch wrought in 1998, so hopefully the government will be able to get the people in flood-prone areas to safe shelter and reduce the death toll.

Wilma presents it's next greatest threat to Mexico, which is still cleaning up the damage from Hurricane Emily earlier this year. Heavy rains in Belize, Nicaragua, and northern Guatemala may also create flooding problems in those nations. If Wilma grows large enough to tap the Pacific as a source of moisture, El Salvador and the southern portions of Guatemala hard-hit by Hurricane Stan may get addtional rains that could be a problem. However, the computer models are not indicating that this will happen.

The models have reached more of a consensus this afternoon on the longer term track of Wilma. After struggling mightily to properly resolve a weak trough of low pressure over the central U.S., the models now agree that this trough should be able to pull Wilma west-northwest by Tuesday. Later in the week, a strong low pressure system currently bringing rain to southern California is expected to move east and exert a strong pull on Wilma, turning her more northwest by Thursday. After Wilma makes a landfall near Cancun/Cozumel or a passage through the Yucatan Channel, the trough is expected to pull her northeastward, resulting in a landfall on the west coast of Florida somewhere between Key West and Tampa. The timing and location of the U.S. landfall forecasts look like this:

Candian model: Friday, Sarasota
GFS model: Saturday, Florida Keys
NOGAPS model: Saturday, Florida Keys
GFDL model: Sunday, Tampa
UKMET model: Wilma stalls out over the Yucatan at day 6; eventual track after that not known.

The NOAA jet is scheduled to make its first flight Tuesday afternoon, and we'll have a much better idea of the likely U.S. landfall point on Wednesday morning.

Elsewhere in the tropics, nothing else is happening. I'll be back with a update in the morning about 10 am EDT.

Jeff Masters

Wilma's formation marks busiest hurricane season ever

By: JeffMasters, 2:00 PM GMT on October 17, 2005

The historic Hurricane Season of 2005 now has the distinction of being the busiest ever. Wilma's formation this morning gives 2005 21 named storms, equaling the mark set in 1933. With over six weeks still left in hurricane season, that mark will likely be surpassed.

After struggling for two days as a tropical depression, Wilma finally put together a sustained, intense burst of deep convection this morning that propelled her to tropical storm strength. This convective burst is only on the south side of the center of circulation, and the storm still has a long way to go before attaining hurricane status. Dry air is intruding on the northwest side, and the upper level outflow is established only on the east side of the storm. Still, the overall satellite signature is rather ominous and impressive, with a large envelope of thickening clouds on the eastern side of the storm. The wind shear is still very low--about five knots, and expected to stay low. The last hurricane hunter mission left the storm at 4:30 pm EDT Sunday, so the exact strength of the storm is not known at this point. There is not another mission scheduled until 2 pm EDT today. The NOAA jet is scheduled to make its first flight Tuesday afternoon.

The forecast guidance still predicts that this will be Hurricane Wilma by Wednesday. Wilma will spend the next three days in a low-shear environment with water temperatures of 30 C (86 F), which should allow intensification into at least a Category 2 storm, perhaps even a Category 3. Wilma reminds me of Rita, which spent about three days trying to organize in the Bahamas before finally solidifying its inner core and rapidly intensifying. This storm may behave similarly.


Figure 1. Computer model tracks for Wilma.

Steering currents are expected to remain weak the next two days, and some erratic motion is possible. All of the forecast models predict a generally west or west-northwest motion over the next two days. However, this morning's southerly motion at 5 mph is something none of the forecast models have called for. This gives me some concern about this storm severely impacting Honduras and its neighboring Central American countries, particularly Guatemala, which is still reeling from the impact of Hurricane Stan. As Wilma grows in size, a continued southward motion may allow it to start pulling in a deep layer of moisture from the Pacific Ocean, which would trigger heavy rains over the regions of Guatemala and El Salvador hardest hit by Stan. These rains would probably be in the 3 - 5 inch range--nowhere near the devastating 15 - 25 inches seen from Stan, but still high enough to trigger new mudslides on the destabilized slopes of the steep mountainsides.

The computer models have been having huge difficulties with a weak trough of low pressure over the U.S. that may be able to pull Wilma northwards. Last night's 00Z (8pm) models runs of the five models we plot on our computer model tracking chart all failed to properly initialize this trough, calling for it to be weaker than is really is. This resulted in a set of model tracks with a much further west track for Wilma, bringing her into Belize or the Yucatan later in the week. This morning's 06Z (2am EDT) runs of the GFDL and GFS model did properly initialize this trough, and these new model runs now indicate a sharp turn to the northwest and north across western Cuba. Given that the models are not currently handling the southerly motion of the storm, I would be hesitant to believe this forecast yet. All the computer models were calling for a similar northward track for Hurricane Mitch in October 1998, and it ended up wandering south and getting stuck off of the coast of Honduras. However, a second much stronger low pressure system currrently bringing rain to southern California is expected to move east this week and push a trough far enough south to pull the storm northwards later in the week, if the current trough can't do the job. The west coast of Florida still appears likely to receive a hit from Wilma. The timing and severity of this blow are impossible to call at this point until Wilma starts her northwestward turn.

Elsewhere in the tropics, nothing else is happening. I'll be back with a update this afternoon about 4pm, when the latest set of model guidance will be in and the Hurricane Hunters will have visited the storm.

Stan revisited
The official death toll from Hurricane Stan in Guatemala is 654, with 830 people missing. Another 133 people have died in Mexico, El Salvador, Costa Rica, Nicaragua and Honduras, making Stan one of the 30 deadliest hurricanes in history. Over 3.5 million Guatemlans have been affected by the storm, with nearly 5,000 homes destroyed and hundreds of thousands damaged. Many corn, sesame and sorghum crops along the south coast were been destroyed, and Guatemala will need extensive long-term aid to recover from this immense disaster. The Guatemalan Red Cross has made available a way to donate online via the Active network (www.active.com). With the earthquake disaster in Pakistan and Hurricane Katrina competing for attention, donations are urgently needed in Guatemala.


Figure 2. View of the Lake Atitlan region of Guatemala, looking south towards the Pacific Ocean. The circulation of Hurricane Stan pulled a deep layer of moist air off of the Pacific Ocean, which triggered heavy rains of 15 - 25 inches. A huge mudslide roared down the slope of the Toliman volcano and buried the town of Panabaj, killing over 400 Guatemalans. Note the brownish deforested areas on the slopes of the Toliman volcano; the lack of vegetation on the slopes contributed to many of the mudslides from this disaster.


Jeff Masters

No Wilma tonight

By: JeffMasters, 1:49 AM GMT on October 17, 2005

Tropical Depression 24 remains unimpressive tonight; satellite imagery continues to slow a large and poorly organized system that is not yet a tropical storm. The wind shear above the storm is still very low--less than five knots--but the upper-level anticyclone that was on top has become less well defined, and dry air continues to intrude into the northwest side of the storm. The last hurricane hunter mission left the storm at 4:30 pm EDT today, so the exact strength of the storm is not known at this point. There is not another mission scheduled until 2 pm EDT Monday. The NOAA jet is scheduled to make its first flight Tuesday afternoon.

The forecast guidance still predicts that this will be Tropical Storm Wilma on Monday, and Hurricane Wilma by Wednesday. This storm reminds me of Rita, which spent about three days trying to organize in the Bahamas before finally solidifying its inner core and rapidly intensifying. This storm may behave similarly, and intensificatiion into a major hurricane by late in the week is a possibility that several of the computer models are calling for.


Figure 1. Historical tracks of tropical depressions that have formed in the western Caribbean in October.

Steering currents are expected to remain weak the next three days, and some erratic motion is possible. However, a mostly west or west-northwest should result in a landfall on the Yucatan or Belize late in the week. A weak trough that was expected to deflect the storm to the north before this happened is now forecast to be too weak to significantly affect it. However, second a low pressure system currrently bringing rain to southern California is expected to move east this week and push a trough far enough south to pull the storm to the north and into the Gulf of Mexico late in the week. An eventual landfall on the west coast of Florida 7 - 8 days from now is expected. This is a typical track for October systems forming in the western Caribbean, as we can see from the historical track map shown in Figure 1. It still looks unlikely that this storm will get "stuck" in the Caribbean and drift southwest towards Honduras like Category 5 Hurricane Mitch did in October 1998. It also appears unlikely that Gulf Coast residents of Louisiana and Texas will receive a direct hit from this storm, although it is difficult to accurately forecast what might happen beyond five days when we are so poor at just three day forecasts.

Elsewhere in the tropics, nothing else is happening. I'll be back with a update in the morning about 9:30 am EDT.

Jeff Masters

TD 24 slow to organize

By: JeffMasters, 2:17 PM GMT on October 16, 2005

Tropical Depression 24 is slow to organize, in part due to some dry air on the northwest side that is inhibiting it. However, all the forecast guidance points to a very favorable environment for intensification starting Monday, and the dry air mixes out, shear decreases below 5 knots, and ocean temperatures beneath the storm remain near 29C.
All indications are that this will be Tropical Storm Wilma on Monday, and Hurricane Wilma by Wednesday. Intensificatiion into a major hurricane by late in the week is a distinct possibility.


Figure 1. Historical tracks of tropical depressions that have formed in the western Caribbean in October.

Steering currents are expected to remain weak the next two days, and the computer models are forecasting a slow movement to the west or west-southwest. After that, most of the models agree on a more northerly track towards Cuba as a trough of low pressure swinging across the U.S. exerts a pull on the system three days from now. A second trough of low pressure five days from now will create an additional pull, that should accelerate the storm quickly to the north or northeast. This is a typical track for October systems forming in the western Caribbean, as we can see from the historical track map shown in Figure 1. It is looking increasingly unlikely that this storm will get "stuck" in the Caribbean and drift southwest towards Honduras like Category 5 Hurricane Mitch did in October 1998.
Western Cuba, Mexico's Yucatan, and the west coast of Florida and Florida Keys are at greatest risk. It currently appears that Gulf Coast residents of Louisiana and Texas have little chance of being hit by this storm.

Elsewhere in the tropics, nothing else is happening. I'll be back with a update this evening around 9 pm.

Jeff Masters



There a

Here comes Wilma

By: JeffMasters, 9:17 PM GMT on October 15, 2005

Tropical Depression 24 is here, but it won't be called that for very long. All indications are that this will be Tropical Storm Wilma on Sunday, and Hurricane Wilma by Tuesday. The areal coverage of the deep convection continues to increase, low-level spiral banding has appeared, and upper-level outflow is now good on the west and north sides of the depression. The upper level anti-cyclone has overhead has grown better defined, and wind shear remains a low five knots.

Global computer models forecast that the shear will continue to remain low the next several days over the western Caribbean, where the depression is expected to remain. The chances of this storm growing to hurricane strength are high, and I expect this will be a major hurricane of a least Category 3 strength five days from now. The last three GFDL model runs have consistently been bringing the storm to major hurricane strength.


Figure 1. Historical tracks of tropical depressions that have formed in the western Caribbean in October.

Steering currents are expected to remain weak, and the computer models are forecasting a slow movement to the west or west-southwest the next three days. After that, most of the models agree on a more northerly track towards Cuba as a trough of low pressure swinging across the U.S. exerts a pull on the system. This is a typical track for October systems forming in the western Caribbean, as we can see from the historical track map shown in Figure 1. If this system does eventually affect the U.S., the most likely target would be the Florida Keys or the southwest coast of Florida. Historically, however, most storms forming in October in the western Caribbean miss the U.S. entirely, affecting just the Cayman Islands, Cuba, and the Bahamas. There is a chance that this trough would be too weak to recurve the system, and that instead it would continue west or drift southwest towards Honduras like Category 5 Hurricane Mitch did in October 1998.

Cape Verdes tropical disturbance
A tropical disturbance about 500 miles west of the Cape Verde Islands is experiencing high wind shear that will prohibit development for the next few days as it tracks west-northwest over the open ocean.

Katrina's winds revisited
In my last blog entry on this subject, we discussed the Florida Sun-Sentinel article commenting on new findings that indicate Katrina was only a Category 3 hurricane at first landfall near the mouth of the Mississippi, and a Category 1 hurricane over New Orleans. The article was rather imprecise in its use of the Category system for ranking hurricanes, and I interpreted the article to mean that Katrina was a Category 1 at landfall in Mississippi. Upon re-reading the article, I think what they were trying to say was that Katrina had Category 1 force winds over New Orleans, not that the storm itself was a Category 1. As several of you have pointed out, it is pretty difficult to have a hurricane with a 927 mb pressure (Katrina's pressure at landfall in Mississippi) with just Category 1 winds. Katrina was a least a strong Category 2, and perhaps a weak Category 3 hurricane at landfall in Mississippi. While Katrina did have unusualy high winds aloft compared to surface winds (which NHC noted on one of their discussions during the storm), this difference was not enough to make Katrina a Category 1 hurricane at landfall in Mississippi. Sorry for sowing the confusion!

My next post will be Sunday morning about 10 am.

Jeff Masters

No tropical depression yet near Jamaica

By: JeffMasters, 1:48 PM GMT on October 15, 2005

The broad 1005 mb low pressure area centered just south west of the island of Jamaica has become better organized this morning. The areal coverage of the deep convection continues to increase. Some weak upper-level outflow exists on the west and north sides of the system, and a weak upper level anti-cyclone has developed on top. Wind shear is still decreasing, and is now about 5 knots over the storm. All signs point to development of a tropical depression by Sunday, and a tropical storm by Monday. One complicating factor may be the presence of Jamaica so close to where the center is trying to form. This may slow development by half a day or so at most, since Jamaica is a relatively small island. A hurricane hunter aircraft is scheduled to investigate the system at 4 pm EDT today.

Global computer models forecast that the shear will continue to remain low the next several days over the western Caribbean, where the disturbance is expected to remain. If the system can remain in the western Caribbean for five days, the chances of it growing to hurricane strength are good. The latest GFDL model run even suggests that major hurricane status is possible.


Figure 1.
Early model tracks for the Jamaica disturbance.

Steering currents are expected to remain weak the next five days, and the computer models have a variety of solutions, so pick one:

GFS model: A weak tropical storm with a slow WSW motion, with landfall in Belize in seven days.

UKMET model: A hurricane with a slow WNW motion, winding up in the Yucatan Channel between Cuba and the Yucatan Peninsula in seven days.

NOGAPS model: Same as GFS, a weak tropical storm with a slow WSW motion, and a landfall in Belize in seven days.

GFDL model: A hurricane that moves WSW and stays in the Western Caribbean the next seven days.

Canadian model: Slow WSW motion as a tropical storm, then sharp northward turn and intensification into a hurricane as it crosses Cuba and passes just offshore Miami through the Bahama Islands.

If this system does eventually affect the U.S., the most likely target would be the Florida Keys or west coast of Florida, as there are many troughs of low pressure whizzing by that would grab this system and steer it to the northeast once it gets far enough north.

Cape Verdes tropical disturbance
A tropical disturbance about 500 miles west of the Cape Verde Islands is experiencing high wind shear that will prohibit development for the next few days as it tracks west-northwest over the open ocean.

Katrina's winds revisited
In my last blog entry on this subject, we discussed the Florida Sun-Sentinel article commenting on new findings that indicate Katrina was only a Category 3 hurricane at first landfall near the mouth of the Mississippi, and a Category 1 hurricane over New Orleans. The article was rather imprecise in its use of the Category system for ranking hurricanes, and I interpreted the article to mean that Katrina was a Category 1 at landfall in Mississippi. Upon re-reading the article, I think what they were trying to say was that Katrina had Category 1 force winds over New Orleans, not that the storm itself was a Category 1. As several of you have pointed out, it is pretty difficult to have a hurricane with a 927 mb pressure (Katrina's pressure at landfall in Mississippi) with just Category 1 winds. Katrina was a least a strong Category 2, and perhaps a weak Category 3 hurricane at landfall in Mississippi. While Katrina did have unusualy high winds aloft compared to surface winds (which NHC noted on one of their discussions during the storm), this difference was not enough to make Katrina a Category 1 hurricane at landfall in Mississippi. Sorry for sowing the confusion!

My next post will be Saturday afternoon about 5pm.

Jeff Masters

Jamaica system continues organizing

By: JeffMasters, 1:44 AM GMT on October 15, 2005

A broad 1005 mb low pressure area centered just south of the island of Jamaica continues to become better organized tonight. The areal coverage of the deep convection continues to increase, and a very impressive thunderstorm blow-up with very cold cloud tops has appeared just east of the island. Upper-level outflow has now appeared on the west and north sides of the system, and an upper level anti-cyclone has developed on top. Wind shear continues to drop, but more slowly than this afternoon, and is still in the 5 - 10 knot range. All these factors support continued development, and a tropical depression is likely to form here by Sunday. One complicating factor may be the presence of Jamaica so close to where the center is trying to form. This may slow development by half a day or so at most, since Jamaica is a relatively small island.

Global computer models forecast that the shear will continue to decrease over the area Saturday and Sunday, and the disturbance is expected to stay in the central or western Caribbean for at least the next five days, which would give ample time for this system to grow into a hurricane. The latest 18Z (2pm EDT) run of the GFS model is very unimpressed with this system, and keeps it a weak disturbance that gets swept up in a trough and pulled northeastward into the Bahamas. While this track is certainly possible, the GFS is probably underdoing the intensity. The environment this system is embedded in is very favorable for intensification into a hurricane. However, the 18Z run of the GFDL model is definitely overdone; it brings the system up to hurricane strength Saturday night, and then to a major hurricane by mid-week as it slowly tracks towards Honduras or Belize. While the GFDL is bringing this system to hurricane strength too fast, it does have the right idea about this potentially being a major hurricane. I believe that if this system stays in the western Caribbean for the next five days, the chances of it becoming a major hurricane are good. The GFDL had a very similar idea with Hurricane Rita--only it was too fast with its intensity forecast, and Rita ended up being a major hurricane three days after the GFDL originally forecasted this to happen.

It bears repeating that the eventual track of any tropical storm or hurricane that forms is impossible to forecast with any reliability, since steering currents are very weak and a some erratic motion is likely. The UKMET and NOGAPS models favor a track towards Honduras and Belize, while the GFS takes the system northeast across Cuba and the Bahamas. The early track models (i.e., BAM, LBAR and VICBAR models) have not been run yet for this system, but I will post them when they become available. If this system does eventually affect the U.S., the most likely target would be the Florida Keys or southwest Florida, as there are many troughs of low pressure whizzing by that would grab this system and steer it to the northeast once it got far enough north.

Cape Verdes tropical disturbance
A tropical disturbance about 500 miles southwest of the Cape Verde Islands continues to have some potential for slow development as it tracks west-northwest over the open ocean.

New England
New England continues to suffer the onslaught of a very wet stream of tropical air from the southeast that has caused nine straight days of rain. The axis of moisture has shifted slightly eastwards today, finally giving New York City a break from the 6 - 8 inches of rain that has fallen the past two days alone. This tropical onslaught will continue moving northeast over the weekend before exiting northern Maine on Sunday.


Figure 2. Lots of rain in the Northeast the past week, but currently just a few areas of major river flooding, in New Jersey.

Katrina's winds revisited
In my last blog entry on this subject, we discussed the Florida Sun-Sentinel article commenting on new findings that indicate Katrina was only a Category 3 hurricane at first landfall near the mouth of the Mississippi, and a Category 1 hurricane over New Orleans. The article was rather imprecise in its use of the Category system for ranking hurricanes, and I interpreted the article to mean that Katrina was a Category 1 at landfall in Mississippi. Upon re-reading the article, I think what they were trying to say was that Katrina had Category 1 force winds over New Orleans, not that the storm itself was a Category 1. As several of you have pointed out, it is pretty difficult to have a hurricane with a 927 mb pressure (Katrina's pressure at landfall in Mississippi) with just Category 1 winds. Katrina was a least a strong Category 2, and perhaps a weak Category 3 hurricane at landfall in Mississippi. While Katrina did have unusualy high winds aloft compared to surface winds (which NHC noted on one of their discussions during the storm), this difference was not enough to make Katrina a Category 1 hurricane at landfall in Mississippi. Sorry for sowing the confusion!

My next post will be Saturday morning about 11am.

Jeff Masters

Jamaica disturbance getting better organized

By: JeffMasters, 8:38 PM GMT on October 14, 2005

A broad 1005 mb low pressure area centered over the island of Jamaica continues to become better organized. There has been an increase in intensity and areal coverage of the deep convection this afternoon, and some upper-level cirrus clouds moving northwards away from the storm show the beginnings of what may be an upper-level outflow channel starting to develop. An upper level anti-cyclone is beginning to develop on top, and the wind shear continues to drop--down to 5 - 10 knots. This low enough to support continued organization. The presence of Jamaica so close to where the center is trying to form will probably not pose a significant problem for the storm, since Jamaica is a relatively small island.

Global computer models forecast that the shear will continue to decrease over the area Saturday and Sunday, and I believe that a tropical depression is likely by Saturday or Sunday. Steering currents are very weak, and the disturbance is expected to stay in the central or western Caribbean for at least the next five days, which would give ample time for this system to grow into a hurricane.

It bears repeating that the eventual track of any tropical storm or hurricane that forms is impossible to forecast with any reliability, since steering currents are very weak and a some erratic motion is likely. The UKMET and NOGAPS models favor a track towards Honduras and Belize, while the GFS takes the system northeast across Cuba and the Bahamas. The early track models (i.e., BAM, LBAR and VICBAR models) have not been run yet for this system, but I will post them when they become available.

Cape Verdes tropical disturbance
A tropical disturbance about 500 miles southwest of the Cape Verde Islands continues to slowly improve in organization. Visibile satellite imagery and QuikSCAT satellite winds suggest that a surface circulation may be forming here, and some modest upper-level outflow has developed to the north. The system is headed towards an area of low wind shear, which may allow some further development over the next few days as it tracks west-northwest over the open ocean. Tropical storms developing this far east in mid-October are very rarely a threat to the Caribbean or North America.

New England
New England continues to suffer the onslaught of a very wet stream of tropical air from the southeast that has caused nine straight days of rain. The axis of moisture has shifted slightly eastwards today, finally giving New York City a break from the 6 - 8 inches of rain that has fallen the past two days alone. This tropical onslaught will continue moving northeast over the weekend before exiting northern Maine on Sunday.


Figure 2. Lots of rain in the Northeast the past week, but currently just a few areas of major river flooding, in New Jersey.

Katrina's winds revisited
In my last blog entry on this subject, we discussed the Florida Sun-Sentinel article commenting on new findings that indicate Katrina was only a Category 3 hurricane at first landfall near the mouth of the Mississippi, and a Category 1 hurricane over New Orleans. The article was rather imprecise in its use of the Category system for ranking hurricanes, and I interpreted the article to mean that Katrina was a Category 1 at landfall in Mississippi. Upon re-reading the article, I think what they were trying to say was that Katrina had Category 1 force winds over New Orleans, not that the storm itself was a Category 1. As several of you have pointed out, it is pretty difficult to have a hurricane with a 927 mb pressure (Katrina's pressure at landfall in Mississippi) with just Category 1 winds. Katrina was a least a strong Category 2, and perhaps a weak Category 3 hurricane at landfall in Mississippi. While Katrina did have unusualy high winds aloft compared to surface winds (which NHC noted on one of their discussions during the storm), this difference was not enough to make Katrina a Category 1 hurricane at landfall in Mississippi. Sorry for sowing the confusion!

I'll have an update tonight by 10pm if the Jamaica system continues to develop. I'll post my follow-up to the Katrina winds posting I made yesterday when I get it done. This is a complicated subject, and it's taking me a long time to do the write-up, sorry for the delay!

Jeff Masters

Eye on Jamaica

By: JeffMasters, 2:08 PM GMT on October 14, 2005

A broad 1006 mb low pressure area is centered just south of Jamaica this morning, and is a definite threat to develop into a tropical depression over the next few days. Some impressive thunderstorms have developed to the south of Jamaica this morning, and the general organization of this system has improved since yesterday. This is largely due to the fact that wind shear overhead has dropped from 15 knots yesterday to 10 knots today. No upper level outflow or low-level spiral banding is apparent on satellite imagery yet.

Global computer models forecast that the shear will continue to decrease over the area Saturday and Sunday, and I think it is 70% likely by Monday that a tropical depression will form. Steering currents are very weak, and the disturbance is expected to stay in the central or western Caribbean for at least the next five days. This is a set-up typical of what we've seen in the past for the formation of late-October hurricanes. It would be no surprise if this system ended up becoming a hurricane five to seven days from now. Water temperatures are still very high--up to 32 C near Jamaica--so the ocean can even support a major hurricane, although this is rare in late October.

The eventual track of any tropical storm or hurricane that forms is impossible to forecast with any reliability, since steering currents are very weak and a some erratic motion is likely. The various computer models either keep the storm in the Caribbean the next seven days, or move it northeast across Cuba and the Bahamas, or move it west or southwest across Central America or Mexico's Yucatan. In other words, anything can happen.


Figure 1. Current Sea Surface Temperatures compiled by NOAA's AOML.

Cape Verdes tropical disturbance
A tropical disturbance about 500 miles southwest of the Cape Verde Islands continues to slowly improve in organization. Visibile satellite imagery and QuikSCAT satellite winds suggest that a surface circulation may be forming here, and some modest upper-level outflow has developed to the north. The system is headed towards an area of low wind shear, which may allow some further development over the next few days as it tracks west-northwest over the open ocean. Tropical storms developing this far east in mid-October are very rarely a threat to the Caribbean or North America.

New England
New England continues to suffer the onslaught of a very wet stream of tropical air from the southeast that has caused nine straight days of rain. The axis of moisture has shifted slightly eastwards today, finally giving New York City a break from the 6 - 8 inches of rain that has fallen the past two days alone. This tropical onslaught will continue moving northeast over the weekend before exiting northern Maine on Sunday.


Figure 2. Lots of rain in the Northeast the past week, but currently just a few areas of major river flooding, in New Jersey.

I'll have an update this afternoon around 3pm, and follow-up then on my post yesterday about Katrina's winds.

Jeff Masters

Time to watch the Western Caribbean

By: JeffMasters, 10:37 PM GMT on October 13, 2005


The large upper level low pressure system that has been anchored over the ocean between Bermuda and Puerto Rico the past week has finally begun to lift northwards. As a result, the amount of wind shear over the western Caribbean has begun to drop today, resulting in an increase in thunderstorm activity over a weak low pressure area centered 150 miles southeast of Jamaica. However, there is no edivence of any upper-level outflow setting up, or any low-level spiral banding. The wind shear over the disurbance is still a rather high 10 - 20 knots, which should prevent any tropical development through Friday. However, the global computer models are forecasting this shear to drop below 10 knots by Saturday, which could allow a tropical depression to develop. Now that it is mid-October, the western Caribbean is the primary area we need to be concerned about for tropical storm development. Water temperatures are still very high there, up to 32 C near Jamaica. Historically, the worst hurricanes to form in the last half of October have all been western Caribbean hurricanes.

Any development that occurs this weekend would appear to primarily be a threat to Honduras and Nicaragua, according to the UKMET, NOGAPS, and GFS models. Let's hope the atmosphere is not setting up for a repeat of 1998's Hurricane Mitch, which formed in the western Caribbean in late October and hit Honduras as a Category 5 hurricane, killing over 10,000.


Figure 1. Current Sea Surface Temperatures compiled by NOAA's AOML.

Cape Verdes tropical disturbance
A concentrated are of thunderstorms has developed about 450 miles southwest of the Cape Verdes Islands this afternoon. While there is no surface circulation apparent on satellite imagery yet, some modest upper-level outflow has developed to the north, and the system is headed towards an area of low wind shear. Some further development of this system is possible over the next few days as it tracks west-northwest over the open ocean. Tropical storms devloping this far east in mid-October are never a threat to the Caribbean or North America; only the Azores Islands needs to be concerned about development in this region.

New England
New England, and particularly the New York City region, continues to get soaked by an endless stream of tropical moisture. Several small low pressure areas have formed along the axis of disturbed weather stretching from New York southeastwards towards Bermuda, but wind shear is too high and water temperatures too marginal for any significant tropical development to occur in this region. The axis of the line of disurbed weather is forecast to move slowly northeast in to Maine this weekend, finally bringing an end to the rains.

Jeff Masters

Katrina only a Cat 1 in New Orleans?

By: JeffMasters, 1:50 PM GMT on October 13, 2005


Eye of Hurricane Katrina at sunset on August 28, 2005, when Katrina was at peak intensity. Photo credit: Deanna Hence. The photo was taken on NOAA hurricane hunter aircraft N43RF, which was participating in the Hurricane Rainband and Intensity Change Experiment, RAINEX, aimed to study the interaction between a hurricane's eyewall and the rainbands located outside the eyewall region, and how these changes affect hurricane intensity.

Was Katrina much weaker at landfall than originally thought? That's what analysis of the Katrina's wind data by Dr. Mark Powell of NOAA's Hurricane Research Division is showing. Dr. Powell is the world's expert on windspeeds measured in landfalling hurricanes, so his findings are being carefully studied by the National Hurricane Center (NHC) as they prepare their final report on Katrina. The NHC advisories had Katrina as a Category 4 hurricane with sustained winds of 145 mph when it struck the Louisiana coast near Buras, and a Category 3 hurricane with 125 winds when it passed 35 miles east of New Orleans. But Dr. Powell's analysis suggests that Katrina was a Category 3 hurricane with 115 mph winds at first landfall, and that the strongest winds that affected New Orleans were 95 mph. The analysis was done using data sources that were unavailable to the NHC in real time, including surface anemometers as well as Doppler radar measurements of wind speed from NOAA's hurricane hunter aircraft. While the results are still considered preliminary, I believe that when the official National Hurricane Center report on Katrina comes out in early 2006, Katrina will be "demoted" to a Category 3 hurricane. The full story was printed by the Florida Sun-Sentinel.

Many of the new ground based wind measurements were published on the New Orleans National Weather Service web site on Friday, October 7, in their post-storm report on Katrina. The highest sustained winds measured at any ground-based site were 90 mph on Lake Pontchartrain. The highest gust measured on the ground was 135 mph in Poplarville, MS. Many wind measurement sites failed during the storm, so we will have to rely on aircraft and Doppler radar to arrive at the true wind speeds of Katrina at landfall. Here's a few highlights of the highest winds measured at the ground during Katrina, before instrument failure:

New Orleans Lakefront Airport: sustained winds of 69 mph, gusting to 86 mph.
Biloxi's Keesler Air Force Base: sustained winds of 54 mph, gusting to 90 mph.
Gulfport airport: 46 mph, gusting to 58 mph.
Lake Ponchartrain mid-lake buoy: 90 mph, gusting to 114 mph.

Many of us heard that Category 5 winds were measured by the National Weather Service in Katrina. These rumors were aired as fact by television stations and other media outlets during the storm. However, as the post-storm report above outlines, these were just rumors, and no such winds were measured. If you listened to NPR last night, you also might have heard the story of how television stations in Baton Rouge were reporting a huge crime wave in Baton Rouge after the hurricane, and that an armed gang had even taken over the Mayor's office. These reports, later found out to be completely untrue, led to four-hour waits to buy guns at local gun stores in Baton Rouge. According to NPR, there was no increase in crime in Baton Rouge after the hurricane. The media, at times, did a poor job in separting fact from fiction during the storm, and there were in reality no sustatined winds above Category 1 measured on the ground during Katrina.

Obviously, a demotion of Katrina to Category 3 status would have political consequences. The levees of New Orleans were supposed to be able to withstand a Category 4 hurricane, and it appears as if they were done in by winds of only 95 mph--what one would find in a strong Category 1 hurricane. Still, Katrina at landfall in Mississippi was no ordinary hurricane. It brought the largest storm surge ever recorded in an Atlantic Hurricane to shore in Mississippi--28 feet, measured at the Hancock County, Mississippi EOC in Bay St. Louis. This is over five feet higher than the previous record set in Category 5 Hurricane Camille of 1969. So while the winds at landfall in Mississippi may have been Category 3 or even lower, the storm surge was a Category 5 plus! The storm surge levels that breached the New Orleans levees were probably characteristic of at least a Category 3 hurricane, and perhaps a Category 4. As both myself and Steve Gregory have emphasized in our blogs, the Saffir-Simpson scale of ranking hurricanes is inadequate; an additional scale ranking storms by damage potential from winds, storm surge and rainfall is needed. The reason no such scale has been implemented yet is that the NHC fears the added complexity may serve only to confuse the public. This is a valid concern, considering 40% of New Orleans' population before Katrina was illiterate, making hurricane education a very difficult undertaking in this city. Add to this the fact that many areas of the booming U.S. coast are being populated by hurricane neophytes, who just moved to the coast from areas that don't have hurricanes. Perhaps now that Katrina has gotten our attention, though, hurricane education will be an easier task, and we can start the talk about implementing a new damage scale.

Jeff Masters

Disturbed weather from Bermuda to Honduras

By: JeffMasters, 1:57 PM GMT on October 12, 2005

An unusually large and long-lasting area of low pressure with heavy rains continues to affect a large section of ocean from New England to Bermuda south to Puerto Rico, and then westward across Hispanolia and Jamaica to Honduras. Over 10 inches of rain has fallen over much of Puerto Rico the past two days. The entire island is under a flash flood warning today, and many rivers are out of their banks and many streets and neighborhoods flooded.

Wind shear levels over this disturbed area are in the 10 - 20 knot range, which is too high to allow much in the way of tropical storm development to occur. The various global computer models continue to insist that a tropical storm will develop this week between Puerto Rico and Bermuda and move north to threaten Bermuda, but thus far the models have performed very poorly with their predictions of tropical cyclone development with this weather pattern. If development does occur, it would likely be focused on one of two low level circulations that have developed, one just north of Jamaica near 19N75W and another midway between Puerto Rico and Bermuda near 25N67W.

Stan's toll
I will continue to talk about Stan's destruction for a while yet. This is a disaster that has killed many more people and caused more suffering than Hurricane Katrina, yet will not get nearly the attention it deserves because of the earthquake in Pakistan.

Today the death toll in Guatemala stands at 1252. Another 133 people died in El Salvador, Mexico, Costa Rica, Nicaragua and Honduras. Many more lie buried in areas rescuers still cannot reach, although by today 95% of the affected communities had been. Particularly hard hit were the coastal mountains of Guatemala near the Mexican border. Some of our wunderground members have sent in some remarkable photos of the floods in Guatemala, a few of which I link to below.

The next update will be Thursday morning, unless some unexpected development happens. I will talk about some new estimates of what Katrina's winds really were at landfall, and the results are surprising.

Jeff Masters

Vince: Spain's first tropical cyclone

By: JeffMasters, 1:44 PM GMT on October 11, 2005

Tropical Storm Vince made history today as the first tropical cyclone ever recorded to hit Spain. Vince scooted just south of Portugal and came ashore on the southwest Spanish coast opposite Sevilla. Vince made landfall as a tropical depression with 35 mph sustained winds and a central pressure of 1002 mb. Heavy rains and sustained winds of 31 mph with winds gusts of 48 mph were measured at Rota, Spain today, and winds of 36 mph gusting to 51 mph were measured at Jerez de la Frontera, Spain. Vince is no longer a tropical cyclone, and is not expected to cause damage in Spain. In fact, since Spain and Portugal are suffering their worst drought in 120 years, Vince will bring welcome rains to many areas.


Figure 1. Hurricane Vince at landfall. Image credit: Navy Research Lab, Monterey, CA.

The only other tropical cyclone I could find record of to hit Europe was Hurricane Debbie, which hit northwest Ireland on September 16, 1961 as a Category 1 hurricane. Wind gusts as high as 113 mph were measured in the storm at Malin Head, the northernmost point in Ireland. Debbies's winds caused widespread destruction in Ireland's County Denegal.

Puerto Rico disturbance
A large area of disturbed weather extends from Bermuda southwards to Puerto Rico and then westward across much of the Caribbean Sea. Wind shear levels in the disturbed area are about 20 knots--too high for tropical storm develoment today. This wind shear may relax over the next few days, possibly allowing some developement to occur. Most of the global computer models continue to predict that a tropical storm will form from this disturbed area later this week and move north to threaten Bermuda. However, the models are being less aggressive with this development than in previous runs, and in general, the tropics are looking much less conducive for tropical storm formation than a week ago.


Figure 2. Current radar precipiation estimates out of Puerto Rico show heavy rains from a tropical disturbance have affected most of the island.

Stan
Improving weather has let rescuers reach many of the hardest-hit areas of Guatemala flooded by Hurricane Stan's rains last week. A new mudslide in the west part of the country buried up to 40 more vicitms Monday, and many hundreds more remain missing and presumed buried throughout the country.

Northeast U.S. flooding
The remains of Tropical Storm Tammy cause extensive flooding in New England and the mid Atlantic the past two days, killing at least ten and bringing New Hampshire its worst flooding in a least 25 years. With additional rain beginning tonight and extending through Thursday, New England can expect continued flooding problems this week. New rain amounts may be as high as 2 - 3 inches in some areas.


Figure 3. Radar estimates of rainfall in New Engalnd from the remains of Tropical Storm Tammy.

Jeff Masters

Flood

No new news on Vince or Puerto Rico disturbance

By: JeffMasters, 8:36 PM GMT on October 10, 2005

The low pressure area that formed near Puerto Rico this morning is now north of the island. No increase in organization has happened today, and wind shear remains high enough--20 knots--that no development can occur until Tuesday at the earliest. The low continues to bring heavy rain to Puerto Rico and the surrounding islands. Most of the global computer models continue to predict that a tropical storm will form from this disturbed area of weather later this week and move north to threaten Bermuda.


Figure 2. Current radar out of Puerto Rico shows some banding developing in association with a low to the north of the island.

Vince
Vince is headed east towards Portugal, and is still holding together in the face of 22 C water temperatures and 30 knots of wind shear. The cold water and wind shear will destroy Vince by tomorrow, before he can hit land. Vince recently passed over a buoy that measured a central pressure of 996.7 mb. Vince's remains will bring heavy rain and 30 mph winds to southern Portugal on Tuesday.


Figure 1. Hurricane Vince at peak strength, Sunday October 9, 17 GMT. Image credit: Navy Research Lab, Monterey, CA.

Stan
There is no new news on Stan's death toll today, which remains in the 1000 - 2000 range. Most of these deaths occurred in the Lake Atitlan area.

For those of you who want to help out, wunderground member neavilag in Guatemala recommends a donation to the Guatemalan Red Cross:

Intermediary Bank
CITIBANK
399 PARK AVENUE, NEW YORK N.Y. 10043
U.S.A.
ABA 021000089
SWIFT CITIUS33

Paying institution:
Banco del Cafe, S. A. Guatemala
Account 36009832
swift CAFBGTGC

For final credit to:
Cruz Roja Guatemalteca Acct Number 81-03-44361-0

My next update will be Tuesday at 9:30 am EDT.

Jeff Masters

Oddball Vince; new Puerto Rico development

By: JeffMasters, 1:41 PM GMT on October 10, 2005

Vince is definitely an oddball storm. First of all, it's ridiculous that we're up to a "V" storm in early October. Second of all, Vince formed in a very unusual location--off the coast of Portugal. No known tropical storm has ever formed so far north and east. Thirdly, Vince formed in a region where water temperatures were only about 24 C--usually, 26 C is needed! Fourthly, Vince is incredibly tiny--and was a hurricane for about 12 hours!



Vince is in a strange location, but not unprecedented. Vince is pretty far east--16.6 West longitude at the 5am EDT advisory--but there have been hurricanes that have been even further east than Vince. For example, in 1965, Hurricane Carol made it to 16 West near the coast of Portugal before being downgraded from a tropical storm to a tropical depression. And in 1961, Hurricane Debbie hit Ireland as a Category 1 hurricane, passing longitude 8 West before losing hurricane characteristics. So, Vince's location isn't unprecedented. But this sure is a weird exclamation mark to put on the end of a once-in-a-lifetime hurricane season!

Vince won't be with us for long, and is already starting to rapidly decay. He's over cold 23C waters now, and wind shear from the northwest has blown away all the convection on that side, exposing the low-level center. A cold front approaching Europe will pick up Vince Tuesday morning, and finish tearing Vince apart. Vince's remains should bring Portugal and Spain heavy rains and winds gusts to 45 mph on Tuesday. Portugal gets the remains of tropical storms every 5 - 10 years, on average. This occurred most recently in October 1998 with Jeanne.

New development near Puerto Rico
A strong upper-level low north of Puerto Rico is creating a large curved band of disturbed weather from the Bahamas through the central Caribbean to the Leeward Islands. A surface low pressure area has developed just south of Puerto Rico this morning in association with this area, and has rotated northeastward to the east side of Puerto Rico. Some spiral banding has developed to the southeast of this low, and this low will have to be watched for signs it is turning into a tropical depression. This morning, sustained winds of 27 mph, gusting to 33 mph, were observed at St. Thomas in the Virgin Islands. Although wind shear is too high today to support a tropical depression developing in this area, most of the global computer models predict that a tropical storm will form from this disturbed area of weather later this week and move north to threaten Bermuda.


Figure 2. Current radar out of Puerto Rico shows some spiral banding developing in association with a low to the east of the island.

The tropical disturbance we've been following about 300 miles east of the Lesser Antilles Islands remains disorganized, and is not expected to develop in the next two days.

Stan
There is no new news on Stan's death toll today, which remains in the 1000 - 2000 range. Most of these deaths occurred in the Lake Atitlan area (see wunderphoto below). Stan now ranks as one of the 30 most deadly hurricanes of all time.

For those of you who want to help out, I suggest a donation to the Guatemalan Red Cross:

Intermediary Bank
CITIBANK
399 PARK AVENUE, NEW YORK N.Y. 10043
U.S.A.
ABA 021000089
SWIFT CITIUS33

Paying institution:
Banco del Cafe, S. A. Guatemala
Account 36009832
swift CAFBGTGC

For final credit to:
Cruz Roja Guatemalteca Acct Number 81-03-44361-0

The next update will be Monday by 4 pm, or earlier if the Puerto Rico low develops.

Jeff Masters

Huh? Hurricane Vince????

By: JeffMasters, 1:59 AM GMT on October 10, 2005

OK, this is definitely a weird storm. First of all, it's ridiculous that we're up to a "V" storm in early October. Second of all, Vince formed in a very unusual location--off the coast of Portugal--and in a region where water temperatures are only about 24 C. No tropical storm has ever formed so far north and east. Thirdly, Vince is incredibly tiny--and now a hurricane! I know I always harp on the rule that a water temperature of at least 26C is needed for tropical storm formation to occur, but we can bend that rule a little when a tropical storm forms from a pre-existing non-tropical low pressure system that sits over water for many days, and gradually acquires a warm core. As we've already seen, the Hurricane Season of 2005 doesn't care much about what is usual. The storm was too far east to fit on our newer tracking maps, so I dusted off some European maps for the purpose.



Vince is in a strange location, but not unprecedented. Vince is pretty far east--18.6 West longitude at the 5pm EDT advisory--but there have been hurricanes that have been even further east than Vince. For example, in 1965, Hurricane Carol made it to 17.8 West near the coast of Portugal before being downgraded from a hurricane to a tropical storm. And in 1961, Hurricane Debbie hit Ireland as a Category 1 hurricane, passing longitude 8 West before losing hurricane characteristics (sorry my maps don't extend all the way to Europe, I'm going to have to fix this). So, Vince's location isn't unprecedented, and you can't blame Vince on global warming, given that Vince is forming in such cold waters! But this sure is a weird exclamation mark to put on the end of a once-in-a-lifetime hurricane season.

The rest of my discussion from this morning appears below, unchanged.

Vince won't be with us for long. A cold front approaching Europe will pick up Vince Tuesday morning, and cold water and wind shear will tear Vince apart. Vince's remains should bring Portugal and Spain heavy rains and winds gusts to 45 mph on Tuesday. Portugal gets the remains of tropical storms every 5 - 10 years, on average. This occurred most recently in October 1998 with Jeanne.

Subtropical Depression 22
Subtropical Depression 22 dissipated Saturday evening, torn apart by wind shear. Its remnants will continue west towards the Carolinas, but are not expected to regenerate or bring significant rains to the U.S., as the wind shear is too high (30 knots) for re-development to occur.

What's behind TD 22?
The tropical disturbance we've been following near 15N 53W, about 450 miles east of the Lesser Antilles Islands, has a low level circulation, but the cloud pattern is disorganized. Development is not expected today or Monday, but some slow development after that is possible.

A strong upper-level low north of Puerto Rico is creating a large curved band of disturbed weather from the Bahamas through the central Caribbean to the Leeward Islands. No development is likely in this area until Tuesday, when the low is expected to weaken and move north and reduce the amount of wind shear over the area. Several of the computer models predict that a tropical storm could form from this disturbed area of weather by mid-week and move north to threaten Bermuda.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

Stan
There is no new news on Stan's death toll today, which remains at about 1500. Stan now ranks as one of the 30 most deadly hurricanes of all time. Stan now surpasses Katrina as the most deadly hurricane of 2005; Katrina's death toll stood at 1242 at last count, with 1003 of the deaths in Louisiana.


Figure 2.Total precipition for the year (PC = precipitation in incehs) from a station in Guatemala. During a 5-day period of rain from Stan, this station picked up 17 inches of rain.

The grim task of recovering bodies in Guatemala continues today, where the entire town of Panabaj in western Guatemala was buried in a landslide, killing all 800 residents. The entire village may be declared a mass grave, as rescuers move on to find victims of more survivable mudslides. Another 600 died in mudslides elsewhere in Guatemala. The storm also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua. Hundreds more are missing and presumed buried under landslides near Lake Atitlan in Guatemala.

The next update will be Monday around 10 am.

Jeff Masters

Vince: a first

By: JeffMasters, 3:41 PM GMT on October 09, 2005

Tropical Storm Vince
Tropical Storm Vince's formation today marks the first time that a storm beginning with the letter "V" has been given name. With 20 named storms, the Hurricane Season of 2005 is now in sole possession of second place on the list of busiest hurricane seasons of all time. Only 1933, with 21 storms, had more (back before they started naming storms). Vince formed in a very unusual location, not far from the coast of Spain, and in a region where water temperatures are only 23 - 24 C. I know I always harp on the rule that a water temperature of at least 26C is needed for tropical storm formation to occur, but we can bend that rule a little when a tropical storm forms from a pre-existing non-tropical low pressure system that sits over water for many days, and gradually acquires a warm core. As we've already seen, the Hurricane Season of 2005 doesn't care much about what is usual, and Vince's formation is certainly ample evidence of that. The storm was too far east to fit on our newer tracking maps, and just barely appears on one of our old tracking charts I had to dust off this morning, special for the occasion!

Vince won't be with us for long. A cold front approaching Europe will pick up Vince Tuesday morning, and cold water and wind shear will tear Vince apart. Vince's remains should bring Portugal and Spain heavy rains and winds gusts to 45 mph on Tuesday. Portugal gets the remains of tropical storms every 5 - 10 years, on average. This occurred most recently in October 1998 with Jeanne.

Subtropical Depression 22
Subtropical Depression 22 dissipated Saturday evening, torn apart by wind shear. Its remnants will continue west towards the Carolinas, but are not expected to regenerate or bring significant rains to the U.S., as the wind shear is too high (30 knots) for re-development to occur.

What's behind TD 22?
The tropical disturbance we've been following near 15N 53W, about 450 miles east of the Lesser Antilles Islands, has a low level circulation, but the cloud pattern is disorganized. Development is not expected today or Monday, but some slow development after that is possible.

A strong upper-level low north of Puerto Rico is creating a large curved band of disturbed weather from the Bahamas through the central Caribbean to the Leeward Islands. No development is likely in this area until Tuesday, when the low is expected to weaken and move north and reduce the amount of wind shear over the area. Several of the computer models predict that a tropical storm could form from this disturbed area of weather by mid-week and move north to threaten Bermuda.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

Stan
There is no new news on Stan's death toll today, which remains at about 1500. Stan now ranks as one of the 30 most deadly hurricanes of all time. Stan now surpasses Katrina as the most deadly hurricane of 2005; Katrina's death toll stood at 1242 at last count, with 1003 of the deaths in Louisiana.


Figure 2.Total precipition for the year (PC = precipitation in incehs) from a station in Guatemala. During a 5-day period of rain from Stan, this station picked up 17 inches of rain.

The grim task of recovering bodies in Guatemala continues today, where the entire town of Panabaj in western Guatemala was buried in a landslide, killing all 800 residents. The entire village may be declared a mass grave, as rescuers move on to find victims of more survivable mudslides. Another 600 died in mudslides elsewhere in Guatemala. The storm also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua. Hundreds more are missing and presumed buried under landslides near Lake Atitlan in Guatemala.

The next update will be Monday around 10 am.

Jeff Masters

TD 22 dies

By: JeffMasters, 3:03 AM GMT on October 09, 2005

Subtropical Depression 22
Subtropical Depression 22 dissipated Saturday evening, torn apart by wind shear. Its remnants will continue west towards the Carolinas, but are not expected to regenerate or bring significant rains to the U.S.

What's behind TD 22?
The tropical disturbance we've been following about 650 miles east of the Lesser Antilles Islands has grown disorganized, and now has 20 knots of shear over it. Development is not expected on Sunday, but some slow development after that is possible.

Deep convection has increased at the center of a non-tropical low between the Canary Islands and the Azores Islands. This low may become a subtropical depression on Sunday or Monday. Little motion is expected the next two days.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

Stan
Stan now ranks as one of the 30 most deadly hurricanes of all time, with over 1500 deaths caused. Stan will proabably far surpass Katrina as the most deadly hurricane of 2005; Katrina's death toll stood at 1242 at last count, with 1003 of the deaths in Louisiana. The grim task of recovering bodies in Guatemala continues today, where the entire town of Panabaj in western Guatemala was buried in a landslide, killing all 800 residents. Another 600 died in mudslides elsewhere in Guatemala. The storm also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua. Hundreds more are missing and presumed buried under landslides near Lake Atitlan in Guatemala. In a freakish double whammy, a magnitude 5.8 earthquake hit Guatemala Friday, causing additional damage, but no deaths. Also bizzare is the volcanic eruption that occured during the height of Stan rains in El Salvador on October 1. The eruption killed two and injured dozens. When you add these events to the magnitude 5.4 earthquake that rocked Taiwan at the height of Tyhoon Longwang on October 1, one might wonder if there is a connection between seismic activity and hurricane activity! There isn't.

October outlook
Historically, 20% of all Atlantic tropical storms have occured in the month of October. In a nomal year, this means we can expect two tropical storms, one of which becomes a hurricane. According to Dr. Bill Gray's October 2005 hurricane forecast issued on October 3, this year we can expect an above average October, with three tropical storms, two of which become hurricanes--one of those a major hurricane. We have already had two named storms this month, Stan and Tammy. Long range computer model forecasts continue to show that conditions for breeding tropical storms will be excellent until at least the last week of October, so two more named storms--Vince and Wilma--will likely result by the end of October. This would tie 2005 with 1933 as the busiest hurricane season ever. It is interesting to note that in 1933, the final three storms all showed up after October 25. If 2005 follows a similar pattern, we'll have Alpha, and Beta in addition to Vince and Wilma before it's all over. Dr. Bill Gray is not forecasting any November storms to form. However, we should get at least one, given the current pattern and continued above-normal sea surface temperatures over the Atlantic.


Figure 2. Typical tropical storm formation areas for October.

The next update will be Sunday around 11 am.

Jeff Masters

Stan one of the 30 most deadly hurricanes; TD 22 continues WNW

By: JeffMasters, 9:45 PM GMT on October 08, 2005

Stan
Stan now ranks as one of the 30 most deadly hurricanes of all time, with over 1500 deaths caused. Stan will proabably far surpass Katrina as the most deadly hurricane of 2005; Katrina's death toll stood at 1242 at last count, with 1003 of the deaths in Louisiana. The grim task of recovering bodies in Guatemala continues today, where the entire town of Panabaj in western Guatemala was buried in a landslide, killing all 800 residents. Another 600 died in mudslides elsewhere in Guatemala. The storm also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua. Hundreds more are missing and presumed buried under landslides near Lake Atitlan in Guatemala. In a freakish double whammy, a magnitude 5.8 earthquake hit Guatemala Friday, causing additional damage, but no deaths. Also bizzare is the volcanic eruption that occured during the height of Stan rains in El Salvador on October 1. The eruption killed two and injured dozens. When you add these events to the magnitude 5.4 earthquake that rocked Taiwan at the height of Tyhoon Longwang on October 1, one might wonder if there is a connection between seismic activity and hurricane activity! There isn't.

Subtropical Depression 22
Subtropical Depression 22, located about 300 miles southeast of Bermuda this evening, is not entirely tropical in nature. There are some substantial horizontal changes in temperature like one finds in regular mid-latitude low pressure systems, and the maximum winds are found in a curved band to the storm's northeast, well away from the center. Storms of this nature are called subtropical. If this system continues to intensify and attain maximum sustained winds of 40 mph, it wil be named Subtropical Storm Vince. See the Hurricane FAQ for more information on subtropical storms.

Wind shear over the system is about 15 knots this evening, which is barely favorable for tropical storm development. Wind shear is expected to fluctuate around 10-15 knots through Monday, which should allow some slow intensification. After that time, higher shear is expected. TD 22 is over water of 26 - 27C, which is just warm enough to support a tropical storm. However, its current track will push the storm just south of Bermuda on Sunday, where water temperatures fall below 26C, which may cause some temporary weakening before the waters warm up again. By Tuesday, when the storm is expected to turn north, water temperatures again fall below 26C, and slow weakening should result. However, the forecast beyond three days has a higher than usual level of uncertainty, because most of the computer models are forecasting that a second tropical cyclone may form behind TD 22 by Monday and steer the storm more to the west. In any case, intensification beyond a strong tropical storm is unlikely given the marginal sea surface temperatures and wind shear, and the worst the U.S. is likely to get from this storm is a repeat of Tropical Storm Tammy.


Figure 1.Sea Surface temperatures below TD 22 are just barely high enough to support a tropical storm. The blue color (26C) is the dividing line between temperatures that are warm enough and not warm enough to support a tropical storm.

What's behind TD 22?
The tropical disturbance we've been following about 650 miles east of the Lesser Antilles Islands has grown disorganized today, and now has 20 knots of shear over it. Development is not expected through Sunday of this system.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

October outlook
Historically, 20% of all Atlantic tropical storms have occured in the month of October. In a nomal year, this means we can expect two tropical storms, one of which becomes a hurricane. According to Dr. Bill Gray's October 2005 hurricane forecast issued on October 3, this year we can expect an above average October, with three tropical storms, two of which become hurricanes--one of those a major hurricane. We have already had two named storms this month, Stan and Tammy. Vince seems like a good bet by Sunday. Long range computer model forecasts continue to show that conditions for breeding tropical storms will be excellent until at least the last week of October, so two more named storms--Vince and Wilma--will likely result by October 21. This would tie 2005 with 1933 as the busiest hurricane season ever. It is interesting to note that in 1933, the final three storms all showed up after October 25. If 2005 follows a similar pattern, we'll have Alpha, Beta and Gamma in addition to Vince and Wilma before it's all over. Dr. Bill Gray is not forecasting any November storms to form. However, we should get at least one, given the current pattern and continued above-normal sea surface temperatures over the Atlantic.


Figure 2. Typical tropical storm formation areas for October.

The next update will be Sunday around 11 am.

Jeff Masters

Subtropical Depression 22; Stan's death toll 1500 and rising

By: JeffMasters, 3:45 PM GMT on October 08, 2005

Subtropical Tropical Depression 22 formed from a non-tropical low 300 miles southeast of Bermuda. This low is not entirely tropical in nature--there are some substantial horizontal changes in temperature like one finds in regular mid-latitude low pressure systems, and the maximum winds are found in a curved band to the storm's northeast, well away from the center. Storms of this nature are called subtropical. If this system continues to intensify and attain maximum sustained winds of 40 mph, it wil be named Subtropical Storm Vince. See the Hurricane FAQ for more information on subtropical storms.

Wind shear over the system is about 10 knots today, which is slightly favorable for tropical storm development. However, in the noon to 1 pm EDT time frame, wind shear from the southeast increased and blew the deep convection away from the center, which was exposed. The center re-formed to the northwest under the deepest convection, and now TD 22 is looking more tropical, with the circulation center positioned beneath the main convection. Wind shear is expected to fluctuate around 10 knots through Monday, which should allow some slow intensification. After that time, higher shear is expected. TD 22 is over water of 26 - 27C, which is just warm enough to support a tropical storm. However, its current track will push the storm just south of Bermuda on Sunday, where water temperatures fall below 26C, which may cause some temporary weakening before the waters warm up again. By Tuesday, when the storm is expected to turn north, water temperatures again fall below 26C, and slow weakening should result. However, the forecast beyond three days has a higher than usual level of uncertainty, because most of the computer models are forecasting that a second tropical cyclone may form behind TD 22 by Monday and steer the storm more to the west. In any case, intensification beyond a strong tropical storm is unlikely given the marginal sea surface temperatures and wind shear.


Figure 1.Sea Surface temperatures below TD 22 are just barely high enough to support a tropical storm. The blue color (26C) is the dividing line between temperatures that are warm enough and not warm enough to support a tropical storm.

What's behind TD 22?
The tropical disturbance we've been following about 750 miles east of the Lesser Antilles Islands has grown disorganized today, and now has 20 knots of shear over it. Development is not expected through Sunday of this system.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

Stan
Stan now ranks as one of the 30 most deadly hurricanes of all time, with over 1500 deaths caused. The grim task of recovering bodies in Guatemala continues today, where the entire town of Panabaj in western Guatemala was buried in a landslide, killing all 800 residents. Another 600 died in mudslides elsewhere in Guatemala. The storm also killed 67 people in El Salvador, 24 in Mexico and 11 in Nicaragua. Hundreds more are missing and presumed buried under landslides near Lake Atitlan in Guatemala. In a freakish double whammy, a magnitude 5.8 earthquake hit Guatemala Friday, causing additional damage, but no deaths. Also bizzare is the volcanic eruption that occured during the height of Stan rains in El Salvador on October 1. The eruption killed two and injured dozens. When you add these events to the magnitude 5.4 earthquake that rocked Taiwan at the height of Tyhoon Longwang on October 1, one might wonder if there is a connection between seismic activity and hurricane activity! There isn't.

October outlook
Historically, 20% of all Atlantic tropical storms have occured in the month of October. In a nomal year, this means we can expect two tropical storms, one of which becomes a hurricane. According to Dr. Bill Gray's October 2005 hurricane forecast issued on October 3, this year we can expect an above average October, with three tropical storms, two of which become hurricanes--one of those a major hurricane. We have already had two named storms this month, Stan and Tammy. Vince seems like a good bet by Sunday. Long range computer model forecasts continue to show that conditions for breeding tropical storms will be excellent until at least the last week of October, so two more named storms--Vince and Wilma--will likely result by October 21. This would tie 2005 with 1933 as the busiest hurricane season ever. It is interesting to note that in 1933, the final three storms all showed up after October 25. If 2005 follows a similar pattern, we'll have Alpha, Beta and Gamma in addition to Vince and Wilma before it's all over. Dr. Bill Gray is not forecasting any November storms to form. However, we should get at least one, given the current pattern and continued above-normal sea surface temperatures over the Atlantic.


Figure 2. Typical tropical storm formation areas for October.


The next update will be Sunday around 11 am, or later today if something interesting happens.

Jeff Masters

Two Atlantic areas to watch

By: JeffMasters, 2:04 AM GMT on October 08, 2005

System east of the Lesser Antilles
The tropical disturbance we've been following east of the Lesser Antilles Islands is now near 13N 49W, moving northwest at about 15 mph. It's convection diminished considerably this afternoon, but has made a comeback this evening. Wind shear over the system is conducive for slow tropical storm development, 5 - 10 knots. No surface circulation is evident on satellite imagery or QuikSCAT wind measurements, and this area is not likely to develop into a depression Saturday.


Figure 1. Model tracks for suspect area east of the Lesser Antilles Islands.

System northeast of Puerto Rico
A non-tropical 1012 mb low is northeast of Puerto Rico near 25n57w in the central Atlantic moving northwest at 10-15 mph. This low has been slowly gaining more and more deep convection today, and could become a tropical depression on Sunday. Wind shear over the system has dropped to about 5 knots today, which is favorable for tropical storm development. The latest 18Z (2pm EDT) runs of the GFS and GFDL models do not develop this system into a tropical storm, however.


Figure 1. Model tracks for the non-tropical low northeast of Puerto Rico.

Elsewhere in the tropics
All of the computer models agree that a tropical storm will form in the Caribbean or the region between Bermuda and Puerto Rico sometime in the next four days. We can discount the 18Z (2 pm EDT) run of the GFS model, which shows a hurricane developing near Puerto Rico in the face of 30 knots of wind shear Saturday night, and moving north to threaten Bermuda early next week. I do expect that Tropical Storm Vince will pop up sometime early next week, though, in the area north of Puerto Rico.

The next update will be Saturday around 11 am.

Jeff Masters

The tropics: unsettled, but no major threats

By: JeffMasters, 2:09 PM GMT on October 07, 2005

Florida
The large area of thunderstorms that broke off from Stan and formed a low pressure system just north of the western tip of Cuba is still there today, pumping plenty of moisture into Florida. This system will continue to bring heavy rains to Florida the next day or two, but is not a threat to develop into a tropical depression. This low pressure system will track northwards along the cold front over the East Coast and move out to sea off the Carolina coast this weekend, and is not expected to add to the 2-5 inches of rain Tammy's remnants are bringing to the Appalachians and New England the next two days.

Atlantic areas to watch
The tropical disturbance we've been following east of the Lesser Antilles Islands is now near 10N 46W. It's convection has diminished considerably today, and is not a threat to develop into a tropical depression over the next two days.

A non-tropical 1011 mb low is northeast of Puerto Rico near 22n56w in the central Atlantic moving west-northwest at 10-15 mph. Tropical development of this this low is not expected for the next two days, but could start to occur after that. The GFS model turns this into a tropical storm by Tuesday that meanders off the East Coast of the U.S., and eventually heads out to sea.


Figure 1. Model tracks for the non-tropical low northeast of Puerto Rico.

Elsewhere in the tropics
Unsettled weather characterize most of the tropical Atlantic, and we need to keep a watchful eye for new suspect areas that may crop up.

Stan
The death toll from Hurricane Stan stands at 250, and will undoubtedly go much higher, as news reports indicate two villages 100 km west of Guatemala City are buried and unreachable. Guatemala suffered the most, with 154 dead, while El Salvador lost 65, Mexico 17, and 14 died in Nicaragua, Honduras and Costa Rica. The remnants of Stan in the Pacific are no longer dumping heavy rain on the area, but the remnants of Stan in the Atlantic near Cuba are still pulling a moist flow of air across Central America, and are expected to bring rains of 1 - 2 inches today over much of the disaster area.

Wunderground member Norman (neavilag) in Guatemala sent me these 24 hour precipitation amounts observed in his country from Stan's rains between 8am Oct 4th and 8am Oct 5th. Up to 10.5 inches (in Spanish, pulgadas) in just 24 hours!

Retalhuleu 266mm (10.5 pulgadas)
Aduana Tecún Uman (Front Mexico) 265mm (10.5 pulgadas)
Pedro de Alvarado (Front El Salvador) 188mm (7.4 pulgadas)
San Jose 134mm (5.23 pulgadas)
Quetzaltenango 131mm (5.22 pulgadas)
Guatemala 70mm (2.75 pulgadas)

Stan's remains near Baja
The remants of Stan are still lurking near the Mexican coast by Puerto Vallarta, and still has the potential to develop into a tropical storm. This system will track northwestward over the next few days and threaten Baja California.

I'll update this by 4pm EDT if there is some significant development. Otherwise the next update will be Saturday around 11 am.

Jeff Masters

Nothing immediately coming to follow Tammy

By: JeffMasters, 7:55 PM GMT on October 06, 2005

Tammy
Tammy is still generating heavy rains of up to 1/2 inch per hour in North Carolina and South Carolina, but this storm has done its worst and no longer has any spin. A portion of the storm may pop back out over the Gulf of Mexico Friday, but no tropical storm development is expected, due to wind shear from an upper level low in the Gulf. A cold front is expected to arrive over the East Coast Friday, pulling the remains of Tammy northward up the front, drenching the entire East Coast. Rainfall amounts from Tammy will generally be in the 1 - 3 inch range along the coast, and 3 - 6 inches in the Appalachians, creating some localized flooding problems.

Stan Jr.
The large area of thunderstorms that broke off from Stan yesterday is now a 1004 mb low pressure system just north of the western tip of Cuba. This system has just a small area of deep convection to the southeast of the center. Upper-level outflow is apparent to the southeast, but nowhere else. Wind shear of about 10 knots from westerly upper-level winds is pushing the convection away from the center. Observations from Cuban radar confirm that this a poorly organized system with a few bands of heavy showers over western Cuba.

This system is expected to push northward the next two days, spreading heavy rain and high winds over western Cuba, the Florida Keys, and the Florida Peninsula. Development into a tropical depression is not likely, given the system's current disorganized state. This system no longer looks like a big rain-producer for Florida, and some of the flood watches posted for the state may be dropped later today if the system does not gain any more strength. Stan Jr. will continue to the northeast and dump another 1 -2 inches of rain on the areas already affected by Tropical Storm Tammy.


Figure 1. Model tracks for Stan Jr.--the tropical disturbance off of the Yucatan.

Stan
The death toll from Hurricane Stan still stands at 162, including 62 deaths in El Salvador, 79 in Guatemala, and 21 in Nicaragua, Mexico, and Honduras. The remnants of Stan are no longer dumping heavy rain on the area, and only scattered thunderstorms are expected in the disaster area the next five days.


Figure 2. Stan's observed rainfall from the NASA TRMM satellite. Rainfall amounts as high as 400 mm (16 inches) were observed along the coast.

Stan III?
The remants of Stan have formed a large area of intense convection near the Mexican coast by Puerto Vallarta, and winds of 40 - 50 mph have been observed in association with this system. However, no surface circulation has been observed yet, and this is not quite yet a tropical storm. This system will track northwestward over the next few days and threaten Baja California and the mainland Mexican coast.

Vince?
A tropical disturbance near 9N 43W, about 1100 miles east of the Lesser Antilles Islands, it looking more ragged this afternoon. It is not expected to become a tropical depression today. About 10 knots of shear from strong westerly winds is affecting the disturbance, but models indicate that this shear may decrease over the next day or two. The disturbance is moving west at 15 - 20 mph. A more northwestery motion is likely by Saturday, thanks to the steering influence of a large upper-level low pressure system at 25N 60W.


Figure 3. Model tracks for the mid-Atlantic disturbance.

Elsewhere in the tropics
Plenty of low pressure and light wind shear continue to characterize the rest of the tropics, and we need to keep a watchful eye for new suspect areas that may crop up.

Jeff Masters

After Tammy, what next?

By: JeffMasters, 1:42 PM GMT on October 06, 2005

Tammy
Tropical Storm Tammy came ashore at 7 pm EDT last night near the Florida Georgia border with sustained winds of 50 mph, a storm surge of 1 - 3 feet, and torrential rains. Rainfall amounts across southeast Georgia and coastal sections of
southeast South Carolina have been in the 2 to 7 inch range, with 2 inches or less across interior South Carolina. The highest rainfall totals between 4 and 7 inches have occurred between Folly Beach and Darien. Additional rainfall amounts of 2 to 4 inches are possible today. While numerous instances of urban and small stream flooding have been observed, no major flooding damage has been reported from Tammy.


Figure 1. Estimated rainfall from the Jacksonville radar.

Tammy is being drawn westward across Georgia by an upper level low over the northern Gulf of Mexico, and is expected to dissipate tonight. A cold front is expected to arrive over the East Coast Friday,pulling the remains of Tammy northward up the front, drenching the entire East Coast.

Stan Jr.
The large area of thunderstorms that broke off from Stan yesterday is now a 1005 mb low pressure system over the Yucatan Channel between Cuba and the Yucatan Peninsula. Satellite imagery shows a very disorganized system with the main cloudiness well east and north of the center. Not much upper-level outflow is apparent. Wind shear of about 10 knots from westerly upper-level winds is pushing the convection away from the center, towards the east. Observations from Cuban radar confirm that this a poorly organized system with a few bands of heavy showers over western Cuba.

This system is expected to push northward the next two days, spreading heavy rain and high winds over western Cuba, the Florida Keys, and the Florida Peninsula. Development into a tropical depression today is not likely, given the system's current disorganized state. Florida can expect conditions similar to those a tropical depression or weak tropical storm would bring, however, with rain amounts of 3 - 5 inches and high winds. The system will continue to the northeast and drench the areas already dumped on by Tropical Storm Tammy, and the entire East Coast will need to be concerned about flooding problems from this one-two punch.


Figure 2. BAMM and GFDL model tracks for Stan Jr.--the tropical disturbance off of the Yucatan.

Stan
The death toll from Hurricane Stan now stands at 162, including 62 deaths in El Salvador, 79 in Guatemala, and 21 in Nicaragua, Mexico, and Honduras. Unconfirmed reports from remote villages in Guatemala indicate that hundred more may be dead. Extensive deforestation in the high mountains where Stan's heavy rains fell contributed significantly to this disaster; the lack of tree cover allowed floodwaters to rampage down the mountainsides unchecked. The remnants of Stan will continue to pour heavy rains on this area today, but should ease off Friday.

Stan, who barely made it to Category 1 strength for a few hours, will likely have his name retired, thanks to this unfolding disaster. This would make the Hurricane Season of 2005 the first season to have five names retired (1955, 1995, and 2004 all had four storm names retired).


Figure 3. Stan's observed rainfall from the NASA TRMM satellite. Rainfall amounts as high as 400 mm (16 inches) were observed along the coast.

Stan III?
The remants of Stan have formed a large area of intense convection near the Mexican coast by Acapulco amd Puerto Vallarta, and appear likely to spin up into a new tropical depression today. This storm will track northwestward and threaten Baja and much of the Mexican Pacific coast.

Vince?
A tropical disturbance near 8N 43W, about 1200 miles east of the Lesser Antilles Islands, has developed a low level circulation, impressive deep convection, and the beginnings of an upper-level outflow channel to the north. About 10 knots of shear from strong westerly winds is affecting the disturbance, but models indicate that this shear may decrease over the next day or two. The disturbance is moving west at 15 - 20 mph. A more northwestery motion is likely by Saturday, thanks to the steering influence of a large upper-level low pressure system at 25N 60W.

The disturbance is pretty far south for development to occur, and I don't expect a tropical depression here today. Development is more likely Friday or Saturday, when the disturbance will be further from the equator and can take advantage of the Earth's spin to help it develop.


Figure 4. BAMM and GFDL model tracks for the mid-Atlantic disturbance.

Elsewhere in the tropics
Conditions are expected to be unusually conducive for tropical storm formation throughout the Atlantic for the next 10 days, and it is quite likely we'll make it to the end of the alphabet by mid-October. When that happens, we go Greek--Alpha, Beta, and hopefully not much further into the Greek Alphabet!

Jeff Masters

Tammy, Stan Jr., Stan, and Stan III--and Vince?

By: JeffMasters, 7:55 PM GMT on October 05, 2005

Tammy
The 5:16 pm EDT Hurricane Hunter mission found winds of 51 knots at flight level, supporting Tammy's maximum winds staying at 50 mph. The pressure fell 1 mb to 1002 mb, so Tammy is not strengthening rapidly, nor is she expected to. Tammy is maintaining her strength in the presence of some unusually high wind shear, about 20 - 25 knots. Tammy is poorly organized, and radar animations out of Jacksonville, Florida, show no sign of an eyewall forming, just a mass of disorganized echoes to the northeast of the center. No ships or buoys have actually measured tropical storm-force sustained winds of 40 mph yet. It is likely that Tammy will move onshore tonight as a weak tropical storm with maximum winds in the 50 - 55 mph range, and a storm surge of 2 - 4 feet.

The primary threat from Tammy will be from her rains. Bands of heavy rain continue to pound the coasts of northern Florida, Georgia, and the Carolinas. Rainfall amounts as of 4 pm EDT have mainly been in the 1 to 3 inch range along the coast in Georgia and along the South Carolina and northern Florida coasts, with lesser amounts further inland. A few isolated areas have received up to five inches--for example, Brunswick Georgia, and just south of Jacksonville, Florida. Storm total rainfall amounts of 3 to 5 inches are expected with isolated amounts of 8 to 10 inches along and to the north of Tammy's path. Flooding problems will be most serious in coastal Georgia, which received 3 - 5 inches of rain this past week, before Tammy came along.


Figure 2. Estimated rainfall from the Jacksonville radar.

Tammy is being drawn northward by an upper level low over the northern Gulf of Mexico. The counter-clockwise flow of air around this low will pull Tammy northwestward into Georgia, and perhaps even westward towards Alabama by Friday. A cold front is expected to arrive over the East Coast by Friday, and the remains of Tammy are expected to track up the front, drenching the entire East Coast.

Stan Jr.
A large area of thunderstorms broke off from Stan this morning, and emerged into the Yucatan Channel. Satellite imagery shows upper level outflow has developed to the north and east, along with some low-level spiral banding. There is a circulation center near the northeast tip of the Yucatan Peninsula, with a limited amount of deep convection to the northeast and east. Wind shear from westerly upper-level winds are pushing this convection away from the center. Observations from the Cancun radar indicate two major spiral bands have formed, one on the southeast side and one on the north side. The overall impression is of a weak sheared system that is not yet a tropical depression strength. Once the center moves further out into ocean, the system has a better chance for intensification. With wind shear of 10 knots over it, I believe this will be a tropical depression by tomorrow as the system tracks north-northeast towards western Florida. If this system were to be named, it would get the new name Vince, and not Stan, since the primary circulation of that storm pushed into the Pacific Ocean this morning. This assumes that the developing disturbance doesn't become a tropical storm first and steal the name Vince, leaving Stan Jr. stuck with the name Wilma.

Regardless of whether or not this system develops into a tropical storm, southwest Florida can expect tropical storm conditions, with rain amounts of 3 - 5 inches and high winds Thursday and Friday. The system will continue to the northeast and drench the areas already dumped on by Tropical Storm Tammy, and the entire East Coast needs to be concerned about serious flooding problems from this one-two punch.


Figure 1. BAMM model track for Stan Jr.--the tropical disturbance off of the Yucatan.

Stan
The death toll from Hurricane Stan now stands at 103, including 50 deaths in El Salvador, 34 in Guatemala, 11 in Nicaragua and eight in Mexico. The remnant circulation from Stan continues to pull moist tropical air from the Pacific Ocean into the disaster areas, where more flooding rains are expected to make the disaster even worse. Stan, who barely made it to Category 1 strength for a few hours, will likely have his name retired, thanks to this unfolding disaster. This would make the Hurricane Season of 2005 the first season to have five names retired (1955, 1995, and 2004 all had four storm names retired).

Stan III?
The remants of Stan appear likely to spin up into a new tropical cyclone that may threaten Baja California later in the week. If both this system and the Stan Jr. system off of the Yucatan do become tropical storms, this would be the first time a dissipated hurricane spawned two new tropical cyclones, one in the Atlantic and one in the Pacific. How many firsts can this season have??

Vince? Wilma?
A tropical disturbance near 9N 40W, 1500 miles east of the Lesser Antilles Islands, has developed a low level circulation, impressive deep convection, and the beginnings of an upper-level outflow channel to the north. About 10 knots of shear from strong westerly winds is affecting the disturbance, but models indicate that this shear may decrease over the next day or two. The disturbance is moving west at 15 - 20 mph. The early track forecasts are performing poorly--they have the disturbance moving to the northwest, and it is not doing so. However, a more norhtwestery motion is likely by Saturday, thanks to the steering influence of a large upper-level low pressure system at 25N 60W.

The disturbance is pretty far south for development to occur, but this hurricane season has had little regard for what is usual. Thus, the disturbance may form into a tropical depression on Thursday. Development is more likely Friday or Saturday, when the disturbance will be further from the equator and can take advantage of the Earth's spin to help it develop.


Figure 3. BAMM and GFDL model tracks for the mid-Atlantic disturbance.

Elsewhere in the tropics
Conditions are expected to be unusually conducive for tropical storm formation throughout the Atlantic for the next 10 days, and it is quite likely we'll make it to the end of the alphabet by mid-October. When that happens, we go Greek--Alpha, Beta, and hopefully not much further into the Greek Alphabet! One positive sign today that the Hurricane Season of 2005 will eventually end--a blizzard warning is up for western Montana.

Jeff Masters

New threat: Stan's remains head for Florida

By: JeffMasters, 4:34 PM GMT on October 05, 2005

Return of Stan
A large area of thunderstorms broke off from Stan this morning, and has emerged into the Yucatan Channel. Satellite imagery this morning has shown some improved organization of this feature, and with wind shear 10 knots over it, there is a chance of a tropical depression or tropical storm forming later today or tomorrow as the system tracks north-northeast towards western Florida. If this system were to be named, it would get the new name Vince, and not Stan, since the primary circulation of that storm pushed into the Pacific Ocean this morning.

Winds at the NOAA buoy 42056 at 20N 85W in the Yucatan Channel just switched from easterly to westerly at 11 am EDT today, suggesting that a closed circulation has already formed. Winds at this buoy were 25 mph gusting to 34 mph, and wind estimates from the latest QuikSCAT satellite pass were as high as 45 mph in this region. Regardless of whether or not this system develops into a tropical storm, southwest Florida can expect tropical storm conditions Thursday afternoon when this system comes ashore. The system will continue to the northeast and drench the areas already dumped on by Tropical Storm Tammy, and the entire East Coast needs to be concerned about serious flooding problems from this one-two punch.

I'll update this blog by 4pm today. The remainder of this morning's blog appears below, unchanged.


Figure 1. BAMM model track for tropical disturbance off of the Yucatan.

Tammy
Tropical Storm Tammy formed 20 miles offshore from Cape Canaveral this morning. With 19 named storms, the Hurricane Season of 2005 has now tied 1995 as the second busiest ever. Only 1933, with 21 storms, has had more.

Tammy formed in the presence of some unusually high wind shear from an upper-level low pressure system in the Gulf of Mexico--about 15 - 20 knots--which is decreasing enough this morning to allow some intensification. Radar animations out of Melbourne, Florida, show an intense area of thunderstorms, well offshore, that are increasing in echo intensity. No ships or buoys have actually measured tropical storm-force sustained winds of 40 mph yet, but it is likely that such winds are occurring in the most intense convection to the east of the center. Infrared satellite images confirm that this area is growing in size and intensity, and some very cold cloud tops are now appearing. As long as the center remains offshore, Tammy may continue to intensify. Intensification into a hurricane is not expected, and would be a major surprise, due to the high wind shear. It is more likely that the center will move onshore tonight as a weak tropical storm with maximum winds in the 40 - 50 mph range. In any case, the primary threat from Tammy will be from her rains. Bands of heavy rain will move onshore the coasts of northern Florida, Georgia, and the Carolinas over the next few days, creating flooding problems, particulary in Georgia, where the precipitation will be heaviest and the soil is moister.


Figure 2. Mild drought conditions cover South Carolina, which will slow flooding in that state. Flooding is more likely to be a problem in Georgia and perhaps North Carolina, where the soil is moister.

Tammy is being drawn northward by a trough and its associated cold front that are expected to arrive over the East Coast on Friday. The remains of Tammy will track up the front, drenching the entire East Coast, and it is likely that at least one more area of low pressure--probably not a tropical storm, but it could be--will develop along the front late in the week and move northeast, giving the entire East Coast additional heavy rain.

Stan's wake
Stan dissipated this morning over the Mexican mountains, and his circulation is pushing onward into the Pacific Ocean, where a new tropical storm may form. Little enough of Stan remains in the southern Gulf of Mexico to allow a new tropical storm to form there later in the week, although the NOGAPS model is still calling for that to happen.

Stan's onshore winds blowing across the Pacific Ocean into his center caused a major disaster in El Salvador, Guatemala, Honduras, Nicaragua, and Mexico. In Mexico's southernmost state of Chiapas, a river overflowed its banks and tore through the city of Tapachula, destroying numerous houses. Guatemala is reporting four dead, Nicaragua nine dead, and 49 have been killed in El Salvador by mud slides triggered by heavy rains. The death toll will undoubtedly rise much higher, since Stan's remains will still generate rain over the area for two more days.

Elsewhere in the tropics
The area of disturbed weather near Puerto Rico has diminished, and tropical storm formation is not expected here or anywhere else in the Atlantic through Thursday.

I'll have an update about 3pm today when the Hurricane Hunters arrive at the storm.

Jeff Masters

New threat: Stan's remains head for Florida

By: JeffMasters, 1:07 PM GMT on October 05, 2005

Return of Stan
A large area of thunderstorms broke off from Stan this morning, and has emerged into the Yucatan Channel. Satellite imagery this morning has shown some improved organization of this feature, and with wind shear 10 knots over it, there is a chance of a tropical depression or tropical storm forming later today or tomorrow as the system tracks north-northeast towards western Florida. If this system were to be named, it would get the new name Vince, and not Stan, since the primary circulation of that storm pushed into the Pacific Ocean this morning.

Winds at the NOAA buoy 42056 at 20N 85W in the Yucatan Channel just switched from easterly to westerly at 11 am EDT today, suggesting that a closed circulation has already formed. Winds at this buoy were 25 mph gusting to 34 mph, and wind estimates from the latest QuikSCAT satellite pass were as high as 45 mph in this region. Regardless of whether or not this system develops into a tropical storm, southwest Florida can expect tropical storm conditions Thursday afternoon when this system comes ashore. The system will continue to the northeast and drench the areas already dumped on by Tropical Storm Tammy, and the entire East Coast needs to be concerned about serious flooding problems from this one-two punch.

I'll update this blog by 4pm today. The remainder of this morning's blog appears below, unchanged.


Figure 1. BAMM model track for tropical disturbance off of the Yucatan.

Tammy
Tropical Storm Tammy formed 20 miles offshore from Cape Canaveral this morning. With 19 named storms, the Hurricane Season of 2005 has now tied 1995 as the second busiest ever. Only 1933, with 21 storms, has had more.

Tammy formed in the presence of some unusually high wind shear from an upper-level low pressure system in the Gulf of Mexico--about 15 - 20 knots--which is decreasing enough this morning to allow some intensification. Radar animations out of Melbourne, Florida, show an intense area of thunderstorms, well offshore, that are increasing in echo intensity. No ships or buoys have actually measured tropical storm-force sustained winds of 40 mph yet, but it is likely that such winds are occurring in the most intense convection to the east of the center. Infrared satellite images confirm that this area is growing in size and intensity, and some very cold cloud tops are now appearing. As long as the center remains offshore, Tammy may continue to intensify. Intensification into a hurricane is not expected, and would be a major surprise, due to the high wind shear. It is more likely that the center will move onshore tonight as a weak tropical storm with maximum winds in the 40 - 50 mph range. In any case, the primary threat from Tammy will be from her rains. Bands of heavy rain will move onshore the coasts of northern Florida, Georgia, and the Carolinas over the next few days, creating flooding problems, particulary in Georgia, where the precipitation will be heaviest and the soil is moister.


Figure 1. Mild drought conditions cover South Carolina, which will slow flooding in that state. Flooding is more likely to be a problem in Georgia and perhaps North Carolina, where the soil is moister.

Tammy is being drawn northward by a trough and its associated cold front that are expected to arrive over the East Coast on Friday. The remains of Tammy will track up the front, drenching the entire East Coast, and it is likely that at least one more area of low pressure--probably not a tropical storm, but it could be--will develop along the front late in the week and move northeast, giving the entire East Coast additional heavy rain.



Stan's wake
Stan dissipated this morning over the Mexican mountains, and his circulation is pushing onward into the Pacific Ocean, where a new tropical storm may form. Little enough of Stan remains in the southern Gulf of Mexico to allow a new tropical storm to form there later in the week, although the NOGAPS model is still calling for that to happen.

Stan's onshore winds blowing across the Pacific Ocean into his center caused a major disaster in El Salvador, Guatemala, Honduras, Nicaragua, and Mexico. In Mexico's southernmost state of Chiapas, a river overflowed its banks and tore through the city of Tapachula, destroying numerous houses. Guatemala is reporting four dead, Nicaragua nine dead, and 49 have been killed in El Salvador by mud slides triggered by heavy rains. The death toll will undoubtedly rise much higher, since Stan's remains will still generate rain over the area for two more days.

Elsewhere in the tropics
The area of disturbed weather near Puerto Rico has diminished, and tropical storm formation is not expected here or anywhere else in the Atlantic through Thursday.

I'll have an update about 3pm today when the Hurricane Hunters arrive at the storm.

Jeff Masters

Florida gets soaked; Stan a major disaster in Central America

By: JeffMasters, 8:55 PM GMT on October 04, 2005

Tropical disturbance approaching Florida
The leading portion of the tropical disturbance over the central Bahama Islands has moved ashore in Central Florida today, bringing rains of up to three inches and wind gusts of 40 mph along the coast. Although the disturbance is not a threat to develop into a tropical depression today, the impact on Florida will be similar to that of a tropical depression--sustained winds of 30 mph, with gusts to 45 mph along the coast, along with 3 - 6 inches of rain and large battering waves. The disturbance currently has a weak surface circulation center just south of Andros Island. The shear over the storm is high, 10 - 20 knots, and development into a tropical depression is not possible until Wednesday or Thursday, when the shear may drop below 10 knots. However, the disturbance will be near or over the Florida Peninsula when that happens, limiting the chances for development. I believe that this system will not develop into a tropical depression at all. Instead, the disturbance will interact with an upper-level low pressure system and cold front on Thursday, and become a large--and very wet--ordinary low pressure system. This low will pump copious amounts of tropical moisture into Florida, Georgia, and the Carolinas over the next three days. By Thursday, a cold front swings onto the East Coast, and several areas of low pressure--all non-tropical--are expected to develop along the front Thursday through Saturday and move northeast, giving the entire East Coast drenching tropical rains.


Figure 1.Storm total rainfall from the Melbourne radar.

I speculated about the possibility yesterday of a tropical storm forming near the Carolinas and moving northwards along the coast. This is no longer expected, due to the high wind shear over the region.


Figure 1. BAMM and GFDL model forecast tracks of Bahamas tropical disturbance. The intensity forecast numbers from the SHIPS model are far too high; this system will be lucky to develop into a tropical depression.

Tropical Storm Stan
Stan stormed ashore on the coast of Mexico this morning as a Category 1 hurricane with 80 mph winds, and is expected to finally dissipate Wednesday morning over the Mexican mountains. The onshore winds blowing across the Pacific Ocean into the center of Stan have caused a major disaster in El Salvador, Guatemala, Honduras, Nicaragua, and Mexico. Guatemala is reporting four dead and many communities cut off by rising rivers, and 38 have been killed in El Salvador by mud slides triggered by heavy rains. The death toll will undoubtedly rise much higher. Since Stan's remains are going nowhere fast, as much as 20 inches of rain could fall over the next few days over the mountainous regions of these countries.

Stan's remains may re-organize and form of a new tropical storm over the Pacific, which could move northwest and threaten Baja later in the week. The NOGAPS and GFDL models predict that Stan's remains will linger over the Gulf of Mexico long enough to result in the formation of a new tropical storm there by the weekend. All this will depend on Stan's track; it is very unlikely we would get a new storm in both ocean basins.

Elsewhere in the tropics
Clouds from the tropical disturbance over the Bahamas extend southeastward to Puerto Rico and the Lesser Antilles Islands. The area of disturbed weather near Puerto Rico bears watching, as wind shear values here are 5 - 10 knots, the lowest of anywhere in this disturbance.

The region between Africa and the Lesser Antilles is quiet.

Jeff Masters

Stan storms ashore; Florida getting pounded by a powerful tropical disturbance

By: JeffMasters, 1:40 PM GMT on October 04, 2005

Tropical disturbance approaching Florida
The tropical disturbance over the central Bahama Islands is poised to hit Florida Tuesday night and Wednesday with heavy rains and high winds. Although the disturbance is not a threat to develop into a tropical depression today, the impact on Florida will be similar to that of a tropical depression--sustained winds of 30 mph, with gusts to 45 mph along the coast, along with 3 - 6 inches of rain and large battering waves. The disturbance currently has a weak surface circulation center just south of Andros Island. There is no cloud cover on the west side of the circulation center, and shearing winds blowing from the west are keeping all of the convection pushed over to the east side of the disturbance. Contrary to yesterday's computer model projections of much reduced shear affecting the disturbance, the shear over the storm has almost doubled, to 20 - 30 knots. This shear is in part associated with strong upper-level outflow flowing northeastward out of Hurricane Stan. No development of any kind is possible while the shear remains this strong, and I believe that this system will not develop into a tropical depression at all. Instead, the disturbance will interact with an upper-level low pressure system forecast to develop in the Gulf of Mexico on Wednesday, and become a large--and very wet--ordinary low pressure system. This may also turn into hybrid system called a subtropical storm--a system that is similar to a tropical storm, but has its main winds 100 miles or so away from the center. If this happens, the system will be named Subtropical Storm Tammy. Our skill in forecasting these types of hybrid systems is low.

Once in the Gulf of Mexico, the storm is expected to meander for several days, until a cold front pushes into northern Florida Friday and pulls the storm northeastward across Florida and the Carolinas on Thursday through Saturday, dumping very heavy rains across the region. At the same time, another low pressure area may form along the front near the Carolinas and move northeastward across New England. This second low is not expected to be tropical in nature, but will still dump a lot rain and bring high winds to the East Coast.

I speculated about the possibility yesterday of a tropical storm forming near the Carolinas and moving northwards along the coast. This no longer seems likely, due to the high wind shear over the area today.


Figure 1. BAMM model forecast track of Bahamas suspect area. The intensity forecast numbers from the SHIPS model are far too high; this system will be lucky to make it to tropical storm strength (40 mph winds).

Hurricane Stan
Hurricane Stan presents a classic example of why the National Hurricane Center issues hurricane warnings for a much larger area of coast than seems reasonable. Stan made a sudden turn to the southwest last night and speeded up his forward speed from 6 mph to 10 mph, and is now making landfall on the coast of Mexico, a full 24 hours before expected. This change of course and speed were completely unanticipated my any of the forecast models. However, since the NHC was conservative, the area of the coast the eye of Stan is hitting has been under a hurricane warning for a full day, so the sudden turn should not catch the affected area completely unprepared. Why did the models miss this turn? Perhaps because of Stan's interaction with the mountainous terrain nearby, or because of interaction with the developing upper-level low pressure system in the Gulf of Mexico.

Elsewhere in the tropics
Clouds from the tropical disturbance over the Bahamas extend southeastward to Puerto Rico and the Lesser Antilles Islands. The area of disturbed weather near Puerto Rico bears watching, as wind shear values here are 5 - 10 knots, the lowest of anywhere in this disturbance.

The region between Africa and the Lesser Antilles is quiet.

Jeff Masters

Florida to get socked; Stan looking strong

By: JeffMasters, 8:33 PM GMT on October 03, 2005

Tropical disturbance approaching Florida
An tropical disturbance approaching the central Bahama Islands is poised to sock Florida Tuesday night and Wednesday with heavy rains and high winds. While the shear is a high 10 - 20 knots over the system today, the shear is expected to decrease to 5 - 10 knots tomorrow, accompanied by the formation of an upper-level anticyclone on top. This system has the potential to develop into a tropical depression by the time it reaches Florida, and a reconnaissance flight is scheduled for Tuesday at 11 am. The disturbance currently has no surface circulation center; the spinning clouds seen on satellite images at 25N 70W are from an upper-level low that the disturbance is now separating from. Beaches along central Florida are already suffering erosion from the large pounding waves emanating from this disturbance.

The forecast track of this disturbance is complicated by the expected interaction with a cold front forecast to move over the East Coast by the end of the week, and an upper-level low pressure system expected to form in the northern Gulf of Mexico on Wednesday. The GFS model shows the disturbance splitting into two storms, one that tracks across Southern Florida into the Gulf of Mexico, and the other which moves northward along the coast, brushing the Carolinas and New England. Neither storm has a very good chance to develop into a hurricane. Anything moving into the Gulf will encounter the upper-level low and its shearing winds. An East Coast storm would have low shear and a favorable upper-level winds for development, but not much time over warm water. Regardless, Florida is in for a very wet week with potential serious flooding problems, both from the rains of the tropical disturbance, and from the upper-level low, which is likely to entrain copious tropical moisture over the state.


Figure 1. BAMM model forecast track of Bahamas suspect area. The intensity forecast numbers from the SHIPS model are far too high; this system will be lucky to make it to tropical storm strength (40 mph winds). The GFS and NOGAPS models are tracking the upper-level low northeast of the Bahamas instead of the surface tropical wave.

Tropical Storm Stan
There have been three center penetrations of Stan this afternoon by the Hurricane Hunters, most recently at 4:50 pm EDT. The central pressure fell 6 mb in the three hours between passes, and the highest winds measured were in the 55 - 60 mph range. Satellite imagery continues to show an improving outflow pattern, larger area of deep convection near the center, and more low-level spiral banding. The chances for continued intensification are high, as Stan is over 30C waters and is positioned under a large anticyclone that will provide good outflow and wind shear values below 5 knots. Stan will probably be a Category 1 hurricane as it approaches the Mexican coast on Wednesday, and a Category 2 hurricane is not out of the question.

The 12Z ( 8am EDT) model runs continue to forecast a landfall in Mexico between Tampico and Veracruz on Wednesday. After briefly stalling this afternoon while re-organizing, Stan is moving westward again at about 6 mph under the influence of a strong ridge of high pressure. This ridge is forecast to weaken as a weak trough of low pressure swings across the U.S. and drops a cold front and upper-level low pressure system across the northern Gulf of Mexico by Thursday. In response to this weakening, Stan is expected to slow down as he approaches the coast Tuesday, but it is looking less and less likely that Stan will stall in the Gulf and wander erratically.

Mid-Atlantic disturbance
A low pressure system accompanied by a concentrated area of thunderstorms is halfway between Africa and the Lesser Antilles Islands, at about 14N 36W. This system is fighting significant wind shear, and will probably not develop into a tropical depression. It is expected to move northward the next five days over open waters and not threaten any land areas.

Jeff Masters

A complex and dangerous situation

By: JeffMasters, 1:55 PM GMT on October 03, 2005

The tropics today present a very complex picture, with many potential areas of danger for all residents along the Mexican and U.S. coast. Here's what's happening:

Tropical Storm Stan
Tropical Storm Stan is quickly re-organizing over waters of the southwestern Gulf of Mexico. The chances for continued intensification a are high, as Stan is over 30C waters and is positioned under a large anticyclone that will provide good outflow and wind shear values below 5 knots. Stan will probably be a Category 1 hurricane as it approaches the Mexican coast on Wednesday, and a Category 2 hurricane is not out of the question.

The forecast of a landfall in Mexico between Tampico and Veracruz on Wednesday has increased in confidence since yesterday, but is still uncertain. Stan is being driven westward at 10 mph by a strong ridge of high pressure. This ridge will gradually weaken Tuesday as a weak trough of low pressure swings across the U.S., and Stan will slow down in response. All of the models are now forecasting that the ridge will remain strong enough to carry Stan all the way to the coast. However, there is still a distinct chance that Stan may stall just before the coast, or make landfall, then pop back out over the Gulf of Mexico and re-intensify. Stan may then remain in the Gulf many days, and may eventually move north and threaten the U.S.

Complicating the forecast is the fact that a tropical depression my form tomorrow along the Pacific Mexican coast in the Gulf of Tehuantepec, 100 miles south of the Gulf of Mexico. Storm-storm interactions among two tropical storms are not well understood, and the development of a new tropical depression on the other side of Mexico will make the current forecasts of Stan's motion Wednesday and beyond very dubious. And to complicate matters further, a non-tropical low pressure system is forecast to form over the Gulf of Mexico by Thursday, potentially making a set of three storms that will all interact in unpredictable ways. One positive note about this development is that the upper-level winds associated with this new non-tropical low would bring significant wind shear and weaken Stan--if he is still there. If Stan is not there, at least one model (the UKMET) suggests that this non-tropical low would meander over the Gulf of Mexico for many days, and potentially acquire tropical characteristics and become a tropical storm.

The larger threat to the U.S.?
The greater threat to the U.S. may be the spinning area of intense thunderstorms approaching the central Bahama Islands. This system is an upper-level low pressure system that is interacting with a surface trough of low pressure, and slowly making the transition from a cold-cored non-tropical low to a warm-cored tropical system. While the shear is a high 20 knots over the system today, the shear is expected to decrease to 10 knots tomorrow, accompanied by the formation of an upper-level anticyclone on top. This system has the potential to become a tropical depression tomorrow, and a reconnaissance flight is scheduled for Tuesday at 11 am. Model projections indicate the entire East Coast from Florida to the Carolinas to New England may be at risk from this system. This storm may strike Florida as a tropical depression or weak tropical storm on Wednesday morning. Beaches along central Florida are already suffering erosion from the large pounding waves emanating from this disturbance.


Figure 1. BAMM model forecast track of Bahamas suspect area.

Mid-Atlantic disturbance
A low pressure system accompanied by a concentrated area of thunderstorms has developed this morning halfway between Africa and the Lesser Antilles Islands, at about 14N 36W. This system has some impressive spiral banding, but is now fighting some significant wind shear, and looks less likely to develop into Tropical Depression 21. It is expected to move northward the next five days over open waters and not threaten any land areas.

Tropical Storm Otis
Tropical Storm Otis has decayed to a 40-mph tropical storm, and is forecast to remain just offshore Baja California and continue to weaken and eventually dissipate two days from now. Otis is not likely to cause any problems for Mexico or Arizona.

Jeff Masters

Stan about to leave the Yucatan

By: JeffMasters, 1:29 AM GMT on October 03, 2005

Tropical Storm Stan
Tropical Storm Stan is holding together as it moves has weakened during its passage across the Yucatan Peninsula, and is probably a tropical depression. There is very little deep convection surrounding the system, although the upper level ouflow is still good on all sides except the west.

Stan will have to re-organize once it pops out into the Gulf of Mexico Monday, and will have 36 hours or so to intensify over the warm 29 - 30C waters of the Gulf as it tracks westward. Wind shear is expected to remain very low, under 5 knots, and Stan could be a Category 1 hurricane as it approaches the Mexican coast on Tuesday. The latest model runs are still split on whether of not Stan will make it ashore on Tuesday. Two reliable models--the GFDL and Canadian--take Stan across Mexico and redevelop him as a tropical storm in the Pacific. However, the other models aren't so sure, and weaken the ridge that is driving Stan westward, allowing Stan to stall, loop back, or even turn northwards and threaten the U.S. later in the week. If Stan does stall and head northwards towards the U.S., he will have to contend with a large upper-level low pressure system forecast to form in the Gulf of Mexico by Thursday that would bring significant wind shear and weaken him.

Complicating the long range forecast is the fact that most of the computer models expect a second tropical storm to form nearby late in the week. The formation location varies depending upon which model one looks at. Two models indicate a storm will form off the east coast of Florida and scrape the Carolina coast (GFS and NOGAPS). The UKMET forms a storm near New Orleans and tracks it south into the Bay of Campeche; and the GFDL sees a new storm forming in the Yucatan Channel by the western tip of Cuba. We also need to keep an eye on the large area of thunderstorms approaching the Bahamas from the east, which could develop into a tropical storm later in the week.

Suffice to say, the waters surrounding the U.S. are expected to be very unsettled over the coming week, and this is a dangerous period of hurricane season for us. Ocean temperatures are still very warm, and the forecast is for very light wind shear over much of the hurricane breeding grounds.

Tropical Storm Otis
Tropical Storm Otis has decayed to a 45-mph tropical storm, and is forecast to continue to weaken and dissipate over the next three days. If Otis comes ashore in the Baja Peninsula, flooding and wind damage will be minimal. Otis's remains will probably not affect Arizona's weather.

Taiwan and China
Typhoon Langwang (Chinese for Dragon King), made landfall on Taiwan at dawn Sunday as a Category 3 typhoon with 120 mph winds. Passage over the 10000 foot high mountains of Taiwan significantly weakened Longwang, which struck mainland China today as a Category 1 hurricane. Longwang did heavy damage on Taiwan, killing 2,and injuring 46 people. In a freakish double-whammy, a magnitude 5.4 earthquake hit the island as Longwang came ashore, but did little damage.

Jeff Masters

Yucatan Stan

By: JeffMasters, 2:09 PM GMT on October 02, 2005

Tropical Storm Stan
Tropical Storm Stan is holding together as it moves slowly across the Yucatan Peninsula. Stan came ashore this morning as a 45-mph tropical storm just south of Cozumel Island, the same place Hurricane Emily hit earlier this season. Stan looks pretty good for a storm whose circulation is over land--some impressive spiral bands lie to the east over the Caribbean, and the upper level ouflow is good on all sides except the west. The wind shear is a low 5 knots over the storm.

Stan will have to re-organize once it pops out into the Gulf of Mexico Monday, and will have at least 36 hours or so to intensify over the warm 29 - 30C waters of the Gulf as it tracks westward towards the northeast coast of Mexico. Wind shear is expected to remain very low, under 5 knots, and Stan could be a Category 1 hurricane as it approaches the Mexican coast south of Brownsville on Tuesday. It is not certain Stan will make it ashore on Tuesday, as the ridge that is driving Stan westward is forecast to weaken. Stan may stall, loop back, or even turn northwards and threaten the U.S. later in the week. Complicating the long range forecast is the fact that most of the computer models expect a second tropical storm to form in the region by Wednesday or Thursday. The formation location varies depending upon which model one looks at, but ranges from Key West to Cedar Key to west of Jamaica to the southern Bahama Islands, or possibly the Carolina coast.

Tropical Storm Otis
Hurricane Otis is now Tropical Storm Otis, with 70 mph winds. Otis is looking like much less of a threat to Mexico and Arizona today. This is a small storm, and is expected to weaken further before it crosses the Baja Peninsula Monday, bringing at most 3 - 6 inches of rain to that region. By the time Otis makes it to northern Mexico, the storm will have dissipated, and should bring only 2 -4 inches of mostly beneficial rains to drought-starved southern Arizona.

TD 19
Tropical Depression 19 is struggling with wind shear, and is not expected to live long. It is unlikely that this storm will get a name, and instead be torn apart by wind shear within three days as it heads northward over open ocean, far from land.

Elsewhere in the tropics
The disturbed area of weather that was 500 miles east of Trinidad and the southern Lesser Antilles Islands has diminshed, and tropical storm developement in this area is not expected. An area of clouds north of Puerto RIco is primarily due to a upper-level low, and development is not expected.

Taiwan and China
Typhoon Langwang (Chinese for Dragon King), made landfall on Taiwan at dawn Sunday as a Category 3 typhoon with 120 mph winds. Passage over the 10000 foot high mountains of Taiwan significantly weakened Longwang, which is expected to strike mainland China today as a Category 1 hurricane. Longwang did heavy damage on Taiwan, injuring at least 36 people. In a freakish double-whammy, a magnitude 5.4 earthquake hit the island as Longwang came ashore. No damage reports from the earthquake have been received yet.

My next update will be at 10pm EDT tonight.
Jeff Masters

TD 20 intensifies

By: JeffMasters, 8:15 PM GMT on October 01, 2005

Tropical Depression 20
Tropical Depression 20 is intensifying as it moves slowly towards the Yucatan Peninsula. More spiral banding is evident on satellite imagery this afternoon, and the storm now has two good outflow channels, to the north and the south. The wind shear has fallen significantly, and is now just 5 knots out of the east. The center of the depression is about 70 miles south of buoy 42056, which itself is about 100 miles southeast of Cancun, Mexico. The buoy recently measured sustained winds of 34 mph gusting to 40 mph. A hurricane hunter aircraft measured peak winds of 30 mph in the southeast quadrant of the storm at 3 pm EDT today.

The system is expected to cross the Yucatan Peninsula Sunday, and will have to re-organize once it pops out into the Gulf of Mexico Monday. It will then have at least 36 hours or so to intensify over the warm 29 - 30C waters of the Gulf. Wind shear is expected to remain very low, under 5 knots, and TD 20 may be a strong tropical storm or Category 1 hurricane as it approaches the Mexican coast south of Brownsville on Tuesday. The forecast track is problematic, as none of the forecast models did a good job initializing this small and weak system this morning. Several models get confused about the identity of this system, and try to develop another tropical storm near the Florida Keys on Tuesday, and still keep this storm in the southwest Gulf of Mexico. The Canadian model suggests that TD 20 will threaten the northeast Mexican coast, but move northward and threaten Texas as well. The coast of northeast Mexico well south of Texas is the most likely target suggested by the rest of the models, but we won't have a good idea of where TD 20 will go until Sunday morning, after the 00Z (8pm EDT) model runs are available.

Hurricane Otis threatening Baja and Arizona
Hurricane Otis reached its peak intensity early this morning--a Category 2 hurricane with winds of 105 mph. Otis is now a Category 1 hurricane with 85 mph winds, and is expected to slowly creep northwestward over cooler waters and gradually weaken. By the time it takes a more northerly track and crosses the Baja Peninsula on Monday, Otis will probably be a strong tropical storm or weak Category 1 hurricane. Hurricane force winds extend outwards only 15 miles from Otis's center, so only a small portion of the coast will receive wind damage. Heavy rains of 5 - 10 inches will be the main problems with Otis, potentially triggering serious flash flooding in the desert mountains of Mexico. By Tuesday, portions of southern Arizona may receive 3 - 5 inches of rain, creating flash flooding problems there.


Figure 2. Hurricane Otis.

TD 19
Tropical Depression 19 is far out over the Atlantic Ocean, about 600 miles west-southwest of the Cape Verdes Islands. The environment for strengthening is fair, and we will probably see this system become a tropical storm tonight. A hurricane seems unlikely, as this system is expected to move northwest or northward for the next five days into a region of increasing wind shear. It will be interesting to see if this storm or TD 20 wins the race to become Stan--loser gets the name Tammy. If they both get upgraded on the same advisory, how does NHC decide which storm gets which name? I'm not sure the problem has ever arisen, and I hope they do something scientific like play a game of Rock, Paper, Scissors to decide.

Disturbance 500 miles east of Trinidad
A disturbed area of weather has developed 500 miles east of Trinidad and the southern Lesser Antilles Islands this afternoon. This disturbance is currently under an area of 10 - 15 knots of wind shear, but this shear is forecast to diminish the next several days. This may allow some slow development to occur as the disturbance tracks westward at 15 mph.

Hawaii
Flood watches are posted for all of the Hawaiian Islands as the moisture from Tropical Depression Kenneth moves over today. As yet, no heavy rains have impacted the islands.

Taiwan and China
Typhoon Langwang, a small but intense typhoon with 130 mph sustained winds, is headed towards a landfall on Taiwan Sunday. The upper-level outflow from the typhoon has degraded today, but there is no apparent wind shear affecting it, so landfall as a Category 3 storm is likely. Longwang is expected to weaken to a Category 1 storm after passage over the 10000 foot high mountains of Taiwan and continue on to strike mainland China on Monday.

Jeff Masters

TD 20 finally makes up its mind

By: JeffMasters, 3:13 PM GMT on October 01, 2005

Tropical Depression 20
The tropical disturbance in the western Caribbean Sea continues with its daily cycle of ups and downs, and finally hit enough of an "up" today to be classified as Tropical Depression 20. The amount of deep convection has increased to the highest level that we've seen yet, and now covers most of the western Caribbean Sea. An upper level outflow channel has opened to the north, and one can see high cirrus clouds streaming out to the north from the center of the depression. A few spiral bands have formed, and surface pressures continue to fall. The center of the depression is near buoy 42056 about 100 miles southeast of Cancun, Mexico. A hurricane hunter aircraft is on its way to investigate the system at 2 pm EDT afternoon.

The system is expected to cross the Yucatan Peninsula today and Sunday, so probably will not have time to strengthen into a tropical storm before then. Wind shear over the system is unchanged at 5 - 10 knots today, but after crossing the Yucatan, the shear is forecast to drop below 5 knots, and the system will have 36 hours or so to intensify over the warm 29 - 30C waters of the Gulf. I expect landfall as a Category 1 hurricane, or perhaps a strong tropical storm, on the Mexican coast south of Brownsville on Tuesday.

Hurricane Otis threatening Baja and Arizona
Hurricane Otis reached its peak intensity early this morning--a Category 2 hurricane with winds of 105 mph. Otis is expected to very slowly creep northwestward over cooler waters the next two days, and gradually weaken. By the time it takes a more northerly track and crosses the Baja Peninsula on Monday, Otis will probably be a strong tropical storm or weak Category 1 hurricane. Hurricane force winds extend outwards only 15 miles from Otis's center, so only a small portion of the coast will receive wind damage. Heavy rains of five inches or more will be the main problems with Otis, potentially triggering serious flash flooding in the desert mountains of Mexico--and by Tuesday, in Arizona.


Figure 2. Hurricane Otis.

TD 19
Tropical Depression 19 is far out over the Atlantic Ocean, about 600 miles west-southwest of the Cape Verdes Islands. The environment for strengthening is fair, and we will probably see this system become a tropical storm tonight. A hurricane seems unlikely, as this system is expected to move northwest or northward for the next five days into a region of increasing wind shear. It will be interesting to see if this storm or TD 20 wins the race to become Stan--loser gets the name Tammy.

Southeast U.S.
The global computer models are no longer forecasting tropical storm development near the Bahama Islands on Monday or Tuesday. Instead, they indicate that the favored genesis region may be the central or western Caribbean.

Hawaii
Flood watches are posted for all of the Hawaiian Islands as the moisture from Tropical Depression Kenneth moves over today. As yet, no heavy rains have impacted the islands.

Taiwan and China
Typhoon Langwang, a small but intense typhoon with 140 mph sustained winds, is headed towards a landfall on Taiwan Sunday. The upper-level outflow from the typhoon has degraded today, but there is no apparent wind shear affecting it, so landfall as a Category 3 or 4 storm is likely. Longwang is expected to weaken to a Category 1 storm after passage over the 10000 foot high mountains of Taiwan and continue on to strike mainland China on Monday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather