Category 6™

Category 2 Typhoon Krosa Hits the Philippines

By: JeffMasters, 2:55 PM GMT on October 31, 2013

Category 2 Typhoon Krosa is battering the northern end of Luzon, the main Philippines Island, after making landfall in extreme northeast Luzon near 06 UTC (2 am EDT) on October 31. Satellite loops show that Krosa's interaction with Luzon has weakened the storm, with the eye no longer visible, and the thunderstorms of the eyewall now warmer. The typhoon should be able to re-intensify once it emerges over the South China Sea on Friday, then weaken to Category 1 strength as it encounters higher wind shear and cooler waters before brushing China's Hainan Island on Sunday. According to the Joint Typhoon Warning Center (JTWC), Krosa's formation gives the Western Pacific 27 named storms so far in 2013, which is the average number of named storms for an entire year (the Japan Meteorological Agency named two additional storms this year, for a total of 29.) The last time there were more than 27 tropical storms or typhoons in the Western Pacific was in 2004, when there were 32. Krosa is the seventh typhoon of a very active October for typhoons in the Western Pacific. The Western Pacific is now up to an Accumulated Cyclone Energy level about 87% of average for the date, after a very slow first half of typhoon season. The Philippines are likely not through with typhoon season; for several days, the GFS model has been predicting that the islands will see two more named storms, with the first one (97W) passing through the central Philippines on Monday, and a second, potentially stronger storm, arriving on Thursday, November 7.


Figure 1. MODIS satellite image of Typhoon Krosa taken at approximately 02 UTC on October 31, 2013. At the time, Krosa was a Category 1 storm with winds of 90 mph. Image credit: NASA.

97E in Eastern Pacific will bring heavy rains to Mexico
In the Eastern Pacific, Invest 97E is spinning 350 miles southwest of Manzanillo, Mexico. Satellite loops show that 97E has a modest and increasing area of heavy thunderstorms that are growing more organized. In their 8 am EDT Tropical Weather Outlook, NHC gave 97E 2-day odds of development of 50%, and 5-day odds of 70%. 97E is moving north-northwest at 5 mph, and will likely move ashore on the Mexican coast near Mazatlan, due east of the tip of the Baja Peninsula, on Sunday night or Monday morning. Heavy rains from 97E will begin affecting the southern Baja Peninsula and portions of Mainland Mexico to its east beginning on Sunday morning. This moisture will spread northeastwards into Southwest Texas by Monday.

Quiet in the Atlantic
There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days. The European model is predicting that a large low pressure area will develop in the Central Caribbean late next week, but dry air and high wind shear may interfere with any development of this low. On Friday, I plan on posting a detailed outlook for the rest of the Atlantic hurricane season.

Jeff Masters

Hurricane

Five Things We Learned From Hurricane Sandy

By: JeffMasters, 2:28 PM GMT on October 29, 2013

1) Hurricane Sandy was truly astounding in its size and power. At its peak size, twenty hours before landfall, Sandy had tropical storm-force winds that covered an area nearly one-fifth the area of the contiguous United States. Sandy's area of ocean with twelve-foot seas peaked at 1.4 million square miles--nearly one-half the area of the contiguous United States, or 1% of Earth's total ocean area. Most incredibly, ten hours before landfall (9:30 am EDT October 29), the total energy of Sandy's winds of tropical storm-force and higher peaked at 329 terajoules--the highest value for any Atlantic hurricane since at least 1969, and equivalent to five Hiroshima-sized atomic bombs. At landfall, Sandy's tropical storm-force winds spanned 943 miles of the the U.S. coast. No hurricane on record has been larger. Sandy's huge size prompted high wind warnings to be posted from Chicago to Eastern Maine, and from Michigan's Upper Peninsula to Florida's Lake Okeechobee--an area home to 120 million people. Sandy's winds simultaneously caused damage to buildings on the shores of Lake Michigan at Indiana Dunes National Lake Shore, and toppled power lines in Nova Scotia, Canada--locations 1200 miles apart. Over 130 fatalities were reported and over 8.5 million customers lost power--the second largest weather-related power outage in U.S. history, behind the 10 million that lost power during the Blizzard of 1993. Damage from Sandy is estimated at $65 billion, making it the second most expensive weather-related disaster in world history, behind Hurricane Katrina of 2005.


Figure 1. Hurricane Sandy at 10:10 am EDT October 28, 2012. Image credit: NASA/GSFC.

2) NHC's procedures for issuing warnings need improvement. There was plenty of confusion on Sandy's storm surge risk. A post-Sandy federal review of the NWS’ performance found that the surge forecasts were remarkably accurate, but were not communicated in ways that made it easy for officials and the public to understand. NOAA has now set a target date of 2015 to implement explicit storm surge watches and warnings, something they have been working toward for several years. Experimental inundation graphics will come in 2014. It's critical that we do a better job with communicating storm surge risk; storm surge is the phenomenon that presents the greatest U.S. weather-related threat for a massive loss of life in a single day, and was responsible for the largest fraction of direct deaths attributed to Sandy.

Sandy was technically not a hurricane at landfall, it was a "post-tropical cyclone," and NHC opted to handle the warnings using "Hurricane-force wind warnings." Such technicalities are often lost on the public, causing concern that the public may have been under-warned--though there's no evidence that fewer people evacuated from Sandy because of this issue, according to Florida State University researcher Dr. Jay Baker. The NWS and NHC now have the option to keep hurricane and tropical storm watches and warnings in place for post-tropical cyclones to avoid such confusion in the future. TWC hurricane specialist Bryan Norcross had this to say in his Sandy 1-year anniversary blog post: The meteorologists don’t want to hear it, and I don’t like it either, but the truth is, the quality of the meteorology is so far ahead of the quality of threat communications in the U.S. that progress in forecasting is becoming less and less relevant. Andrew Freedman at Climate Central has a detailed look at the communication problems with Sandy's forecast.


Figure 2. Hurricane Sandy’s winds on October 28, 2012, when Sandy was a Category 1 hurricane with top winds of 75 mph (this ocean surface wind data is from a radar scatterometer on the Indian Space Research Organization’s (ISRO) Oceansat-2.) Image credit: NASA.

3) The European ECMWF weather forecast model is better than the U.S. GFS model. The superior performance of the European model for long-range forecasts of Sandy led for calls to improve computer model forecasts in the U.S. NOAA's National Center for Environmental Prediction has significantly upgraded the computer power used to make forecasts since Sandy, but it will be difficult for the U.S. to catch up to the Europeans, as wunderground's climate change blogger, Dr. Ricky Rood, explained in an article for the Washington Post.


Figure 3.The Battery Park Underpass during Hurricane Sandy, October 30, 2012 (top) and one year later (bottom, October 16, 2013.) Image credit: Natan Dvir/Polaris. An impressive set of 148 before-and-after Sandy photos taken from identical locations one year apart have been put together by TWC.

4) Arctic sea ice loss due to global warming may have made Sandy's unusual track more likely. Sandy took the most perpendicular track into the Northeast U.S. coast of any tropical cyclone in the historical record (Hall and Sobel, 2013.) Using historical climate data, these scientists estimated that the return period of a Category 1 or stronger storm hitting New Jersey at such an odd angle was 1-in-700-years. The 2012 Arctic sea ice melt season was extreme, with sea ice extent hitting an all-time record low just weeks before Sandy hit. Could sea ice loss have contributed to the blocking ridge that steered Sandy into New Jersey? A paper published in August 2013 in the Proceedings of the National Academy of Sciences by Elizabeth Barnes of Colorado State and co-authors, "Model projections of atmospheric steering of Sandy-like superstorms", argues that our best climate models project we should see a decrease in the type of steering patterns that brought Sandy to the coast at such an unusual angle. However, as I discussed in an April 2013 post, Arctic sea ice loss tied to unusual jet stream patterns, three studies published in the past year have found that the jet stream has been getting stuck in unusually strong blocking patterns in recent years. These studies found that the recent record decline in Arctic sea ice could be responsible, since this heats up the pole, altering the Equator-to-pole temperature difference, forcing the jet stream to slow down, meander, and get stuck in large loops. The author of one of the new studies, Dr. Jennifer Francis of Rutgers, had this say at Andy Revkin's Dot Earth blog: "While it’s impossible to say how this scenario might have unfolded if sea-ice had been as extensive as it was in the 1980s, the situation at hand is completely consistent with what I’d expect to see happen more often as a result of unabated warming and especially the amplification of that warming in the Arctic."


Figure 4. Tracks of all tropical storms and hurricanes to hit Southern New Jersey, 1851 - 2012. Hurricane Sandy had a track unprecedented in the historical record. Image created by TWC's Stu Ostro using data from NOAA/CSC.

5) There may be more storms like Sandy in the future. The Atlantic hurricane season is getting longer, and ocean temperatures are warming. This increases the odds that we will see more hurricanes in October making it far to north near New England, where they can potentially get entangled with extratropical fall storms. Furthermore, dangerous part-hurricane, part extratropical hybrid storms like Hurricane Sandy are expected to be an increasing threat for Western Europe by the end of the century due to global warming, said a team of scientists led by Reindert J. Haarsma of the Royal Netherlands Meteorological Institute. In a paper called "More hurricanes to hit Western Europe due to global warming", published in April 2013 in Geophysical Research Letters, the researchers described the results from runs of a high-resolution (25 km grid spacing) climate model based on the European Centre for Medium Range Weather Forecasts (ECMWF) numerical weather prediction model. The model predicts that the breeding ground for Atlantic hurricanes will shift approximately 700 miles eastwards as the oceans warm this century. Hurricanes which form farther to the east can spend more time over warm tropical waters before turning north and northeast towards Europe, increasing the odds that these storms will have hurricane-force winds upon arrival in Europe. The researchers concluded that "tropical cyclones will increase the probability of present-day extreme events over the North Sea and the Gulf of Biscay with a factor of 5 and 25 respectively, with far reaching consequences especially for coastal safety."

Sandy links
Colorful 2-D and 3-D model animations of Sandy from Bob Henson of UCAR.

Colorful 5-day animation of Sandy's winds from NASA (Scroll down to third video, 850 mb level.) 

Twelve strange weather features of Superstorm Sandy from Seth Borenstein of AP.

Scientific American has an interesting storm surge simulation video of the flooding of Hoboken, NJ, showing a highly detailed look at how the surge entered the city (2nd video on page.) Animations were sone from modeling by Philip Orton and colleagues at the Stevens Institute of Technology.

PBS' NOVA series did an excellent job looking at the aftermath of Sandy in the their 1-hour show, Megastorm Aftermath, which aired on October 8.


Video 1. ‪After Sandy: Changes and Choices‬. Video produced by the Climate.gov team in cooperation with climate and Earth scientists from the National Oceanic and Atmospheric Administration and other agencies and institutions.

Later today, wunderground's weather historian Christopher C. Burt will have the latest figures from the destructive storm named "Christian" that hit Northern Europe, in his blog. According to Dr. Michael Theusner of the German climate museum Klimahaus, a wind gust of 119 mph (191 kph) was recorded on the island of Heligoland, Germany by the weather station of Germany’s biggest private weather company. If verified, this would be the highest wind gust ever recorded at low elevation in Germany. 

I'll have a new post by Thursday.


Jeff Masters

Hurricane

Powerful St. Jude's Day Storm Pounding France and the UK

By: JeffMasters, 2:57 AM GMT on October 28, 2013

A mighty Atlantic gale, called the 2013 St. Jude's Day storm by the UK Met Office, and "Christian" by the Free University of Berlin, is battering Western Europe with hurricane-strength wind gusts, waves up to 25 feet high, and driving rains. As of 2 am local time, the peak wind gust from the storm in the UK according to a tweet from the UK Met Office (@metoffice) was 92 mph, at the Isle of Wight in the English Channel. Powerful winds have also swept the north coast of France; winds in Brest, France hit 41 mph, gusting to 67 mph at 2 am local time Monday, and gusted as high as 65 mph at Caen. With the trees still in leaf, winds this strong have the potential to cause heavy tree damage and large scale power outages. The storm is moving quickly, and sustained winds fo 35 - 45 mph will arrive along the coast of the Netherlands by 6 am local time Monday, by noon in Denmark, near 6 pm in Southern Sweden, and near midnight Monday night in Estonia and Southern Finland. You can check out the current winds in Southern Britain and Northern France using our wundermap zoomed into the region with the weather station layer turned on.


Figure 1. Waves crash against the sea barriers in Porthcawl, South Wales, on October 27, 2013, ahead of the arrival of the St. Jude's Day storm. Image credit: GEOFF CADDICK/AFP/Getty Images.

Last majorly destructive extratropical storm in Western Europe: 2011
October 28 is St. Jude's feast day, in honor of the Catholic saint who was one of Jesus' twelve apostles and is often appealed to as the patron saint of lost causes. His namesake storm has the potential to be one of the more destructive extratropical storms to hit Western Europe in the past decade, judging by a short history of these storms written by wunderground's weather historian Christopher C. Burt back in 2011. The most recent storm of note to hit the region was Winter Storm Joachim of December 15 - 17, 2011, which has a central pressure of 964 mb and brought a peak wind gust of 131 mph to Auvergne, France. Damage was estimated at $325 million by Aon Benfield. Also in that year, ex-Hurricane Katia hit northern Scotland on September 12 when the trees were in full leaf, causing tree damage that was much higher than a winter or springtime storm of similar ferocity would have caused. One person was killed by a falling tree, and heavy tree damage and numerous power failures were reported throughout Britain, with a price tag of $158 million, according to Aon Benfield. Wind gusts experienced in Britain included 86 mph at Glen Ogle, Scotland, 76 mph at Edinburgh Blackford Hill, 75 mph at Capel Curig in Wales, 72 mph at Glasgow Bishopton, and 71 mph at Loftus, North Yorkshire.


Figure 2. Image of Hurricane Katia taken from the International Space Station at 15 GMT September 9, 2011, by astronaut Ron Garan. At the time, Katia was a Category 1 hurricane with 85 mph winds. Long Island, New York is visible at the lower left.

I'll have a new post by Tuesday morning.

Jeff Masters

Winter Weather

Earth's 4th Warmest September on Record; 32 Billion-Dollar Disasters so far in 2013

By: JeffMasters, 2:26 PM GMT on October 25, 2013

September 2013 was the globe's 4th warmest September since records began in 1880, according to NOAA's National Climatic Data Center (NCDC). The year-to-date period of January - September has been the 6th warmest such period on record. September 2013 global land temperatures were the 6th warmest on record, and global ocean temperatures were the 4th warmest on record. September 2013 was the 343nd consecutive month with global temperatures warmer than the 20th century average. Global satellite-measured temperatures in September 2013 for the lowest 8 km of the atmosphere were 11th or 3rd warmest in the 35-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH), respectively. Wunderground's weather historian, Christopher C. Burt, has a comprehensive post on the notable weather events of September 2013 in his September 2013 Global Weather Extremes Summary.


Figure 1. Departure of temperature from average for September 2013, the 4th warmest September for the globe since record keeping began in 1880. Record warmth was observed across most of Australia and part of central Asia, as well as part of southwestern Canada. Most of central and northern North America, northern Europe, and much of central and southern Asia were much warmer than average. Cooler and much-cooler-than-average temperatures occurred across much of central and eastern Russia, along with most of eastern Europe and western Greenland. Image credit: National Climatic Data Center (NCDC) .

The five billion-dollar weather disasters of September 2013
Five billion-dollar weather-related disasters hit the Earth during September 2013, bringing the world-wide tally of these disasters so far in 2013 to 32, according to the September 2013 Catastrophe Report from insurance broker Aon Benfield. This is the third highest yearly total for the globe since accurate disaster records began in 2000, according to Senior Scientist Steve Bowen of Aon Benfield. The record highest was 40 billion-dollar disasters in 2010. For comparison, during all of 2012, there were 27 billion-dollar weather disasters; the tally in 2011 was 35 (adjusted for inflation.) The U.S. total so far in 2013 is seven.




Disaster 1. The most damaging billion-dollar weather disaster of September was in Mexico, where Hurricane Manuel made two landfalls along Mexico's Pacific coast. Flooding from Manuel's torrential rains caused $4.2 billion in damage and left 169 people dead or missing. According to EM-DAT, the International Disaster Database, this was the second most expensive weather-related disaster in Mexican history, behind the $6 billion in damage (2013 dollars) wrought by Hurricane Wilma in October 2005. In this aerial view, we see the landslide triggered by Hurricane Manuel's rains that killed 43 people in La Pintada, México, on September 19, 2013. (Pedro Pardo/AFP/Getty)


Disaster 2. Super Typhoon Usagi made landfall near Shanwei, China on September 22, 2013 as a Category 2 typhoon with 110 mph winds, after skirting the Philippines and Tawian. The storm killed at least 37 people and did $3.8 billion in damage. Property damage was widespread in five Chinese provinces as Usagi damaged at least 101,200 homes. This radar image of Usagi shows that the typhoon had multiple concentric eyewalls as it approached landfall. Image credit: weather.com.cn.


Disaster 3. Record rainfall of 8 - 15" triggered historic flash flooding across in Colorado September 11 - 12, 2013, killing at least nine people and doing $2 billion in damage. The most significant damage occurred in Boulder, Larimer and El Paso counties after several major rivers and creeks crested at all-time highs. The Office of Emergency Management reported that nearly 20,000 homes were damaged or destroyed in addition to thousands of businesses and other structures. One person was also killed by flooding in New Mexico. In this image, we see damage to Highway 34 along the Big Thompson River, on the road to Estes Park, Colorado. Image credit: Colorado National Guard.


Disaster 4. Category 1 Hurricane Ingrid weakened to a tropical storm with 65 mph winds before hitting Mexico about 200 miles south of the Texas border on September 16, 2013. Ingrid's heavy rains triggered flooding that killed 23 and did $1.5 billion in damage, making the storm the 7th costliest tropical cyclone in Mexican history. In this image, we see Tropical Storm Manuel and Hurricane Ingrid laying siege to Mexico on September 15, 2013. Tropical Storm Manuel came ashore on the Pacific coast near Manzanillo on the afternoon of September 15, and Ingrid followed suit from the Atlantic on September 16. Image credit: NASA Earth Observatory.


Disaster 5. A series of killing freezes during the second half of September led to extensive agricultural damage in central Chile. A state of emergency was declared after farmers reported that frigid air had destroyed 61% of stoned fruit crops, 57% of almonds, 48% of kiwi crops, and 20% of table grapes. Heavy damage to vineyards also affected wine productivity. Total damage was estimated at $1.15 billion.

Neutral El Niño conditions continue in the equatorial Pacific
For the 18th month in row, September 2013 featured neutral El Niño conditions in the equatorial Eastern Pacific. NOAA's Climate Prediction Center (CPC) expects neutral El Niño conditions to last the Northern Hemisphere spring of 2014, as do the large majority of the El Niño models. Temperatures in the equatorial Eastern Pacific need to be 0.5°C below average or cooler for three consecutive months for a La Niña episode to be declared; sea surface temperatures were 0.4°C below average as of October 21, and have been +0.1 to -0.4°C from average since April 1, 2013.

Arctic sea ice falls to 6th lowest September extent on record
Arctic sea ice extent during September was 6th lowest in the 35-year satellite record, according to the National Snow and Ice Data Center (NSIDC). This was the largest September extent since 2009, and a nice change of pace from last year's all-time record retreat. The Arctic sea ice reached its minimum extent for the year on September 13, and has now begun re-freezing.

New "Tipping Points" episode, "Dangerous Rise of Oceans", airs Saturday at 9 pm EDT/8 pm CDT
“Tipping Points”, a landmark 6-part TV series that began last Saturday on The Weather Channel, airs for the second time on Saturday night, October 26, at 9 pm EDT. The new episode, "Dangerous Rise of Oceans", goes on an expedition from the Great Southern Ocean to the Great Barrier Reef and Tuvalu, to explore the changing currents and oceans that are driving extreme storms, sea surge and changing the landscape of many small South Pacific communities. The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to climb Mt. Everest and walk to the North and South Poles. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point--a point of no return when our climate system will be changed irreversibly.


Figure 2. "Tipping Points" host Bernice Notenboom visits the Heron Island Research Station on Australia's Great Barrier Reef during Saturday's new episode, "Dangerous Rise of Oceans."

I'll be back with a new blog post on Monday. Have a great weekend, everyone!

Jeff Masters

Climate Summaries

Australia Endures Another Dangerous Fire Weather Day; Lorenzo Dissipates

By: JeffMasters, 3:23 PM GMT on October 24, 2013

Sydney, Australia and the Blue Mountains have endured a second day of dangerous fire weather conditions without a devastating fire catastrophe ensuing. The high temperature in Sydney on Thursday hit 73°F, with sustained winds of 30 mph gusting to 41 mph, and a humidity as low as 7%. The temperature was nearly 20°F cooler than on Wednesday, but the strong winds and low humidity helped fan the 56 fires still burning across the state of New South Wales. Tragically, a fire-fighting aircraft crashed Thursday during a mission to douse one of the fires, killing the pilot and starting a new fire. The fires have burned more than 120,000 hectares (300,000 acres), and have a perimeter of about 1,600 km (990 miles), and are being blamed for two deaths and over $97 million in damage. Australia has just had its hottest September on record, and the 12-month period ending in August 2013 set a record for the hottest 12-month period in Australian history. Australia's warmest summer and 3rd warmest winter on record occurred during this 12-month period. It has also been quite dry in the fire region over the past few months, with sol moisture levels in the lowest 10% historically. However, the latest drought statement from the Bureau of Meteorology is not showing that long-term drought conditions exist.


Figure 1. Volunteer Christelle Gilmore cares for 'Phoenix', an orphaned baby Swamp Wallaby burned in the Springwood fires on October 22, 2013 in Castlereagh, Australia. Photo by Brendon Thorne/Getty Images.

Raymond weakens, moves away from Mexico
Tropical Storm Raymond continues to move away from the coast of Mexico, and will no longer bring heavy rains to the country. Recent satellite loops show that Raymond is a poorly-organized tropical storm, with just a modest area of heavy thunderstorms.


Figure 2. Rainfall over Mexico from October 15 - 23 from Hurricane Raymond totaled close to 10" near Acapulco, as estimated by NASA's TRMM satellite. Fortunately, Raymond did not move ashore, or else the 15+" inches of rain that fell offshore would have fallen over land. Image credit: NASA Goddard Space Flight Center.

Tropical Storm Lorenzo dies in the Middle Atlantic
Tropical Storm Lorenzo has died in the Middle Atlantic, done in by high wind shear. None of the reliable computer models for tropical cyclone genesis are predicting any new storms developing in the coming five days. During the first week of November, the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, will bring rising air over the Caribbean, increasing the odds of a tropical storm developing then.

Typhoons Francisco and Lekima weaken
Typhoon Francisco has weakened to a tropical storm, and is bringing heavy rains to Japan as it stays offshore and heads northeast, parallel to the coast. Super Typhoon Lekima, which stayed at Category 5 status for a day and a half, has now weakened to a Category 4 storm with 150 mph winds. Satellite loops show that Lekima is still an impressive typhoon with a prominent eye surrounded by a solid ring of eyewall clouds with very cold cloud tops. Lekima is predicted to recurve to the northeast without affecting any land areas. While Lekima was at peak strength between 12 and 18 UTC on Wednesday, its eye expanded greatly in size while the storm stayed at Category 5 strength, something that is very unusual to see (thanks to Scott Bachmeier of the University of Wisconsin CIMSS for the info and animation.)


Figure 3. MODIS satellite image of Super Typhoon Lekima, taken at approximately 01:05 UTC on October 24, 2013. At the time, Lekima was a Category 5 super typhoon with winds of 160 mph. Image credit: NASA.

Jeff Masters

Fire Hurricane

Australia Avoids a Fire Catastrophe; Raymond Spares Mexico; Lekima a Cat 5

By: JeffMasters, 2:26 PM GMT on October 23, 2013

Sydney, Australia and the Blue Mountains to its west endured extreme fire weather conditions on Wednesday without catastrophe, as "aggressive" and "high-risk" fire fighting strategies kept the 71 fires burning in New South Wales from causing major devastation. "The broader risk to a much larger, more widespread population has certainly eased," said Shane Fitzsimmons, a fire official for the region. The fire conditions in the region were about as bad as it gets on Wednesday. The high temperature in Sydney hit 92°F, with sustained winds of 34 mph gusting to 47 mph, and a humidity as low as 4%. Temperatures are expected to be cooler on Thursday, but westerly winds blowing from the dry interior of Australia will still be blowing strongly, keeping fire danger extreme. Insurance claims from the huge fires that have ravaged areas just west of Sydney over the past week are already set to exceed $97 million (U.S. dollars), according to The Insurance Council of Australia, even though the worst-hit areas have not been assessed yet. This price tag already makes the disaster Australia's fifth most expensive fire on record, according to EM-DAT, the international disaster database. Wunderground's weather historian Christopher C. Burt has a new post on the history of Australian wild fires.


Figure 1. Smoke from fires burning over Southeast Australia streams out over the ocean near Sydney, Australia, due to strong westerly winds. MODIS photo taken at 03:15 UTC on October 23, 2013. Image credit: NASA

Fires worsened by Australia's hottest September on record
Australia has just had its hottest September on record, and the 12-month period ending in September 2013 set a record for the hottest 12-month period in Australian history. Australia's warmest summer and 3rd warmest winter on record occurred during this 12-month period. It has also been quite dry in the fire region over the past few months, with soil moisture levels in the lowest 10% historically for this time of year. However, the latest drought statement from the Bureau of Meteorology is not showing that long-term drought conditions exist.


Figure 2. Running means for the departure of temperature from average (the anomaly) for Australia for 12-month periods ending 31 August 2013. Vertical grid lines mark 12-month periods commencing January 1920, January 1930, etc. Australian temperatures are now, on average, more than 1°C warmer than during the 1950s. Image credit: Australian Bureau of Meteorology.

Climate Change and Australian fires
“Climate change is increasing the risk of more frequent and longer heat waves and more extreme hot days, as well as exacerbating bushfire conditions.” So said the independent non-profit Australia Climate Council in a report on the record September 2013 heat in Australia. In April 2013, the group (then called the Australia Climate Commission) published a report, "The Critical Decade: Extreme Weather", which gave an excellent overview of climate change and wild fires in Australia. According to the report, " many regions have already experienced an increase in extreme fire weather as indicated by changes in the Forest Fire Danger Index (FFDI). The main contributors to this increase are prolonged periods of low rainfall and the increased frequency and intensity of extreme heat. The FFDI increased significantly at 16 of 38 weather stations across Australia between 1973 and 2010, with none of the stations recording a significant decrease. The increase has been most prominent in southeast Australia, and has been manifest as a longer duration fire season, with fire weather extending into November and March. The opportunity for fuel reduction burning is reducing as fire seasons have become longer. Overall, this means that fire prone conditions and vulnerability to fire are increasing. The projected increases in hot days across the country, and in consecutive dry days and droughts in the southwest and southeast, will very likely lead to increased frequencies of days with extreme fire danger in those regions."

Australia's Climate Commission was defunded after the new government led by Prime Minister Tony Abbott took power in September 2013, writes Brian Kahn at climatecentral.org. However, the commissioners banded together and used crowd-funding to raise $1 million to start the non-profit Climate Council, a nonprofit organization aimed at providing climate information on Australia to the public. The Council is planning to release a report specifically about wildfires in November 2013. Australian Prime Minister Tony Abbott, who is a volunteer fire fighter, and famously said in 2009 that the science behind climate change is “absolute crap”. On Wednesday, he remarked: "Climate change is real, as I've often said, and we should take strong action against it. "But these fires are certainly not a function of climate change--they're just a function of life in Australia."

Raymond weakens to a tropical storm; threat diminishes for Mexico
Tropical Storm Raymond continues to spin just offshore of Acapulco, Mexico, but its top winds have weakened to 65 mph. As of 8 am EDT Wednesday, Raymond was stationary, and centered about 190 miles west-southwest of Acapulco. Raymond brought 7.05" of rain Saturday through Tuesday to Acapulco. All watches and warnings have been discontinued for the coast of Mexico, but Raymond is expected to bring an additional 1 - 2" of rain to the coast. Raymond is in an area with weak steering currents, but a ridge of high pressure is forecast to build in later Wednesday and force the storm west-southwestwards, away from the coast. Recent satellite loops show the weakening trend of Raymond, and wunderblogger Lee Grenci has a new post discussing the causes.


Figure 3. MODIS satellite image of Hurricane Raymond, taken at approximately 2:30 pm EDT on October 22, 2013. At the time, Raymond was a Category 1 hurricane with winds of 75 mph. Image credit: NASA.

Tropical Storm Lorenzo in the Atlantic no threat
Tropical Storm Lorenzo continue to head eastwards into the Middle Atlantic, and will not be a threat to any land areas. Satellite loops show that Lorenzo has a small area of heavy thunderstorms, which are being pushed to the southeast side of Lorenzo's center of circulation by strong upper-level winds out of the northwest that are creating high levels of wind shear. The shear is forecast to remain in the high range through Friday, which will likely destroy the storm by then.

Typhoon Francisco weakening, but will still bring heavy rain to Japan
Typhoon Francisco continues to weaken, due to cool waters and increasing wind shear, and is now a Category 1 storm with 80 mph winds. Francisco is traversing a large cool patch of ocean left behind by the churning action of Typhoon Wipha last week. Francisco will make its closest approach to Japan on Thursday and Friday, and will likely be a tropical storm undergoing transition to an extratropical storm. Although the latest computer model guidance keeps Francisco well offshore from Japan, the storm will still bring plenty of tropical moisture over Japan, which will be capable of causing mostly minor flooding problems.

Super Typhoon Lekima reaches Category 5 strength
The Western Pacific has made up for a slow start to its typhoon season, and has now cranked out its third Category 5 super typhoon of the year. Super Typhoon Lekima intensified to Category 5 status about 1,500 miles southeast of Japan at 18 UTC on Tuesday, joining Super Typhoon Francisco, Super Typhoon Usagi, and Tropical Cyclone Phailin as the four members of 2013's Category 5 club. Four Cat 5s is a fairly typical number of these top-end storms for Earth to experience in one year. Satellite loops show an impressive typhoon with a prominent eye surrounded by a solid ring of eyewall clouds with very cold cloud tops. Lekima is predicted to recurve to the northeast without affecting any land areas.


Figure 4. MODIS satellite image of Typhoon Francisco (left) and Super Typhoon Lekima (right), taken at approximately 02 UTC on October 23, 2013. At the time, Lekima was a Category 5 super typhoon with winds of 160 mph, and Typhoon Francisco was at Category 1 strength with 80 mph winds. Image credit: NASA.

Jeff Masters

Fire Hurricane

As Bad as it Gets: Fire Conditions in Australia; Raymond Weakens, Deluging Mexico

By: JeffMasters, 3:21 PM GMT on October 22, 2013

Sydney, Australia and the Blue Mountains to its west are bracing for weather conditions that will bring extreme fire danger, with temperatures on Wednesday that are expected to be in the upper 80s, humidities less than 10%, and sustained winds of 15 -25 mph, gusting to 40 mph. These conditions will be "about as bad as it gets", said Shane Fitzsimmons, a fire official for the region. Insurance claims from the huge fires that have ravaged areas just west of Sydney over the past week are already set to exceed $97 million (U.S. dollars), according to The Insurance Council of Australia, even though the worst-hit areas have not been assessed yet. This price tag already makes the disaster Australia's fifth most expensive fire on record, according to EM-DAT, the international disaster database. Australia's just had its hottest September on record, and the 12-month period ending in August 2013 set a record for the hottest 12-month period in Australian history. Australia's warmest summer and 3rd warmest winter on record occurred during this 12-month period.

Wunderground's weather historian Christopher C. Burt has a new post on the history of Australian wild fires. The most expensive and deadly fires in Australian history occurred on Black Saturday, February 7, 2009. Those fires killed 173 people, injured 414, and destroyed 2,029 homes, causing $1.3 billion in damage.

Wunderground member AussieStorm posted this link to a photoalbum of fire pictures taken by residents of the Sydney area.


Figure 1. On October 21, 2013, dozens of wildfires continued to burn in New South Wales, Australia. The fires had already destroyed more than 200 homes, and Australian authorities were concerned that hot, windy weather could exacerbate the situation. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this image at 2:25 p.m. local time (3:25 Universal Time) on October 21. Red outlines indicate hot spots where MODIS detected unusually warm surface temperatures associated with fire.The largest fire shown here is the State Mine fire, which was burning in the Blue Mountains. The fire had burned more than 42,750 hectares, according to the New South Wales Rural Fire Service. Image credit: NASA Earth Observatory.

Hurricane Raymond weakens, but still drenching Mexico
Hurricane Raymond continues to spin just offshore of Acapulco, Mexico, as a Category 2 hurricane with 105 mph winds. As of 11 am EDT Tuesday, Raymond was stationary, centered about 135 miles west-southwest of Acapulco. Raymond brought 5.67" of rain Saturday through Monday to Acapulco, where a Hurricane Watch is posted. Raymond is expected to bring heavy rains of up to 12" to the coast, and this is an area where heavy rains are definitely most unwelcome. Hurricane Manuel hit this region of Mexico with extreme torrential rains when it made landfall on September 15, triggering deadly mudslides and flooding that left 169 people dead or missing and caused $4.2 billion in damage. According to EM-DAT, the International Disaster Database, this was the second most expensive weather-related disaster in Mexican history, behind the $6 billion in damage (2013 dollars) wrought by Hurricane Wilma in October 2005.

Raymond is in an area with weak steering currents, and is likely to show some erratic movement until Wednesday, when a ridge of high pressure is forecast to build in and force the storm west-southwestwards, away from the coast. Recent satellite loops show a weakening trend, as the southeast eyewall is now missing, and the storm's heavy thunderstorms have diminished in intensity. This weakening may be due to the colder waters from below that Raymond's winds have churned to the surface. An Air Force hurricane hunter aircraft will investigate Raymond on Tuesday afternoon.

Wunderblogger Lee Grenci has a detailed look at the ocean temperatures and steering flow affecting Raymond.


Figure 2. MODIS satellite image of Hurricane Raymond, taken at 3:30 pm EDT on October 21, 2013. At the time, Raymond was at peak strength, a Category 3 storm with winds of 125 mph. Image credit: NASA.

Tropical Storm Lorenzo forms in the Middle Atlantic
The 12th Atlantic named storm of 2013, Tropical Storm Lorenzo, was born on Monday afternoon. Lorenzo's formation brings this year's Atlantic tally to 12 named storms, which is one more than the long term average. However, Lorenzo is going to be one of those weak, short-lived tropical storms that likely would have been missed before satellites came along in the 1960s. There have been three other weak, short-lived tropical storms in 2013 that stayed far out to sea that may have been missed before satellites came along--Dorian, Erin, and Jerry. There has been a large increase in the number of "shorties"--Atlantic tropical storms lasting two days or less--since the 1950s, as discussed by Villarini et al. (2011), in their paper, Is the recorded increase in short‐duration North Atlantic tropical storms spurious?

Satellite loops show that Lorenzo has a modest area of heavy thunderstorms, which are pushed to the east side of Lorenzo's center of circulation by strong upper-level winds out of the southwest. Wind shear is moderate, 15 - 20 knots, but is expected to increase to the high range by Tuesday night, giving Lorenzo a rather short life. The storm will not be a threat to any land areas.


Figure 3. Latest satellite image of Lorenzo.

Typhoon Francisco weakening, likely to miss Japan
Typhoon Francisco has steadily weakened since becoming Earth's third Category 5 storm of 2013 on Saturday, and is now a Category 1 storm with 85 mph winds. Francisco is now traversing a large cool patch of ocean up to 2°C colder than the surrounding waters, left behind by the churning action of Typhoon Wipha last week. By the time Francisco makes its closest approach to Japan on Thursday and Friday, it will be a tropical storm undergoing transition to an extratropical storm. However, the latest computer model guidance keeps Francisco well offshore from Japan, and the storm's heaviest rains will miss the country. This is good news for Japan, which is still cleaning up from the record rains that Typhoon Wipha brought last week.

Impressive Typhoon Lekima hits Category 4 strength
The Western Pacific has made up for a slow start to its typhoon season, and has now cranked out its fifth major Category 3 or stronger typhoon of the month. Typhoon Lekima is an impressive Category 4 typhoon with 145 mph winds, intensifying over the warm waters of the Western Pacific about 1,500 miles southeast of Japan. Satellite loops show that Lekima is another very well-organized typhoon with a prominent eye surrounded by a solid ring of eyewall clouds with very cold cloud tops. Lekima is predicted to reach Category 5 strength on Thursday, but will likely recurve to the northeast without affecting any land areas.


Figure 4. MODIS satellite image of Typhoon Francisco (left) and Typhoon Lekima (right), taken at approximately 02 UTC on October 22, 2013. At the time, both typhoons had top winds near 85 mph. Image credit: NASA.

One year ago today: Tropical Depression Eighteen forms
One year ago today, here is what I wrote in my blog post, Tropical Depression 18 forms south of Jamaica: "Tropical Depression Eighteen is here, and appears poised to become Tropical Storm Sandy by early Tuesday morning. TD 18 is over very warm waters of 29.5°C, is in a moist environment, and has light wind shear of 5 - 10 knots. These conditions are very favorable for intensification, and TD 18's heavy thunderstorms are steadily organizing into curved spiral bands….It is unclear at this point whether or not the trough pulling TD 18 to the north will be strong enough to pull the storm all the way out to sea to the northeast; a very complicated steering environment will develop late this week, and it is possible that a narrow ridge of high pressure could build in over TD 18 and force the storm to the west-northwest, with a potential threat to the Northwestern Bahamas and U.S. East Coast by Saturday, as predicted by the ECMWF model."


Figure 5. Morning satellite image of Tropical Depression Eighteen on October 22, 2012.

Jeff Masters

Fire Hurricane

Category 3 Raymond Drenching Acapulco; TD 13 Forms; Extreme Air Pollution in China

By: JeffMasters, 1:22 PM GMT on October 21, 2013

Hurricane Raymond roared into life on Sunday just offshore from Acapulco, Mexico, rapidly intensifying from a minimal-strength tropical storm with 40 mph winds to a major Category 3 hurricane in just 24 hours. Raymond is the first major hurricane in the Eastern Pacific in 2013, making it the first year since 1968 that both the Eastern Pacific and Atlantic had made it into October without a major hurricane. Raymond has brought more than 3" of rain so far to Acapulco, where a Hurricane Watch is posted. As of 8 am EDT, Raymond was drifting slowly northwards at 2 mph toward Mexico, and was centered about 165 miles west-southwest of Acapulco. Raymond is expected to bring heavy rains of up to 8" to the coast, and this is an area where heavy rains are definitely most unwelcome. Hurricane Manuel hit this region of Mexico with extreme torrential rains when it made landfall on September 15, triggering deadly mudslides and flooding that left 169 people dead or missing and caused $4.2 billion in damage. According to EM-DAT, the International Disaster Database, this was the second most expensive weather-related disaster in Mexican history, behind the $6 billion in damage (2013 dollars) wrought by Hurricane Wilma in October 2005.

Raymond is in an area with weak steering currents, and is likely to show some erratic movement until Wednesday, when a ridge of high pressure is forecast to build in and force the storm westwards, away form the coast. Given Raymond's very slow movement, the storm may weaken later today and on Tuesday, as it stirs up colder water from below. However, there is no evidence of weakening on the latest satellite loops, which show a well-organized hurricane with a prominent eye and impressive-looking eyewall clouds with cold tops that reach high into the atmosphere.

Wunderblogger Lee Grenci has a detailed look at the ocean temperatures and steering flow affecting Raymond.


Figure 1. Aerial view of the landslide triggered by Hurricane Manuel's rains, which killed 43 people in La Pintada, México, on September 19, 2013. (Pedro Pardo/AFP/Getty)

TD 13 forms in the Middle Atlantic
Tropical Depression Thirteen has formed from an area of disturbed weather located about 650 miles east-southeast of Bermuda. Satellite loops show TD 13 has a moderate area of heavy thunderstorms and solid low-level spin. An ASCAT pass from 1:22 UTC Monday morning showed a closed surface circulation, and top winds of 30 - 40 mph on the storm's east side. Wind shear is moderate, 10 - 15 knots, but is expected to increase to the high range by Tuesday night, giving TD 13 a short window in which to develop. If it does intensify, it will become Tropical Storm Lorenzo. TD 13 will not be a threat to any land areas.


Figure 2. MODIS satellite image of Tropical Depression 13, taken at approximately 12:30 pm EDT October 21, 2013. At the time, TD 13 had top winds of 35 mph. Image credit: NASA.

Typhoon Francisco headed towards Japan
Category 2 Typhoon Francisco has steadily weakened on Sunday and Monday, after spending just over a day as Earth's third Category 5 storm of 2013 on Saturday. Satellite loops show a large, cloud-filled eye and a decaying eyewall. Since wind shear remains low, the weakening is likely in response to cooler ocean temperatures, since Francisco is now traversing a large cool patch of ocean up to 2°C colder than the surrounding waters, left behind by the churning action of Typhoon Wipha last week. By the time Francisco makes its closest approach to Japan on Thursday and Friday, it will be undergoing transition to an extratropical storm. Francisco's interaction with a cold front over Japan during this process will bring very heavy rains to Japan, and these rains will pose a serious flooding threat, as the soils have not had a chance to dry out much from the record rains that Typhoon Wipha brought last week. The 00Z Monday run of the HWRF model predicted a large swath of 4 - 8 inches of rain for Japan from Francisco. The University of Wisconsin CIMSS Satellite Blog has some impressive images of Francisco from when it was a Super Typhoon.


Figure 3. Infrared satellite image of Super Typhoon Francisco, taken at 15:48 UTC on October 18, 2013. At the time, Francisco was a high-end Category 4 storm with top winds of 155 mph. Image credit: University of Wisconsin CIMSS Satellite Blog.

China's 10th-largest city shuts down because of extreme air pollution
Harbin, China, the nation's 10th most populous city with a population of 11 million, has virtually shut down today because of extreme levels of air pollution reaching up to 1,000 micrograms per cubic meter. The safe level recommended by the World Heath Organization (WHO) is just 25 micrograms per cubic meter. The dense pollution was created by stagnant air on a day when the city's heating systems kicked in for the first time this fall. With visibility less than 50 yards, the airport was forced to close, as well as most schools and some roads. Cir.ca has some remarkable images of the event, and here is zoomable map of real-time Chinese air quality.


Figure 4. A woman walks along a road as extreme air pollution engulfs the city on October 21, 2013 in Harbin, China. ChinaFotoPress/Getty Images


Video 1. Extreme air pollution in Harbin, China on October 21, 2013. Thanks go to wunderground member Patrap for alerting me to this video.

Jeff Masters

Hurricane Air and Water Pollution

Super Typhoon Francisco Becomes Earth's 3rd Category 5 Storm of 2013

By: JeffMasters, 5:02 PM GMT on October 19, 2013

Mighty Super Typhoon Francisco has intensified to become Earth's third Category 5 storm of 2013. The other two Cat 5s were Cyclone Phailin, which hit India earlier this month at Category 3 or 4 strength, killing 44 and causing at least $1 billion in damage, and Super Typhoon Usagi, which hit China just east of Hong Kong as a Category 2 storm on September 22, killing 50 and causing at least $3.8 billion in damage. Satellite loops show a spectacular, well-organized storm with an impressive area of heavy thunderstorms and a prominent eye. With warm waters that extend to great depth and low wind shear, Francisco is likely to stay at Category 5 strength until an eyewall replacement cycle begins. Francisco is headed northwest towards Japan, and will likely stay at Category 4 or stronger intensity until Tuesday, when the storm will encounter higher wind shear and cooler waters. By the time Franciso makes its closest approach to Japan on Thursday, weakening to Category 2 or lesser strength is likely. In their Saturday morning runs, both the European model and GFS model predicted that Francisco would turn northeastwards on Wednesday, and hit Japan on Thursday. There is very high uncertainty in the storm's track that far into the future, though, since the timing of Francisco's turn the northeast is difficult to predict.


Figure 1. MODIS satellite image of Typhoon Francisco, taken at approximately 03 UTC on October 19, 2013. At the time, Francisco was a Category 5 storm with top winds of 160 mph. Image credit: NASA.

The Atlantic is quiet
None of the reliable computer models for forecasting tropical cyclone genesis is predicting development over the next five days.

Intriguing Tipping Points TV Series Begins Airing Saturday at 9pm EDT
How does one tell the most important story of our time--the emergence of our great Climate Disruption--without boring one's audience to tears, but at the same time, not resorting to over-hyped spinning of the science? “Tipping Points”, a landmark 6-part TV series that begins airing at 9 pm EDT Saturday, October 19 on The Weather Channel, aims to do just that. "Tipping Points" follows a group of preeminent scientists as they venture off the grid to explore the perilous tipping points making our weather systems more extreme and unpredictable. The first episode at 9 pm EDT/8 pm CDT this Saturday will be "Amazon Rainforest Risks". "Tipping Points" host Bernice Notenboom will join Peter Cox, Professor of Climate System Dynamics at the University of Exeter, on an expedition across the vast Amazon Rainforest to explore the mega droughts and tree deaths occurring that threaten the forest's survival this century.



Have a great weekend, everyone, and I'll be back Monday with a new post.

Jeff Masters

Hurricane

Intriguing Tipping Points TV Series Begins Airing Saturday at 9pm EDT

By: JeffMasters, 12:09 PM GMT on October 18, 2013

How does one tell the most important story of our time--the emergence of our great Climate Disruption--without boring one's audience to tears, but at the same time, not resorting to over-hyped spinning of the science? “Tipping Points”, a landmark 6-part TV series that begins airing at 9 pm EDT Saturday, October 19 on The Weather Channel, aims to do just that. "Tipping Points" follows a group of preeminent scientists as they venture off the grid to explore the perilous tipping points making our weather systems more extreme and unpredictable.

The phenomena of “tipping points” follows the concept that, at a particular moment in time, a small change can have a large, long-term consequence on a fragile climate system already in a state of flux. Localized ecological systems are known to shift abruptly and irreversibly from one state to another when they are forced across critical thresholds. Further, when the situation is pushed past the “tipping point,” it will potentially lead to a chain reaction, putting other ecosystems around the globe in peril. “Tipping Points” will feature several of the most critical examples, including the collapse of the Greenland ice sheet, total melting of the Himalayan icecap glaciers, die-back of the Amazon rainforest, shutdown of the Atlantic Thermohaline Circulation, and the rapid melt of the permafrost in Siberia. "Tipping Points" will not only show how climate changes affect local communities in exotic and distant locales like the Amazon or Siberia, but how it impacts and is relevant to people from Australia and Asia to Europe, South America to Canada and every community in between. The series explores what is happening at the most dramatic tipping points and looks to find answers to understand what can be done to stem the tide of change before we do irreparable damage, and ultimately put our own lives at risk.



The series is hosted by polar explorer and climate journalist Bernice Notenboom, the first woman to climb Mt. Everest and walk to the North and South Poles. She is joined by a number of leading international environmental scientists in each episode, such as Dr. Jason Box, Dr. Matthew England, Professor Peter Cox, and more. In each episode, Notenboom heads off to a far corner of the world to find scientists in the field undertaking vital climate research to try to understand how the climate system is changing and how long we have to make significant changes before we reach a tipping point--a point of no return when our climate system will be changed irreversibly.



The first episode at 9 pm EDT/8 pm CDT this Saturday will be "Amazon Rainforest Risks". "Tipping Points" host Bernice Notenboom will join Peter Cox, Professor of Climate System Dynamics at the University of Exeter, on an expedition across the vast Amazon Rainforest to explore the mega droughts and tree deaths occurring that threaten the forest's survival this century. The Amazon stores CO2 in its soils and biomass equivalent to about fifteen years of human-caused emissions, so a massive die-back of the forest could greatly accelerate global warming. Photosynthesis in the world's largest rainforest keeps the Earth cooler by taking about 2 billion tons of carbon dioxide out of the air each year. However, exceptional droughts in both 2005 and 2010 reversed this process. The Amazon emitted 3 billion tons of CO2 to the atmosphere in 2005, causing a net 5 billion ton increase in CO2 to the atmosphere--roughly equivalent to 19% of the total CO2 emissions to the atmosphere from burning fossil fuels that year. A 2013 NASA-led study found that an area of the Amazon rainforest twice the size of California continues to suffer from the effects of the 2005 mega drought. A 2008 paper by Professor Cox warned that their climate model predicted a rapidly increasing risk of 2005-like droughts from 1-in-20 years in the present climate to 1-in-2 years by 2025, if we continue emitting CO2 at our current "business-as-usual" pace. A 2013 study by Fu et al. found that the dry season length has grown by about seven days per decade in the southern part of the rainforest. If this trend continues in coming decades at half of that rate, the fire season that contributed to the 2005 drought would become the new norm by the late 21st century. The leader of the study, Rong Fu, explained: "The dry season over the southern Amazon is already a marginal for maintaining rainforest. At some point, if it becomes too long, the rainforest will reach a tipping point."



Typhoon Francisco headed towards Japan
Category 4 Typhoon Francisco continues to intensify over the warm waters of the Western Pacific about 200 miles west of Guam. Even though the eye of Francisco passed more than 150 miles west of Guam Friday morning, the huge storm brought sustained winds of 37 mph, gusting to 46 mph, to the island, along with 6.75" of rain. Satellite loops show that Francisco is well-organized with an impressive area of heavy thunderstorms and a prominent eye. With warm waters that extend to great depth and low wind shear, continued strengthening is likely, and Francisco is forecast to become a super typhoon with 150 mph winds by Saturday as it heads northwest towards Japan. The European model now shows that Francisco will miss Japan, but the GFS model predicts that Francisco will hit Japan on Thursday next week. There is very high uncertainty in the storm's track that far into the future, since the timing of Francisco's turn the northeast is difficult to predict.

The Atlantic is quiet
None of the reliable computer models for forecasting tropical cyclone genesis is predicting development over the next five days.

Jeff Masters

Climate Change

Category 2 Francisco Brushing Guam, and is a Long-Range Threat to Japan

By: JeffMasters, 2:48 PM GMT on October 17, 2013

Category 2 Typhoon Francisco is steadily intensifying over the warm waters of the Western Pacific about 160 miles southwest of Guam. The typhoon is expected to make its closest approach to Guam on Friday morning (local time), bringing sustained winds of 35 - 45 mph and heavy rain, as the storm heads north-northeast at 9 mph. Long range radar out of Guam and satellite loops show that Francisco is well-organized with an impressive area of heavy thunderstorms and a prominent eye. With warm waters that extend to great depth and low wind shear, continued strengthening is likely, and Francisco is forecast to become a major Category 4 typhoon by Saturday as it turns northwest towards Japan. Both the GFS and European models predict that Francisco will hit Japan on Wednesday or Thursday next week, though there is very high uncertainty in the storm's track that far into the future. Francisco's formation gives the Western Pacific 27 named storms so far in 2013, which is the average number of named storms for an entire year. The last time there were more than 27 tropical storms or typhoons in the Western Pacific was in 2004, when there were 32.


Figure 1. View of Typhoon Francisco from the long range radar out of Guam.


Figure 2. MODIS satellite image of Typhoon Francisco, taken at approximately 03 UTC on October 16, 2013. At the time, Francisco had top winds of about 85 mph. Image credit: NASA.

18 dead, 40+ missing in Japan after Typhoon Wipha
Typhoon Wipha roared past Japan on Tuesday as a Category 1 typhoon, bringing destructive winds and high rains that triggered flooding being blamed for at least 18 deaths. Most of the deaths occurred on Izu Oshima island, about 75 miles south of Tokyo. An astonishing 33.44" (824 mm) fell in just 23 hours on the island, triggering flash floods and mudslides that killed 17 people and left at least 40 missing. During one incredibly wet 6-hour period, 549.5 mm fell, setting a new 6-hour precipitation record for Japan. The previous record was 502.0 mm at Tarama, Okinawa, on April 28, 1988. According to weather records researcher Maximiliano Herrera, the 24-hour total at Oshima Island was the third highest 24-hour rainfall for Japan on record; the record is 851.5 mm at Yanase (Kochi Prefecture) on 19 July 2011, and 2nd place is the 844 mm that fell at Takeshi (Nara) on 1 August 1982. Wipha is the fourth named storm to hit Japan so far in 2013, and the deadliest typhoon to hit Japan since Typhoon Tokage of October 2004. An average of 2.8 tropical storms or typhoons per year hit Japan during the period 1951 - 2003. Japan's record busiest year was 2004, when ten named storms hit, six of them at Category 1 or higher strength. Jeffrey Hayes has put together a nice summary of Japan's typhoon history.

The Atlantic is quiet
None of the reliable computer models for forecasting tropical cyclone genesis is predicting development over the next five days. NHC is giving 10% odds that an area of disturbed weather (Invest 99L) about 200 miles north-northeast of Bermuda headed northeast out to sea, will develop. During the last few days of October and the first week of November, the Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, is predicted to transition into a phase that will bring an increase in upward-moving air over the Atlantic, boosting the odds of tropical storm formation. The most likely area for formation will be in the Western Caribbean or Gulf of Mexico.

Jeff Masters

Hurricane

Typhoon Wipha's 32 Inches of Rain Kills 17 in Japan

By: JeffMasters, 2:59 PM GMT on October 16, 2013

Typhoon Wipha roared past Japan on Tuesday as a Category 1 typhoon, bringing destructive winds and high rains that triggered flooding being blamed for at least 17 deaths. Most of the deaths occurred on Izu Oshima island, about 75 miles south of Tokyo. An astonishing 32.44" (824 mm) fell in just 23 hours on the island, triggering flash floods and mudslides that killed 16 people and left 50 missing. During one incredibly wet 6-hour period, 549.5 mm fell, setting a new 6-hour precipitation record for Japan. The previous record was 502.0 mm at Tarama, Okinawa, on April 28, 1988. According to weather records researcher Maximiliano Herrera, the 24-hour total at Oshima Island was the third highest 24-hour rainfall for Japan on record; the record is 851.5 mm at Yanase (Kochi Prefecture) on 19 July 2011, and 2nd place is the 844 mm that fell at Takeshi (Nara) on 1 August 1982. Tokyo received 9.69" (246 mm) of rain in 19 hours from Wipha, with winds that reached 50 mph, gusting to 72 mph. At the time Wipha was deluging Tokyo, the typhoon was merging with a cold front and undergoing the transition to an extratropical storm--the same process Hurricane Sandy underwent as it approached landfall in New Jersey in October 2012. The counter-clockwise flow of air around the center of Wipha lifted up copious amounts of tropical moisture over a cold front over Japan, resulting the near-record rainfall amounts observed.


Figure 1. A house and an electric pole smashed by large rocks from a collapsed slope caused by heavy rain in Kamakura, suburban Tokyo on October 16, 2013. JIJI PRESS/AFP/Getty Images


Figure 2. Extreme rainfall of 33.44" in 24 hours from Typhoon Wipha hit Oshima Island, Japan, about 75 miles south of Tokyo, on October 16, 2013. At least 16 people died in this landslide, and 50 are missing. JIJI PRESS/AFP/Getty Images

Tropical Storm Francisco is headed towards Japan
It's been an active October for typhoons in the Western Pacific, and there is at least one more typhoon on the way. Tropical Storm Francisco has formed in the waters east of the Philippines, and is forecast to become a major Category 4 typhoon by Sunday as it heads north-northwest towards Japan. Both the GFS and European models predict that Francisco will come very close to Japan on Wednesday, October 23. Satellite images show that Francisco has already developed an impressive area of heavy thunderstorms with very cold cloud tops, and is strengthening. Francisco's formation gives the Western Pacific 27 named storms so far in 2013. That is the average number of named storms the Western Pacific sees during an entire year. The last time there were more than 27 tropical storms or typhoons in the West Pacific was in 2004, when there were 32.

Wipha's place in history
Wipha is the fourth named storm to hit Japan so far in 2013, and the deadliest typhoon to hit Japan since Typhoon Tokage of October 2004. The other named storms to hit Japan in 2013 were Tropical Storm Man-Yi on September 16, Tropical Storm Toraji on September 4, and Typhoon Danas, which hit Okinawa on October 7. An average of 2.8 tropical storms or typhoons per year hit Japan during the period 1951 - 2003. Japan's record busiest year was 2004, when ten named storms hit, six of them at Category 1 or higher strength. Jeffrey Hayes has put together a nice summary of Japan's typhoon history. The CIMSS Satellite Blog has an interesting analysis of Wipha.

The Atlantic is quiet
None of the reliable computer models for forecasting tropical cyclone genesis is predicting development over the next five days. NHC is giving 10% odds that a blob of disturbed weather near Bermuda headed north to northeast out to sea will develop.

Jeff Masters

Hurricane

Dangerous Typhoon Wipha Drenching Japan

By: JeffMasters, 3:45 PM GMT on October 15, 2013

Large and powerful Category 1 Typhoon Wipha is bearing down on Japan as the storm races northeast at 28 mph. Wipha is likely to be the strongest typhoon to hit Japan since Typhoon Tokage of October 2004, according to the Japan Meteorological Agency. Wipha is merging with a cold front and undergoing the transition to an extratropical storm--the same process Hurricane Sandy underwent as it approached landfall in October 2012. While Typhoon Wipha is not as powerful as Sandy, it does have a huge area of winds in excess of 50 knots (57.5 mph), which extend out 130 miles to the left of the center. Since the center of Wipha is expected to graze the southern coast of Japan today, and the storm will only weaken slightly, a 100-mile-wide swath of Japan will see damaging winds of 50 knots, according to the Japan Meteorological Agency. About a 30 mile-wide swath of Japan will experience winds of 75 mph (hurricane force.) Tokyo will be right at the edge of the hurricane-force wind swath. With many trees still in leaf, these winds will cause widespread tree damage and downed power lines. The counter-clockwise flow of moist, tropical air around the center of Wipha is meeting up with the cold front currently over Japan. This is generating torrential rains over large portions of the country, as the moist air is forced upwards over the cold front, making the air expand and cool, condensing its copious moisture. Radar precipitation estimates show that rainfall rates of 1 - 2" per hour were occurring near Tokyo today. Heavy rains of 4 - 8" capable of causing damaging flooding will be widespread over Japan, including over the Fukushima nuclear site, where rainfall from Typhoon Man-Yi on September 16 complicated clean-up efforts of the reactors damaged by the March 2011 earthquake and tsunami.

Japan may not be all done with typhoons this month, as both the GFS and European models are predicting that an area of disturbed weather (Invest 93W) east of the Philippines will develop into a tropical storm late this week, which will then head northwest and threaten Japan by next Wednesday, October 23.


Figure 1. MODIS satellite image of Typhoon Wipha approaching Japan, taken at approximately 04:25 UTC on October 15, 2013. At the time, Wipha was a Category 1 storm with winds of 90 mph. Image credit: NASA.

Typhoon Nari hits Vietnam
Torrential rains are falling in Southeast Asia due to Typhoon Nari, which made landfall near Da Nang around 03 UTC on Wednesday as a Category 1 typhoon with 80 mph winds. The eye passed 10 miles south of Da Nang, putting the city in the stronger northern semicircle of the storm. Da Nang recorded top sustained winds of 55 mph, gusting to 81 mph, and picked up 4.06" of rain. Damage is heavy in Da Nang, and at least five deaths are being blamed on the storm. Nari battered the Philippines on Friday, killing thirteen people and leaving 2.1 million people without power on the main Philippine island of Luzon.

The Atlantic is quiet
The tropical wave (Invest 98L) a few hundred miles east of the Lesser Antilles Islands that we've been tracking this week has been torn apart by high winds, and is no longer a threat to develop. There are no threat areas in the Atlantic to discuss today, and none of the reliable computer models for forecasting tropical cyclone genesis is predicting development over the next five days.


Figure 2. MODIS satellite image of Tropical Storm Octave (top) and Tropical Storm Priscilla (bottom) taken at approximately 18:30 UTC (2:30 pm EDT) on October 14, 2013. At the time, Octave had top winds of 50 mph, and Priscilla had top winds of 45 mph. Image credit: NASA.

Tropical Depression Octave in the Eastern Pacific bringing needed rain to Texas
In the Eastern Pacific, we have two tropical cyclones: Tropical Storm Priscilla, a minimal-strength tropical storm that is weakening and heading northwest out to sea, and Tropical Depression Octave, which hit Mexico's Baja Peninsula early Wednesday morning. Octave and Priscilla are embedded in a large plume of tropical moisture that is riding up to the northeast over Mexico and Texas. Flood watches and warnings are posted over much of the southern half of Texas, where widespread rains of 2 - 6" have fallen over the past two days. While the heavy rains have caused some minor to moderate flooding, the precipitation is mostly welcome, as it will make a substantial dent in the multi-year drought that has gripped much of Texas.


Video 1. Waterspout observed offshore of Cabo San Lucas, Mexico on October 14, 2013, as rains bands from Tropical Storm Octave moved over the Baja Peninsula.

Jeff Masters

Hurricane

Heavy Damage in India From Phailin, but a Low Death Toll

By: JeffMasters, 2:49 PM GMT on October 14, 2013

Tropical Cyclone Phailin has left behind a shattered coast in northeast India's Odisha region, but a remarkably low death toll, after making landfall on Saturday near the town of Gopalpur. According to media reports, the death toll from the cyclone is the 22 - 36 range, which is extremely low, considering this is a region where 10,000 died in a similar-strength cyclone in 1999. The India Meteorological Department (IMD) provided excellent early warning information for Phailin, predicting on October 9 that the cyclone would strike on October 12 with at least Category 2-strength winds. Civil defense in India took the warnings seriously, and operated the largest evacuation effort in the nation's history--nearly 1 million people--one that undoubtedly saved hundreds of lives. There were far more shelters available to put the evacuees in, compared to in 1999, thanks to a major effort to build more shelters after the terrible 1999 Odisha cyclone. The high death toll in the 1999 cyclone was blamed, in part, due to lack of shelters.


Figure 1. Evacuated Indian villagers get down from a truck at a relief camp as it rains near Berhampur, India, Saturday, Oct. 12, 2013. (AP Photo/Bikas Das)


Figure 2. Villagers take refuge in a cyclone shelter at Gokhorkuda village in, Ganjam district about 200 kilometers (125 miles) from the eastern Indian city Bhubaneswar, India, Saturday, Oct. 12, 2013. (AP Photo/Biswaranjan Rout)

According to media reports, Phailin brought a storm surge of up to 3.5 meters (11 feet) to portions of the coast. I estimate the cyclone's winds were 125 - 140 mph at landfall--Category 3 to 4. The pressure bottomed out at 938 mb in Gopalpur as the eye passed over. At its peak strength 12 hours before landfall, the Joint Typhoon Warning Center (JTWC) rated Phailin as a Category 5 storm with 160 mph winds. JTWC has rated only three other Bay of Bengal cyclones that strong: the 1999 Odisha Cyclone (10,000 killed in India), Cyclone Sidr of 2007 (4,200 killed in Bangladesh), and the 1991 02B cyclone that hit Bangladesh (138,000 killed.) All had top winds of 160 mph. There has only been one Category 5 cyclone on record in the Arabian Sea, Cyclone Gonu of 2007 (165 mph winds.) Accurate satellite records of North Indian Ocean tropical cyclones go back no earlier than 1980.


Figure 3. Indian fishermen look at boats destroyed by Cyclone Phailin at the Gopalpur Port on October 14, 2013. (MANAN VATSYAYANA/AFP/Getty Images)

Typhoon Wipha a heavy rainfall threat for Japan
Huge and powerful Category 2 Typhoon Wipha is now weakening as it heads north towards Japan. The storm peaked as a Category 4 storm with 135 mph winds on Sunday, but has weakened to 110 mph winds, despite warm ocean temperatures of 28 - 29°C and moderate wind shear of 10 - 15 knots, because of an eyewall replacement cycle and ingestion of dry air. On Tuesday, Wipha will encounter cooler waters and higher wind shear, which should substantially weaken the storm as it recurves to the northeast and passes just offshore from Tokyo. The coast of Japan should experience winds below hurricane force, if the core of Wipha passes offshore as expected, but heavy rains of 4 - 8" capable of causing damaging flooding will likely affect portions of the coast, including Tokyo. Heavy rains from Wipha may be a concern for the Fukushima nuclear site, where rainfall from Typhoon Man-Yi on September 16 complicated clean-up efforts of the reactors damaged by the March 2011 earthquake and tsunami.


Figure 4. MODIS satellite image of Typhoon Wipha, taken at approximately 02:30 UTC on October 14, 2013. At the time, Wipha was a Category 3 storm with winds of 125 mph. Image credit: NASA.

Typhoon Nari nearing landfall in Vietnam
Torrential rains are falling in Vietnam due to Category 1 Typhoon Nari, which is nearing landfall in the central part of the country. More than 180,000 people have been evacuated in advance of the storm. Nari battered the Philippines on Friday, killing thirteen people and leaving 2.1 million people without power on the main Philippine island of Luzon.

98L in the Eastern Atlantic disorganized
A tropical wave (Invest 98L) about 700 miles east of the Lesser Antilles Islands is headed west-northwest at 10 mph. Satellite loops show that 98L has lost most of its organization and heavy thunderstorms. The disturbance is under a high 20 - 30 knots of wind shear, and the shear is expected to remain high for the next two days. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 0%, and 5-day odds of 10%. 98L's projected west-northwest track is expected take it close to the Northern Lesser Antilles Islands by Thursday, according to the 00Z Monday run of the European model.

Moisture associated with Tropical Storm Octave in the Eastern Pacific bringing needed rain to Texas
In the Eastern Pacific, we have two tropical cyclones: newly-developed Tropical Storm Priscilla, and Tropical Storm Octave. Octave is the only one that is a threat to land, and the 60-mph tropical storm is headed NNW towards Mexico's Baja Peninsula, where 3 - 6" of rain is expected over the next few days. Octave is expected to dissipate before making it to Baja, due to increasing dry air and wind shear. Octave and Priscilla are embedded in a large plume of tropical moisture that is riding up to the northeast over Mexico and Texas. Flood watches and warnings are posted over many areas of Texas, where widespread rains of 2 - 6" have fallen over the past day. While the heavy rains have caused some moderate flooding, the precipitation is mostly welcome, as it will make a substantial dent in the multi-year drought that has gripped much of Texas. Wunderblogger Lee Grenci makes the point in his latest post that much of the moisture generating the heavy rains in Texas is actually coming from the Gulf of Mexico, due to the clockwise flow of low-level air around a high pressure system over the Upper Midwest.

Jeff Masters

Hurricane

Powerful Cyclone Phailin not a Mega-Disaster for India

By: JeffMasters, 4:56 PM GMT on October 13, 2013

Tropical Cyclone Phailin has weakened to a tropical storm over northern India after making landfall on the northeast coast of India near the town of Gopalpur (population 7,000) at 15:45 UTC (11:45 am EDT) on Saturday, October 12, 2013. According to media reports from the BBC, the cyclone brought a storm surge in excess of 3 meters (10 feet) to portions of the coast, and at least fourteen people had been killed by the storm. Phailin was weakening substantially at landfall, due to interaction with land, and was rated a Category 4 storm with 140 mph winds by the Joint Typhoon Warning Center (JTWC), four hours before landfall. The pressure bottomed out at 938 mb in Gopalpur as the eye passed over, and the city reported sustained winds of 56 mph, gusting to 85 mph, in the eyewall. A 938 mb pressure is what one expects to find in a Category 4 storm with 140 mph winds, using the "Dvorak technique" of satellite wind and pressure estimation, but I expect Phailin's winds were at Category 3 strength, 125 - 130 mph, at landfall, due to the eyewall replacement cycle that was going on at the time. The India Meteorology Department (IMD) still rated Phailin as a Category 2 storm with winds over 100 mph six hours after making landfall, when it was about 60 miles inland. Satellite images show that Phailin's most intense thunderstorms and heaviest rains are no longer near the coast, but have pushed inland near the India/Nepal border. Rainfall amounts as high as 9.49" (241 mm) were reported in the Odisha region where Phailin made landfall.


Figure 1. MODIS satellite image of Tropical Cyclone Phailin, taken at approximately 07:30 UTC on October 13, 2013. At the time, Phailin was a tropical storm with winds 70 mph. Image credit: NASA.

A victory for India's cyclone evacuation and preparation efforts
While we have yet to hear from the worst affected area, the town of Gopalpur in Odisha where the eye of Phailin came ashore, it is clear that India has avoided a humanitarian mega-disaster like occurred in October 1999, when the great 1999 Odisha Cyclone killed nearly 10,000 people in the same region of the county. The India Meteorology Department (IMD) provided excellent early warning information for Phailin, predicting on October 9 that the cyclone would strike on October 12 with at least Category 2-strength winds. Civil defense in India took the warnings seriously, and operated the largest evacuation effort in the nation's history--nearly 1 million people--one that undoubtedly saved hundreds of lives. There were far more shelters available to put the evacuees in, compared to in 1999, thanks to a major effort to build more shelters after the cyclone. The high death toll in the 1999 cyclone was blamed, in part, due to lack of shelters.

How strong was Phailin?
According to satellite strength estimates made by the U.S. Joint Typhoon Warning Center (JTWC), Phailin was just as strong as the great 1999 Odisha Cyclone, 12 hours before landfall. Both storms were rated as Category 5 storms with winds of 160 mph. The India Meteorological Department (IMD) strength estimates for Phailin were considerably lower than that of JTWC, but since both centers use satellite estimates rather than direct measurements of the winds and pressure, we don't know which center was correct. It is true that satellite estimates using the same techniques give different central pressures for the Atlantic and Pacific Oceans--i.e., a storm with the same appearance on satellite imagery will have a higher pressure in the Atlantic than in the Pacific (see this chart of the differences.) However, the satellite estimates give the same winds for each ocean, since the lower pressures in the Pacific are due to the fact that background pressures in the Pacific are lower, and it takes a much lower central pressure to generate the same winds as in an Atlantic storm. It may be the satellite-wind relationship is different in the Indian Ocean, though. IMD has looked at some buoy data to try and calibrate their satellite strength estimates, but high-end tropical cyclones are uncommon enough in the Indian Ocean that I doubt we really know whether or not Indian Ocean cyclones have the same winds as a hurricane in the Atlantic with the same satellite signature. Another thing to consider is that the IMD uses 3-minute average winds for their advisories, and JTWC uses 1-minute, so the winds in the IMD advisories will be lower by at least 2%, due to the longer averaging period. (I said incorrectly that IMD uses 10-minute averaging times in my Saturday blog post.) We need a hurricane hunter aircraft in the Indian Ocean to fly into tropical cyclones and take measurements of the actual winds to resolve the issue.


Figure 2. Triple trouble: Tropical Cyclone Phailin, Typhoon Nari, and Typhoon Wipha parade across the Earth in this MODIS satellite image montage taken on October 13, 2013. Image credit: NASA.

Typhoon Nari heads for Vietnam
Category 2 Typhoon Nari is headed for landfall in Vietnam, after battering the Philippines on Friday. Nari killed thirteen people and left 2.1 million people without power on the main Philippine island of Luzon, after hitting on Friday night near midnight local time as a Category 3 typhoon with 115 mph winds. The core of the storm passed about 80 miles north of the capital of Manila, sparing the capital major flooding, but the storm dumped torrential rains in excess of ten inches to the northeast of Manilla. Nari is under moderate wind shear of 10 - 20 knots, which should keep intensification relatively slow, and increasing interaction with land will also act to slow intensification. Nari is expected to be at Category 1 strength when it makes landfall in Vietnam near 20 - 23 UTC on Monday.

Typhoon Wipha a threat to Japan
Huge and powerful Category 4 Typhoon Wipha continues intensifying as it heads northwest towards Japan. The storm is expected to peak at 145 mph winds on Monday near 12 UTC. By Tuesday, Wipha will recurve to the northeast and begin weakening, passing just offshore from Tokyo, Japan, sometime between 00 - 06 UTC on Wednesday. Wipha will be rapidly weakening as it makes its closest approach to Tokyo, due to high wind shear and cooler waters, and the coast of Japan should experience winds below hurricane force if the core of Wipha passes offshore as expected. High winds and heavy rains from Wipha may be a concern for the Fukushima nuclear site, where rainfall from Typhoon Man-Yi on September 16 complicated clean-up efforts of the reactors damaged by the March 2011 earthquake and tsunami.

98L in the Eastern Atlantic disorganized
A tropical wave (Invest 98L) 900 miles east of the Lesser Antilles Islands is headed west-northwest at 10 mph. Satellite loops show that 98L has lost most of its organization and heavy thunderstorms. The disturbance is under a high 20 - 30 knots of wind shear, and the shear is expected to remain high for the next two days. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 10%, and 5-day odds of 10%. 98L's projected west-northwest track is expected take it close to the Northern Lesser Antilles Islands by Thursday, according to the 00Z Sunday run of the European model.

Moisture associated with Tropical Storm Octave in the Eastern Pacific bringing rain to Texas
In the Eastern Pacific, Tropical Storm Octave is headed NNW towards Mexico's Baja Peninsula, but is expected to dissipate before making it there. Octave is embedded in a large plume of tropical moisture that is riding up to the northeast over Mexico and Texas. Flood Watches are posted over large regions of Texas, where widespread rains of 2 - 4", with some 6 - 8" amounts, are expected.

Jeff Masters

Hurricane

Category 4 Cyclone Phailin Hits India; 13 Dead in Philippines From Typhoon Nari

By: JeffMasters, 5:44 PM GMT on October 12, 2013

Very dangerous Tropical Cyclone Phailin has made landfall on the northeast coast of India near the town of Gopalpur (population 7,000) at 16 UTC (noon EDT) Saturday, October 12, 2013. Phailin was weakening substantially at landfall, due to interaction with land, and was rated a Category 4 storm with 140 mph winds by the Joint Typhoon Warning Center (JTWC), four hours before landfall. The pressure bottomed out at 938 mb in Gopalpur as the eye passed over, and the city reported sustained winds of 56 mph, gusting to 85 mph, in the eyewall. A 938 mb pressure is what one expects to find in a Category 4 storm with 140 mph winds, using the "Dvorak technique" of satellite wind and pressure estimation. Satellite images show that Phailin's intense thunderstorms have warmed and shrunk in areal coverage, and radar out of Visakhapanam, India also shows a weakening of the storm's echoes as it pushes inland. Phailin is bringing torrential rains of over an inch per hour, as estimated by microwave satellite instruments.


Figure 1. Radar image of Phailin at landfall. Image credit: IMD.


Figure 2. MODIS satellite image of Tropical Cyclone Phailin, taken at approximately 07:30 UTC on October 12, 2013. At the time, Phailin was a top-end Category 4 storm with winds of 150 mph. Image credit: NASA.

Damage from Phailin
Phailin is the strongest tropical cyclone to affect India in fourteen years, since the great 1999 Odisha Cyclone. That storm hit with maximum sustained winds of 155 mph, and brought a storm surge of 5.9 meters (19 feet) to the coast. Phailin should be able to drive a similar-sized storm surge to the coast, since it is larger in areal extent than the 1999 cyclone (although somewhat weaker, with winds perhaps 20 - 30 mph lower.) Phailin's storm surge and Category 3 to 4 winds will cause near-catastrophic damage to a 50-mile wide swath of the coast where the eyewall comes ashore, and to the right. Hurricane Katrina was weaker at landfall than Phailin, but Katrina had hurricane-force winds that covered a much larger area, making Katrina's storm surge much more devastating than Phailin's will be. I think the main danger from Phailin will be from its winds. I am particularly concerned about Phailin's wind damage potential in the city of Brahmapur (population 350,000), the 58th largest city in India. Brahmapur lies about ten miles inland, and will likely experience sustained hurricane-force winds for several hours. Phailin's flooding potential is another huge concern, as rainfall amounts of 6 - 12 inches will fall along a swath over 100 miles inland, triggering life-threatening flash flooding.

How strong was Phailin?
Questions have been raised about the India Meteorological Department (IMD) assessments of Phailin's strength, which were considerably lower than that of the U.S. Joint Typhoon Warning Center (JTWC). Both centers use satellite estimates rather than direct measurements of the winds, so we don't know which center is correct. It is true that satellite estimates using the same techniques give different results for the Atlantic and Pacific Oceans--i.e., a storm with the same appearance on satellite imagery will be weaker in the Atlantic than in the Pacific (see this chart of the differences.) It may be that this is the case in the Indian Ocean as well. IMD has looked at some buoy data to try and calibrate their satellite strength estimates, but high-end tropical cyclones are uncommon enough in the Indian Ocean that I doubt we really know whether or not Indian Ocean cyclones have the same winds as a hurricane in the Atlantic with the same satellite signature. Another thing to consider is that the IMD uses 3-minute average winds for their advisories, and JTWC uses 1-minute, so the winds in the IMD advisories will be lower by at least 2%, due to the longer averaging period. This issue could be cleared up if India had its own hurricane hunter aircraft; there have been some high-level discussions about India getting a C-130 aircraft like the U.S. Air Force uses to fly into tropical cyclones and take measurements of the actual winds.


Figure 3. MODIS satellite image of Typhoon Nari, taken at approximately 02:30 UTC on October 12, 2013. At the time, Nari was a Category 1 storm with winds of 90 mph. Image credit: NASA.

Typhoon Nari hits the Philippines
Thirteen people were killed and 2.1 million people lost power on the main Philippine island of Luzon afterTyphoon Nari hit on Friday night near midnight local time. Nari was a Category 3 typhoon with 115 mph winds a few hours before landfall. The core of the storm passed about 80 miles north of the capital of Manila, sparing the capital major flooding, but the storm dumped torrential rains in excess of ten inches to the northeast of Manilla. Passage over Luzon weakened Nari to a Category 1 storm, but it is already beginning to re-organize over the South China Sea between the Philippines and Vietnam. Nari is under moderate wind shear of 15 - 20 knots, which should keep intensification relatively slow, and increasing interaction with land will act to slow intensification on Sunday and Monday. Nari could be near Category 3 strength with 115 mph winds by Monday, and landfall in Vietnam is expected around 21 UTC on Monday.

Typhoon Wipha a threat to Japan
Category 1 Typhoon Wipha is intensifying as it heads northwest towards Japan, and the storm is expected to reach major Category 3 strength by Monday. By Tuesday, Wipha will recurve to the northeast and begin weakening, passing very close to Tokyo, Japan, sometime between 00 - 12 UTC on Wednesday. High winds and heavy rains from Wipha may be a concern for the Fukushima nuclear site, where workers continue to struggle with high radiation levels in the wake of the 2011 tsunami that damaged the reactors.

98L in the Eastern Atlantic weakening
A tropical wave (Invest 98L) located midway between Africa and the Lesser Antilles Islands is headed west to west-northwest at 10 - 15 mph. Satellite loops show that 98L has lost most of its organization and heavy thunderstorms since this morning. The disturbance is under a high 20 - 30 knots of wind shear, and the shear is expected to remain high for the next three days. The UKMET model shows some weak development of 98L by early next week, but the European and GFS models do not. In their 2 pm EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 30%, and 5-day odds of 30%. 98L's projected west-northwest track is expected take it close to the Northern Lesser Antilles Islands by Wednesday, according to the 00Z Saturday run of the European model.

Thanks go to wunderground member thunderfrance for posting the link to the weather station at Gopalpur, India.

NDTV in India has a Live Blog on Phailin with the latest developments.

Jeff Masters

Hurricane

Category 5 Phailin Nears India; Category 3 Nari Hits the Philippines

By: JeffMasters, 9:35 PM GMT on October 11, 2013

Extremely dangerous Tropical Cyclone Phailin has maintained Category 5 strength for six hours, and is expected to remain a Category 5 storm until it is just a few hours from landfall on the northeast coast of India on the Bay of Bengal, according to the 5 pm EDT Friday advisory from the Joint Typhoon Warning Center. Phailin put on a phenomenal burst of rapid intensification on Thursday, going from a tropical storm with 65 mph winds to a top-end Category 4 storm with 155 mph winds in just 24 hours, and is now at peak strength of 160 mph, tying it with Super Typhoon Usagi as Earth's strongest tropical cyclone of 2013. Satellite images show that Phailin maintained very intense thunderstorms with cold cloud tops in its eyewall, with the 5 pm EDT Friday satellite estimate of Phailin's central pressure at 911 mb. This makes Phailin equal in strength to the great 1999 Odisha Cyclone, which killed 9,658 people in India's Odisha province. Radar out of Visakhapanam, India shows that heavy rains from the outer bands of Phailin are already affecting the coast, and these bands were bringing rainfall rates of over an inch per hour, as estimated by microwave data from 18 UTC Friday. Phailin is over ocean waters that have warmed since Thursday, and are now 29 - 30°C. These warm waters extend to a lesser depth than before, and ocean heat content has dropped to a moderate 20 - 40 kJ/cm^2. Wind shear remains low, 5 - 10 knots, and Phailin has strong upper-level outflow, thanks to an anticyclone positioned in the upper atmosphere over the cyclone.


Figure 1. Microwave satellite image overlaid on an infrared satellite image of Tropical Cyclone Phailin, taken at approximately 18 UTC on October 11, 2013. At the time, Phailin was a Category 5 storm with winds of 160 mph. Image credit: Navy Research Lab, Monterey.

Forecast for Phailin
Phailin is likely to be the strongest tropical cyclone to affect India in fourteen years, since the great 1999 Odisha Cyclone. The models are in tight agreement that Phailin will make landfall in Northeast India on Saturday between 09 - 15 UTC about 100 miles to the southwest of where the 1999 cyclone hit. The India Meteorological Department (IMD) is predicting that a storm surge of up to 3.5 meters (eleven feet) will hit along a swath a coast to the right of where the center makes landfall. I expect that this is an underestimate, since the 1999 Odisha Cyclone brought a storm surge of 5.9 meters (19 feet) to the coast, and Phailin is larger in areal extent and just as strong. The region of the coast where Phailin is expected to hit is not as low-lying, though, which should keep the death toll due to storm surge much lower compared to the 1999 Odisha Cyclone, where more than 70% of the deaths occurred due to the storm surge. Deforestation of the coastal mangroves in the storm surge zone was associated with increased death toll in that storm, according to Das and Vincent (2009), who concluded, "villages with wider mangroves between them and the coast experienced significantly fewer deaths than ones with narrower or no mangroves.". I expect that Phailin will weaken slightly before hitting the coast, due to interaction with land, and hit as a Category 4 storm with winds of 145 - 155 mph. The 1999 Odisha Cyclone hit land with top winds of 155 mph.


Figure 2. Elevation of the Odisha region of India, with the track of the 1999 Odisha cyclone and forecast track of Phailin overlaid. Phailin is predicted to hit a region of the coast about 100 miles to the southwest of where the 1999 cyclone hit. The coast is not as low-lying to the southwest, which should result in a lower storm surge death toll. The greatest storm surge occurs along the coast to the right of where the center crosses. Image credit: http://www.globalwarmingart.com

Phailin's heavy rains will be capable of causing very destructive flooding; the 00Z Friday rainfall forecast from the HWRF model (Figure 3) calls for a significant swath of 8 - 16" of rain along the path of Phailin inland. Rains from the 1999 Odisha cyclone killed more than 2,000 people in the town of Padmapur, located more than 150 miles from the coast. Deforestation was cited as a contributing cause to these destructive floods that killed 36% of the town's population.


Figure 3. The 00Z Friday rainfall forecast from the HWRF model calls for a significant swath of 8 - 16" of rain along the path of Phailin inland. Image credit: NOAA/NCEP/GFDL.

India's tropical cyclone history
There is good reason to be concerned when a major tropical cyclone forms in the Bay of Bengal. Twenty-six of the thirty-five deadliest tropical cyclones in world history have been Bay of Bengal storms. During the past two centuries, 42% of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27% have occurred in India (Nicholls et al., 1995.) Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history.

References
Kalsi, S.R., N. Jayanthi N, and S.K. Roy Bhowmik, 2004, "A Review of Different Storm Surge Models and Estimated Storm Surge Height in Respect of Orissa Supercyclonic Storm of 29 October, 1999," New Delhi: Indian Meteorological Department.

Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.

Das, S., and J.R. Vincent, 2009, "Mangroves protected villages and reduced death toll during Indian super cyclone", Proc Natl Acad Sci U S A. 2009 May 5; 106(18): 7357–7360. Published online 2009 April 20. doi: 10.1073/pnas.0810440106


Figure 4. Radar image of Typhoon Nari over Luzon Island in the Philippines, taken at 12:53 am local time on October 12, 2013. Image credit: DOST - Project NOAH

Major Typhoon Nari hits the Philippines
Typhoon Nari hit the main Philippine island of Luzon Friday night local time as a Category 3 typhoon with 115 mph winds. The core of the storm passed about 80 miles north of the capital of Manila, and the storm dumped torrential rains in excess of ten inches to the northeast of Manilla, according to satellite estimates. Passage over Luzon weakened Nari, and the typhoon is now emerging into the South China Sea between the Philippines and Vietnam as a Category 2 storm with 105 mph winds. Nari has about two days over water to re-intensify before making a second landfall in Vietnam around 18 UTC on Monday. The 5 pm EDT Friday Joint Typhoon Warning Center advisory predicts that Nari will re-intensify to 110 mph winds, just below Category 3 strength.

Jeff Masters

Hurricane

India Braces for Extremely Dangerous Tropical Cyclone Phailin

By: JeffMasters, 2:01 PM GMT on October 11, 2013

Extremely dangerous Category 5 Tropical Cyclone Phailin is closing in on the northeast coast of India on the Bay of Bengal. Phailin put on a phenomenal burst of rapid intensification on Thursday, going from a tropical storm with 65 mph winds to a top-end Category 4 storm with 155 mph winds in just 24 hours. After reaching peak intensity near 8 pm EDT Thursday, Phailin--whose name means "a sapphire" in Thai--began an eyewall replacement cycle. The eyewall collapsed, and a new, larger-diameter eyewall formed from an outer spiral band. This process typically weakens the top winds of a tropical cyclone by 5 - 15 mph, and satellite estimates of Phailin's central pressure increased from 910 mb to 934 mb during the eyewall replacement cycle, from 04 - 11 UTC Friday. However, satellite images show that Phailin has completed its eyewall replacement cycle and is now re-intensifying, with the cloud tops of the very intense thunderstorms in the eyewall expanding and cooling, as updrafts in the eyewall grow stronger and push the clouds higher into the atmosphere. The latest satellite estimate of Phailin's central pressure had dropped to 920 mb as of 13 UTC (9 am EDT) on Friday, and the Joint Typhoon Warning Center upped Phailin's intensity to a Category 5 storm with 160 mph winds in their 11 am EDT Friday advisory. Radar out of Visakhapanam, India shows that heavy rains from the outer bands of Phailin are already affecting the coast, and these bands were bringing rainfall rates of over an inch per hour, as estimated by microwave data from 10:55 UTC Friday. Phailin is over ocean waters that have warmed since Thursday, and are now 29 - 30°C. These warm waters extend to a lesser depth than before, and ocean heat content has dropped to a moderate 20 - 40 kJ/cm^2. Wind shear remains low, 5 - 10 knots.


Figure 1. MODIS satellite image of Tropical Cyclone Phailin, taken at approximately 04:30 UTC on October 11, 2013. At the time, Phailin was a top-end Category 4 storm with winds of 155 mph. Image credit: NASA.

Forecast for Phailin
Phailin is likely to be the strongest tropical cyclone to affect India in fourteen years, since the great 1999 Odisha Cyclone. That terrible storm hit Northeast India in the Indian state of Odisha (formerly called Orissa) near the city of Bhubaneswar, as a Category 4 storm with 155 mph winds on October 29, 1999. The mighty cyclone, which peaked at Category 5 strength with 160 mph winds and a 912 mb central pressure shortly before landfall, drove a storm surge of at least 19' (5.9 meters) onto the coast (Kalsi et al., 2004.) The storm stalled just inland, dumping torrential rains on portions of India already saturated from the landfall of Category 4 Tropical Cyclone 04B just twelve days before. The catastrophe killed 9,658 people and left $2.5 billion in damage (1999 dollars), India's most expensive and fourth deadliest tropical cyclone in the past 100 years. The models are in tight agreement that Phailin will make landfall in Northeast India on Saturday between 09 - 15 UTC about 100 miles to the southwest of where the 1999 cyclone hit. The India Meteorological Department (IMD) is predicting that a storm surge of up to 3 meters (ten feet) will hit along a swath a coast to the right of where the center makes landfall. This region of the coast is not as low-lying, which should keep the death toll due to storm surge much lower compared to the 1999 Odisha Cyclone, where more than 70% of the deaths occurred due to the storm surge. Deforestation of the coastal mangroves in the storm surge zone was associated with increased death toll in that storm, according to Das and Vincent (2009), who concluded, "villages with wider mangroves between them and the coast experienced significantly fewer deaths than ones with narrower or no mangroves.". Given Phailin's recent recovery from its eyewall replacement cycle and subsequent re-intensification, I expect that Phailin will hit the coast as a Category 4 storm with a strength very similar to that of the 1999 Odisha Cyclone.


Figure 2. Elevation of the Odisha region of India, with the track of the 1999 Odisha cyclone and forecast track of Phailin overlaid. Phailin is predicted to hit a region of the coast about 100 miles to the southwest of where the 1999 cyclone hit. The coast is not as low-lying to the southwest, which should result in a lower storm surge death toll. The greatest storm surge occurs along the coast to the right of where the center crosses. Image credit: http://www.globalwarmingart.com

Phailin's heavy rains will be capable of causing very destructive flooding; the 00Z Friday rainfall forecast from the HWRF model (Figure 3) calls for a significant swath of 8 - 16" of rain along the path of Phailin inland. Rains from the 1999 Odisha cyclone killed more than 2,000 people in the town of Padmapur, located more than 150 miles from the coast. Deforestation was cited as a contributing cause to these destructive floods that killed 36% of the town's population.


Figure 3. The 00Z Friday rainfall forecast from the HWRF model calls for a significant swath of 8 - 16" of rain along the path of Phailin inland. Image credit: NOAA/NCEP/EMC Hurricane Forecast Project supported by Hurricane Forecast Improvement Project (HFIP).

India's tropical cyclone history
There is good reason to be concerned when a major tropical cyclone forms in the Bay of Bengal. Twenty-six of the thirty-five deadliest tropical cyclones in world history have been Bay of Bengal storms. During the past two centuries, 42% of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27% have occurred in India (Nicholls et al., 1995.) Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history.

References
Kalsi, S.R., N. Jayanthi N, and S.K. Roy Bhowmik, 2004, "A Review of Different Storm Surge Models and Estimated Storm Surge Height in Respect of Orissa Supercyclonic Storm of 29 October, 1999," New Delhi: Indian Meteorological Department.

Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.

Das, S., and J.R. Vincent, 2009, "Mangroves protected villages and reduced death toll during Indian super cyclone", Proc Natl Acad Sci U S A. 2009 May 5; 106(18): 7357–7360. Published online 2009 April 20. doi:  10.1073/pnas.0810440106

Little change to 98L in the Eastern Atlantic
A tropical wave (Invest 98L) located about 600 miles west-southwest of the Cape Verde Islands is headed west to west-northwest at about 10 mph. Satellite loops show that 98L has a modest area of heavy thunderstorms with a substantial amount of spin. The disturbance is under a high 20 - 30 knots of wind shear, and the shear is expected to remain high for the next five days. The UKMET model shows some weak development of 98L by early next week, but the European and GFS models do not. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 40%, and 5-day odds of 40%. 98L's projected west-northwest track is expected take it several hundred miles northeast of the Northern Lesser Antilles Islands by the middle of next week, according to the 00Z Friday morning runs of the GFS and European models.


Figure 4. MODIS satellite image of Typhoon Nari, taken at approximately 02:30 UTC on October 11, 2013. At the time, Nari was a Category 3 storm with winds of 115 mph. Image credit: NASA.

Typhoon Nari headed towards the Philippines
In the Western Pacific, we have another very dangerous tropical cyclone--Category 3 Typhoon Nari, which is bearing down on the main Philippine island of Luzon. Nari will make landfall near 16 UTC (noon EDT), bringing the usual hazards of destructive winds, dangerous storm surge, and torrential rains capable of causing life-threatening flash floods and mudslides. The core of the storm will pass about 80 miles north of the capital of Manila, Passage over Luzon is expected to weaken Nari to a Category 1 storm by the time it emerges into the South China Sea between the Philippines and Vietnam. Nari will then have a little over two days to re-intensify before making a second landfall in Vietnam around 18 UTC on Monday.


Video 1. The aftermath of the 1999 cyclone (and rising sea levels). See also this video on the ‪IDRF rehabilitation after the 1999 Odisha Supercyclone‬. Thanks to wunderground member barbamz for posting these links in my blog comments.

Jeff Masters

Hurricane

Category 3 Tropical Cyclone Phailin Rapidly Intensifying, Headed Towards India

By: JeffMasters, 3:22 PM GMT on October 10, 2013

Very dangerous Tropical Cyclone Phailin, in the North Indian Ocean's Bay of Bengal, has put on an impressive burst of rapid intensification, going from a tropical storm with 65 mph winds to a formidable Category 3 storm with 115 mph winds in just twelve hours. Satellite estimates of Phailin's strength at 8 am EDT ranged as high as 135 mph. Satellite images show that Phailin, whose name means "a sapphire" in Thai, continues to intensify. The cloud tops of the very intense thunderstorms in the eyewall are expanding and cooling, showing that their updrafts are growing stronger and pushing the clouds higher into the atmosphere. Water temperatures are warm, 28 - 29°C, and the ocean heat content is very high, 80 - 100 kJ/cm^2--a level often associated with rapid intensification. With wind shear low, Phailin should be able to continue to intensify until an eyewall replacement cycle begins. It is very difficult for a tropical cyclone to maintain an eye diameter less than ten miles across before the inner core grows unstable and the eyewall collapses, with a new, larger-diameter eyewall forming from an outer spiral band. This process typically weakens the top winds of a tropical cyclone by 5 - 15 mph, but spreads hurricane-force winds over a larger area of ocean, resulting a larger storm surge, but less wind damage. With Phailin's eye diameter already down to a tiny 9 miles, an eyewall replacement cycle is likely to occur by Friday morning.


Figure 1. MODIS satellite image of Tropical Cyclone Phailin, taken at approximately 07:30 UTC on October 10, 2013. At the time, Phailin had top winds of 75 mph. Image credit: NASA.

Forecast for Phailin
The models are in tight agreement that Phailin will track northwest into the northeast coast of India, with landfall expected to occur between 06 - 12 UTC on Saturday. The 11 am EDT Thursday forecast from the Joint Typhoon Warning Center predicts that Phailin will peak as a top-end Category 4 storm with 155 mph winds 12 hours before landfall. The India Meteorological Department (IMD) is predicting that Phailin will be a borderline Category 2/Category 3 storm at landfall. The 06Z Thursday run of the HWRF model predicted that Phailin would be a strong Category 3 storm with 130 mph winds at landfall on Saturday.


Figure 2. Storm surge forecast for Tropical Cyclone Phailin, made on October 10, 2013. The peak surge was predicted to be 87 cm (2.9'). This forecast is likely to be a considerable underestimate of the surge, given Phailin's recent rapid intensification. Image credit: IMD.

The Bay of Bengal is notorious for deadly tropical cyclones
There is good reason to be concerned when a major tropical cyclone forms in the Bay of Bengal. Twenty-six of the thirty-five deadliest tropical cyclones in world history have been Bay of Bengal storms. During the past two centuries, 42% of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27% have occurred in India (Nicholls et al., 1995.) Phailin is likely to be the strongest tropical cyclone to affect India in fourteen years, since the great 1999 Odisha Cyclone. That terrible storm hit Northeast India in the Indian state of Odisha (formerly called Orissa) near the city of Bhubaneswar, as a Category 4 storm with 155 mph winds on October 29, 1999. The mighty cyclone, which peaked at Category 5 strength with 160 mph winds and a 912 mb central pressure shortly before landfall, drove a storm surge of 26 feet (8 meters) onto the coast. The storm stalled just inland, dumping torrential rains on portions of India already saturated from the landfall of Category 4 Tropical Cyclone 04B just twelve days before. The catastrophe killed 9,658 people and left $2.5 billion in damage (1999 dollars), India's most expensive and fourth deadliest tropical cyclone in the past 100 years. Although Phailin is expected to hit the same province of India that the great 1999 Odisha Cyclone hit, Phailin's landfall location is predicted to fall about 100 miles farther to the south, in a region where the coast is not as low-lying. This should keep the death toll due to storm surge much lower compared to the 1999 Odisha Cyclone, where more than 70% of the deaths occurred due to the storm surge. The latest storm surge forecast from IMD (Figure 2) predicts a peak surge under 3', but this is much too low, considering Phailin's recent round of rapid intensification. Phailin's heavy rains will be capable of causing great destruction, as did the rains from the 1999 Odisha cyclone. More than 2,000 of the deaths from that storm occurred due to fresh water flooding in the town of Padmapur, located more than 150 miles from the coast. Deforestation was cited as a contributing cause to these destructive floods that killed 36% of the town's population.

Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history.

References
Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.



98L in the Eastern Atlantic more organized
A tropical wave (Invest 98L) located about 400 miles southwest of the Cape Verde Islands is headed west to west-northwest at about 10 mph. Satellite loops show that 98L has a modest area of heavy thunderstorms with a substantial amount of spin. The disturbance is under a moderate 10 - 20 knots of wind shear today, but the shear is expected to rise to the high range, 20 - 30 knots, Friday - Monday, making Thursday the most likely day for development. The UKMET model develops the disturbance into a tropical depression this week, but the European and GFS models do not. In their 8 am EDT Thursday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 50%, and 5-day odds of 50%. 98L's projected west-northwest track is expected take it several hundred miles northeast of the Northern Lesser Antilles Islands by the middle of next week, according to the 00Z Thursday morning runs of the GFS and European models.

Typhoon Nari headed towards the Philippines
In the Western Pacific, Category 1 Typhoon Nari is expected to intensify into a Category 2 storm with 100 mph winds and make landfall on Luzon Island in the Philippines near 12 UTC Friday. Nari will then make a second landfall in Vietnam around 00 UTC on Tuesday.

Jeff Masters

Hurricane

Dangerous Tropical Cyclone Phailin Headed Towards India

By: JeffMasters, 3:09 PM GMT on October 09, 2013

In the North Indian Ocean's Bay of Bengal, Tropical Storm Phailin has formed off the west coast of Thailand, and is moving west-northwest towards India at 8 mph. Satellite images show that Phailin is a medium-sized storm that is increasing in organization and intensity. Water temperatures are warm, 28 - 29°C, and the ocean heat content is very high, 80 - 100 kJ/cm^2--a level often associated with rapid intensification. With wind shear low, Phailin should be able to intensify into at least a Category 1 storm before landfall occurs near 12 UTC on Saturday, as predicted by the Joint Typhoon Warning Center. The India Meteorological Department (IMD) is predicting that Phailin may be able to intensify into a Category 3 storm before landfall. The 12Z Wednesday run of the HWRF model predicted that Phailin would peak as a Category 3 storm with 125 mph winds at landfall on Saturday. The northeast coast of India where Phailin is expected to hit is vulnerable to high storm surges and is densely populated, so Phailin has the potential to be a very dangerous storm.


Figure 1. The great Odisha Cyclone of 1999 at landfall on October 19, 1999 at 05:30 UTC, as seen by the Meteosat satellite. The cyclone hit the Indian state of Odisha (formerly called Orissa) near the city of Bhubaneswar as a Category 4 storm with 155 mph winds, killing 9,658 people and causing $2.5 billion in damage (1999 dollars). Image credit: NOAA.

India's tropical cyclone history
Only two Bay of Bengal tropical cyclones have hit India at hurricane strength since 2000. The most recent was Cyclone Thane,  which hit Southeast India on December 30, 2011, as a Category 1 storm with 75 mph winds. Thane killed 48 people and did $250 million in damage. The most recent major tropical cyclone to hit India was the 1999 Odisha Cyclone, which hit Northeast India in the Indian state of Odisha (formerly called Orissa) near the city of Bhubaneswar as a Category 4 storm with 155 mph winds on October 29, 1999. The mighty storm, which had been at Category 5 strength with 160 mph winds and a 912 mb central pressure shortly before landfall, drove a storm surge of 26 feet (8 meters) onto the coast. The storm stalled just inland, dumping torrential rains on portions of India already saturated from the landfall of Category 4 Tropical Cyclone 04B just twelve days before. The catastrophe killed 9,658 people and left $2.5 billion in damage (1999 dollars), India's most expensive and fourth deadliest tropical cyclone in the past 100 years. Six other Indian tropical cyclones occurring before 1900 were deadlier; see wunderground's list of the 35 Deadliest Tropical Cyclones in World History. During the past two centuries, 42 percent of Earth's tropical cyclone-associated deaths have occurred in Bangladesh, and 27 percent have occurred in India (Nicholls et al., 1995.)

Wunderground's weather historian Christopher C. Burt has a detailed post on India's tropical cyclone history.

References
Nicholls, R.J.N., N. Mimura, J.C. Topping, 1995, "Climate change in south and south-east Asia: some implications for coastal areas," J Glob Environ Eng 1995;1:137–54.

Little change to 98L in the Eastern Atlantic
A tropical wave (Invest 98L) located about 400 miles south-southwest of the Cape Verde Islands is headed west to west-northwest at about 5 - 10 mph. Satellite loops show that 98L has a small area of heavy thunderstorms with a modest amount of spin. The UKMET and GFS models develop the disturbance into a tropical depression late in the week, but the European model does not. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 30%, and 5-day odds of 40%. 98L's projected west-northwest track is expected take it near or just northeast of the Northern Lesser Antilles Islands around Wednesday October 16, according to the 00Z Wednesday morning runs of the GFS and European models.

Tropical Storm Nari headed towards the Philippines
In the Western Pacific, Tropical Storm Nari has formed east of the Philippines, and is expected to intensify into a Category 1 typhoon and make landfall on Luzon Island in the Philippines this weekend, and in Vietnam next week. The GFS and European models predict that a new tropical storm will form east of the Philippines late this week, but recurve to the northeast and not threaten any land areas.

Jeff Masters

Hurricane

98L in Eastern Atlantic no Threat; Bay of Bengal Storm Could be Trouble for India

By: JeffMasters, 2:26 PM GMT on October 08, 2013

A tropical wave (Invest 98L) located about 400 miles south-southwest of the Cape Verde Islands is headed west-northwest at about 5 - 10 mph. Satellite loops show that 98L has a small area of heavy thunderstorms with a modest amount of spin. The UKMET and GFS models develop the disturbance into a tropical depression late in the week, but the European model does not. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 40%, and 5-day odds of 50%. 98L's projected track will take it into the Central Atlantic, where it is unlikely to threaten any land areas. However, a few members of the European model's ensembles of forecasts do show 98L potentially impacting the Northern Lesser Antilles Islands early next week.

Off the U.S. Mid-Atlantic coast, a non-tropical area of low pressure is expected to develop along a stalled cold front just offshore, bringing an extended period of strong on-shore winds that will bring high waves, tides 1 - 2 feet above normal, and beach erosion from Cape Hatteras, North Carolina to Virginia Beach, Virginia. The Surfchex live webcam site has some impressive views of the high surf today from various cameras along the coast.

In the Western Pacific, Typhoon Danas has weakened to a tropical storm with 65 mph winds, and is bringing sustained winds of 40 mph to the south coast of South Korea. The Western Pacific will stay very active this week, with the GFS and European models predicting that two new tropical storms will form east of the Philippines late in the week.

In the North Indian Ocean's Bay of Bengal, a strong tropical disturbance with plenty of spin has developed off the west coast of Thailand, as seen on satellite images. Both the GFS and European models predict that this disturbance will develop into a tropical cyclone by Wednesday. The North Indian Ocean is much easier to predict the formation of Tropical Cyclones for then the Atlantic, so these forecasts are very likely to come true. The storm expected to track to the west-northwest and make landfall in Northeast India on Saturday. Conditions are ripe for this storm to intensify to hurricane strength and drive a dangerous storm surge onto the coast.


Figure 1. MODIS satellite image of tropical disturbance 90W over the eastern Bay of Bengal in the North Indian Ocean, taken at approximately 08:30 UTC on October 8, 2013. The disturbance is expected to develop into a tropical cyclone that will affect Northeast India this weekend. Image credit: NASA.

Jeff Masters

Hurricane

98L in Eastern Atlantic no Threat; Typhoon Danas Takes Aim at Japan

By: JeffMasters, 2:49 PM GMT on October 07, 2013

A tropical wave (Invest 98L) located about 500 miles southwest of the Cape Verdes Islands is headed west-northwest at about 10 mph. Satellite loops show that 98L has a modest area of heavy thunderstorms and spin. The UKMET model develops the disturbance into a tropical depression late in the week, but the GFS and European models do not. In their 8 am EDT Monday Tropical Weather Outlook, NHC gave the disturbance 2-day development odds of 20%, and 5-day odds of 30%. 98L's projected track will take it into the Central Atlantic, where it is unlikely to threaten any land areas. The models are not showing any other threat areas, and the large-scale Atlantic conditions favor below-average chances of tropical storm formation for the next two weeks. These odds may rise by the last week of October and first week of November, when the MJO has a decent chance changing to a phase that will bring upward air motion to the Atlantic.


Figure 1. MODIS satellite image of 98L over the far Eastern Atlantic, taken at approximately 8:30 am EDT on October 7, 2013. The southernmost Cape Verde Islands are visible at upper right. Image credit: NASA.

Typhoon Danas takes aim at Japan
In the Pacific, impressive Typhoon Danas reached Category 4 status with 145 mph winds this morning as it passed just north of Okinawa, becoming the third strongest tropical cyclone on Earth so far in 2013. Only Super Typhoon Usagi (160 mph winds) and Super Typhoon Utor (150 mph winds) have been stronger. Danas has peaked in strength, and satellite loops show that wind shear has begun eating into the intense thunderstorms on the southwest portion of Danas' eyewall. Danas is expected to weaken to Category 2 strength as it recurves to the northeast and passes very close to Nagasaki, Japan around 12 UTC on Tuesday.


Figure 2. MODIS satellite image of Typhoon Danas, taken at approximately 02 UTC on October 7, 2013. At the time, Danas had top winds of about 140 mph. Image credit: NASA.

Tropical Cyclone expected to form in the North Indian Ocean and threaten India
In India, where one of the longest monsoon seasons ever recorded is finally beginning to wane, atmospheric conditions over the North Indian Ocean are growing more conducive for the formation of tropical cyclones. The waters off the west coast of Thailand feature a large area of intense thunderstorms with a pronounced spin, as seen on satellite images. Both the GFS and European models predict that this disturbance will develop into a tropical cyclone by Wednesday, with the storm expected to track to the northwest and make landfall in Northeast India this weekend. This storm has the potential to intensify into a major storm capable of driving a dangerous storm surge onto the coast.

Jeff Masters

Hurricane

Tropical Storm Karen Dissipates

By: JeffMasters, 3:34 PM GMT on October 06, 2013

Tropical Storm Karen degenerated into a post-tropical low pressure system this morning, done in by dry air and high wind shear. Karen's demise brings the seasonal Accumulated Cyclone Energy (ACE) in the Atlantic up to 27, which is about 31% of average for this time of the year. Climatologically, the season should be about 85% over, and I expect we will see just one or two more named storms before the quiet Atlantic hurricane season of 2013 peters out. The next candidate to be a named storm is a low pressure area that emerged off the coast of Africa on Friday, and was located a few hundred miles south-southwest of the Cape Verdes Islands at 11 am Sunday morning. The disturbance is headed west-northwest into the Central Atlantic, and is unlikely to threaten any land areas. In their 8 am EDT Sunday Tropical Weather Outlook, NHC gave the disturbance 5-day development odds of 30%. The UKMET model develops the disturbance into a tropical depression late in the week, but the GFS and European models do not.

One item of interest regarding Karen, noted in the NHC discussion Saturday afternoon at 5 pm EDT:

THE 12Z HWRF RUN SHOWED CONSIDERABLY LESS INTENSIFICATION WITH KAREN COMPARED TO PREVIOUS RUNS AFTER ASSIMILATING DATA FROM THE FROM THE
NOAA P-3 TAIL DOPPLER RADAR. THIS MARKS THE FIRST TIME DOPPLER RADAR DATA HAVE BEEN ASSIMILATED INTO AN OPERATIONAL HURRICANE MODEL IN REAL TIME.

The integration of real-time radar data from the NOAA Hurricane Hunters into the HWRF model may make this model worthy of extra consideration in the future.


Figure 1. The remnants of Tropical Storm Karen were still generating some heavy rains over the Northern Gulf of Mexico at 11 am EDT Sunday morning.

Jeff Masters

Hurricane

Karen Weakens Significantly; 4 Feet of Snow in South Dakota; 18 Tornadoes in Midwest

By: JeffMasters, 3:57 PM GMT on October 05, 2013

Tropical Storm Karen has weakened to a minimal-strength tropical storm with 40 mph winds as it heads towards landfall in Southeast Louisiana. Karen continues to struggle with high wind shear of 25 knots, due to strong upper-level winds out of the west. These winds have driven dry air from the Western Gulf of Mexico into Karen's core, making it difficult for heavy thunderstorms to build on the west and south sides of Karen's center of circulation. Satellite loops show the classic appearance of a sheared storm, with the low level center exposed to view, and the heavy thunderstorms pushed to one side by the high shear. A spiral band on the north side of Karen's center of circulation moved over Southern Louisiana, Mississippi, and Alabama Friday afternoon, bringing a few scattered areas of 1" of rain. Long-range radar out of New Orleans shows a few thunderstorms over land, with the bulk of Karen's rain offshore. Karen brought a storm surge of up to 1.6' above normal along the Louisiana and Mississippi coast Saturday morning, as seen on our wundermap with the storm surge layer turned on.


Figure 1. MODIS satellite image of Tropical Storm Karen, taken at approximately 12:30 pm EDT on October 5, 2013. At the time, Karen had top winds of 40 mph. Image credit: NASA.

Forecast for Karen
The computer models have come into good agreement on the track of Karen, with the storm expected to make landfall in Southeast Louisiana and pass near or to the south of New Orleans early Sunday morning. With wind shear showing no signs of letting up, any strengthening of Karen on Saturday will be slow, and it is more likely that the storm will weaken to a tropical depression with 35 mph winds before landfall. NHC's 11 am EDT Saturday wind probability forecast shows the highest odds of tropical storm-force winds to be at the tip of the Mississippi River at Buras, Louisiana: 47%. New Orleans has a 38% chance, and the rest of the coast from Mississippi to Pensacola, Florida has odds ranging from 20% - 30%. Karen should cause mostly minor damage at landfall, with flooding rains, storm surge, and a few weak tornadoes of concern.


Figure 2. iWitness Anne Zollinger captured this photo of snow accumulation in Wright, WY on October 4, 2013.


Figure 3. Radar reflectivity image of the supercell thunderstorm that spawned the tornado that hit Wayne, Nebraska (marked by the circle with "+" symbol in it.)

A blizzard and a severe weather outbreak in the Midwest
A storm far more intense and dangerous than Tropical Storm Karen is Winter Storm Atlas, which continues to pound the Midwest with a variety of extreme weather today. Blizzard conditions enveloped much of Wyoming and South Dakota on Friday, with an astonishing 48" (4 feet!) of snow falling in Deadwood, South Dakota. Check out this amazing photo of the snow there. The 43.5" of snow that fell in Lead, South Dakota was that city's fourth heaviest snowfall on record. In Rapid City, South Dakota, the airport recorded thundersnow and sustained winds of 44 mph, gusting to 55 mph at 4 pm Friday, before communication were lost. The snow tally so far in the city is 18.3", making it the sixth largest snowfall in recorded history. Casper, Wyoming received 16.2" of snow, their tenth greatest snow storm in recorded history. The storm brought a significant outbreak of severe thunderstorms with very large hail and eighteen preliminary reports of tornadoes, with the most damaging tornado hitting Wayne, Nebraska on Friday afternoon near 5:30 pm CDT, causing millions in damage, and injuring fifteen people. The severe weather threat is much less for Saturday and Sunday, with only a "slight" risk of severe weather being predicted by NOAA's Storm Prediction Center. Wunderground weather historian Christopher C. Burt has done some research to see the last time a blizzard, major severe weather outbreak, tropical storm, and extreme fire danger all threatened the U.S. at the same time, and has not been able to find such an event in past history, as detailed in his latest blog post.

Extremely critical fire threat continues for Southern California
A Santa Ana wind event is in its second day over Southern California in Los Angeles and Ventura Counties, where numerous locations saw wind gusts in excess of 60 mph on Friday. The top wind gust was 75 mph in Santa Paula at 4:45 am Saturday, October 5; the Naval Air Station Point Muga had a gust of 74 mph at 1:54 am Saturday. Strong wind gusts of up to 60 mph, combined with humidity levels of 5 - 10%, will make for extremely critical fire conditions again on Saturday afternoon. Fortunately, no fires were sparked on Friday. Let's keep it that way on Saturday!

I'll have a new post Sunday.

Jeff Masters

Hurricane Winter Weather Tornado

Little Change to Tropical Storm Karen

By: JeffMasters, 8:27 PM GMT on October 04, 2013

Tropical Storm Karen has slowed down a bit to 9 mph but is still heading north-northwest towards Louisiana. An Air Force hurricane hunter plane was in the storm Friday afternoon, and found top surface winds near 50 - 55 mph and a central pressure of 1004 mb. This pressure is 1 mb higher than what the Hurricane Hunters found on Friday morning. NOAA buoy 42001 reported a sustained wind of 44 mph, gusting to 51 mph, at 11:50 am EDT, when the center of Karen passed 40 miles to its southwest. The winds have declined since, as Karen has moved away. A spiral band on the north side of Karen's center of circulation moved over Southern Louisiana, Mississippi, and Alabama early Friday afternoon, bringing up to 1" of rain to isolated areas. Karen continues to struggle with high wind shear of 25 knots, due to strong upper-level winds out of the west. These winds have driven dry air from the Western Gulf of Mexico into Karen's core, making it difficult for heavy thunderstorms to build on the west and south sides of Karen's center of circulation. Satellite loops show the classic appearance of a sheared storm, with the low level center exposed to view, and the heavy thunderstorms pushed to one side by the high shear. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, and ocean temperatures are a very warm 29°C (84°F). Ocean heat content is 20 - 40 kJ per square centimeter, which is fairly typical for this time of year, and does not increase the odds of rapid intensification. Strong southeasterly winds ahead of Karen are pushing tides about 1 - 1.5' above normal along most of the Louisiana and Mississippi coast, as seen on our wundermap with the storm surge layer turned on.


Figure 1. MODIS satellite image of Tropical Storm Karen, taken at approximately 12:30 pm EDT on October 4, 2013. At the time, Karen had top winds of 50 mph. Image credit: NASA.


Figure 2. Wind forecast for 5 am EDT Monday October 7, 2013, from the GFS model run done at 8 am EDT Friday, October 4, 2013. The model is showing that Karen will be at tropical depression strength with winds of at most 35 knots (40 mph) at landfall near Apalachicola. This model run was initialized using data from the NOAA jet, so should be of higher reliability than previous model runs. The image was generated using our wundermap with the model layer turned on.

Forecast for Karen
Wind shear through Sunday afternoon is expected to stay high, around 20 - 30 knots, according to the 2 pm EDT SHIPS model forecast. The GFS , European, and HWRF models predict that Karen will weaken Friday night and Saturday morning as the storm slows down and turns to the north. The GFDL model disagrees, showing slow intensification. On Saturday afternoon, an approaching trough of low pressure will turn Karen sharply to the east-northeast. Most of the models show that Karen will intensify by 10 - 20 mph on Saturday evening and Sunday morning as the storm interacts with this trough, because of diverging winds aloft that will suck up more air from the surface. However, ocean temperatures will have cooled to 28°C by then, limiting the amount of intensification that can occur. Wind shear is forecast to rise to 35 - 40 knots on Sunday evening, which may cause rapid weakening. NHC has again reduced its odds of Karen achieving hurricane strength. The 11 am EDT Friday wind probability forecast from NHC put Karen's best chance of becoming a hurricane as a 14% chance on Sunday at 8 am EDT. This is down from the 21% odds given in the forecast six hours previous to that.

Since Karen is expected to make a sharp course change to the east-northeast near the time it approaches the south coast of Louisiana, the models show a wide range of possible landfall locations. A double landfall is possible, one over the Mississippi River Delta in Southeast Louisiana, and another in the Florida Panhandle. This is the solution of this morning's 12Z (8 am EDT) runs of the European and UKMET models. Karen may stay just offshore of Louisiana and make only one landfall in Alabama or the Florida Panhandle, as predicted by the 12Z runs of the GFS and GFDL models. Most of Karen's heavy thunderstorms will be displaced to the east by high wind shear when the storm makes landfall, and there will likely be relatively low rainfall totals of 1 - 3" to the immediate west of where the center makes landfall. Higher rainfall totals of 3 - 6" can be expected to the east. NHC's 11 am EDT Friday wind probability forecast shows the highest odds of tropical storm-force winds to be at the tip of the Mississippi River at Buras, Louisiana: 59%. New Orleans, Gulfport, Mobile, and Pensacola have odds ranging from 35% - 45%. I expect Karen will cause mostly minor damage at landfall, with flooding rains, storm surge, and a few tornadoes all a concern.

Most significant fire threat for Southern California in the past 5 years
A Santa Ana wind event has begun over Southern California, where wind gusts in excess of 60 mph have already been observed at three mountain locations Friday morning. Strong winds will spread to the valleys by Friday afternoon, and continue through Saturday. From the Los Angeles NWS office:

"Most significant fire weather threat across Southern California in past 5 years as strong Santa Ana wind event unfolds. In addition to the strength of winds being projected...the concerns with this event include the widespread nature and long duration of Santa Ana winds...very long period of single digit humidities...and extremely dry fuels approaching record levels. Red flag warnings are in effect for much of Los Angeles and Ventura counties overnight into Sunday. The onset of the offshore winds are expected to begin across the mountains by late evening...then descend into the lower elevations overnight. The peak of this Santa Ana wind event will likely be late tonight through Saturday morning...with the strongest winds focused across Los Angeles and Ventura counties."


Figure 3. A moderate risk for severe weather is predicted for Friday afternoon over much of Iowa.

A blizzard and a severe weather outbreak in the Midwest
The same low pressure system that is expected to turn Tropical Storm Karen to the northeast this weekend is hammering the Midwest with a variety of extreme weather today. Blizzard conditions enveloped much of Wyoming today, with up to 2' of snow falling at several mountain locations. In Rapid City, South Dakota, where more than a foot of snow is expected, the Police Department has issued a no travel advisory. A significant outbreak of severe thunderstorms with very large hail and a few tornadoes--possibly strong EF2 and EF3s--is expected over much of Iowa early this evening. Wunderground weather historian Christopher C. Burt has done some research to see the last time a blizzard, major severe weather outbreak, tropical storm, and extreme fire danger all threatened the U.S. at the same time, and has not been able to find such an event in past history, as detailed in his latest blog post.

I'll have a new post Saturday by noon.

Jeff Masters

Hurricane

Little Change to Karen; U.S. HIt By a Blizzard, Severe Weather, and Santa Ana Winds

By: JeffMasters, 1:44 PM GMT on October 04, 2013

Tropical Storm Karen is proving resilient in the face of dry air and high wind shear, as the storm heads north-northwest at 10 mph towards Louisiana. A NOAA hurricane hunter plane is in the storm this morning, and found top surface winds near 60 mph and a central pressure of 1001 mb, a pressure 2 mb higher than on Thursday evening. NOAA buoy 42001 located about 60 miles (95 km) north-northeast of the center reported a sustained wind of 38 mph, gusting to 49 mph, at 8:45 am EDT. Satellite loops show that Karen has maintained a vigorous circulation this morning in the face of high wind shear of 25 knots from strong upper-level winds out of the west. These winds have driven dry air from the Western Gulf of Mexico into Karen's core, making it difficult for heavy thunderstorms to build on the west and south sides of Karen's center of circulation. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, and ocean temperatures are a very warm 29°C (84°F). Ocean heat content is 20 - 40 kJ per square centimeter, which is fairly typical for this time of year, and does not increase the odds of rapid intensification. Strong southeasterly winds ahead of Karen are pushing tides about 1 - 1.5' above normal along most of the Louisiana and Mississippi coast, as seen on our wundermap with the storm surge layer turned on.


Figure 1. MODIS satellite image of Tropical Storm Karen, taken at approximately 3:30 pm EDT on October 3, 2013. At the time, Karen had top winds of 65 mph. Image credit: NASA.


Figure 2. Brooding clouds from Tropical Storm Karen hover over the waters offshore of Cancun, Mexico, at 11 am EDT October 3, 2013. Image credit: Mindy Saylor.

Forecast for Karen
Wind shear for the next three days is expected to stay high, around 20 - 30 knots, according to the 8 am EDT SHIPS model forecast. The atmosphere is quite dry over the Western Gulf of Mexico, and this dry air combined with high wind shear will retard development, making only slow intensification possible until landfall. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will bring higher wind shear near 30 knots and turn Karen more to the northeast as it approaches the coast on Saturday. The higher shear, combined with ocean temperatures that will drop to 28°C, may be able to induce weakening, and NHC has sharply reduced its odds of Karen achieving hurricane strength. The 5 am EDT Friday wind probability forecast from NHC put Karen's best chance of becoming a hurricane as a 23% chance on Sunday at 2 am EDT. This is down from the 41% odds given in Thursday afternoon's forecast. Most of the models show Karen intensifying by 5 - 10 mb on Saturday afternoon and evening as the storm nears the coast, as the storm interacts with the trough of low pressure turning it to the northeast. This predicted intensification may be because of stronger upper-level outflow developing (due to diverging winds aloft sucking up more air from the surface.) We don't have much skill making hurricane intensity forecasts, so I wouldn't be surprised to see Karen do the opposite of what the models predict, and decay to a weak tropical storm just before landfall, due to strong wind shear. In any case, residents of New Orleans should feel confident that their levee system will easily withstand any storm surge Karen may generate, as rapid intensification of Karen to a Category 3 or stronger hurricane has a only a minuscule probability of occurring (1% chance in the latest NHC forecast.)

Since Karen is expected to make a sharp course change to the northeast near the time it approaches the south coast of Louisiana, the models show a wide range of possible landfall locations. The European and UKMET models are the farthest west, with a landfall occurring west of New Orleans. The GFS model is at the opposite extreme, showing a landfall about 400 miles to the east, near Apalachicola, Florida. NHC is splitting the difference between these extremes, which is a reasonable compromise. Most of Karen's heavy thunderstorms will be displaced to the east by high wind shear when the storm makes landfall, and there will likely be relatively low rainfall totals of 1 - 3" to the immediate west of where the center. Much higher rainfall totals of 4 - 8" can be expected to the east. NHC's 5 am EDT Friday wind probability forecast shows the highest odds of tropical storm-force winds to be at the tip of the Mississippi River at Buras, Louisiana: 66%. New Orleans, Gulfport, Mobile, and Pensacola have odds ranging from 47% - 51%.

Most significant fire threat for Southern California in the past 5 years
A Santa Ana wind event is building over Southern California this morning, where wind gusts in excess of 50 mph have already been observed this morning. From the Los Angeles NWS office:

"Most significant fire weather threat across Southern California in past 5 years as strong Santa Ana wind event unfolds. In addition to the strength of winds being projected...the concerns with this event include the widespread nature and long duration of Santa Ana winds...very long period of single digit humidities...and extremely dry fuels approaching record levels. Red flag warnings are in effect for much of Los Angeles and Ventura counties overnight into Sunday. The onset of the offshore winds are expected to begin across the mountains by late evening...then descend into the lower elevations overnight. The peak of this Santa Ana wind event will likely be late tonight through Saturday morning...with the strongest winds focused across Los Angeles and Ventura counties."


Figure 3. A moderate risk for severe weather is predicted for this afternoon over Iowa and surrounding states.

A blizzard and a severe weather outbreak in the Midwest
The same low pressure system that is expected to turn Tropical Storm Karen to the northeast this weekend is hammering the Midwest with a variety of extreme weather today. Blizzard warnings are flying in Wyoming, Nebraska, and South Dakota from the storm, and a significant outbreak of severe thunderstorms with a few tornadoes is expected over much of Iowa this afternoon. Wunderground weather historian Christopher C. Burt has done some research to see the last time a blizzard, major severe weather outbreak, tropical storm, and extreme fire danger all threatened the U.S. at the same time, and has not been able to find such an event in past history.

Portlight disaster relief charity ready to respond to Karen
The Portlight.org disaster relief charity, founded and staffed by members of the wunderground community, are ready to respond to Tropical Storm Karen, if they are needed. You can check out their progress on the Portlight Blog or donate to Portlight's disaster relief fund at the portlight.org website.

I'll have a new post this afternoon.

Jeff Masters

Hurricane Karen Atlas

Karen Having Trouble With Dry Air and High Wind Shear

By: JeffMasters, 8:25 PM GMT on October 03, 2013

Tropical Storm Karen is having trouble with dry air and high wind shear as the storm heads north-northwest at 12 mph into the Gulf of Mexico. An Air Force hurricane hunter plane is in the storm, and found top surface winds near 65 mph between 3:30 - 4:30 pm EDT Thursday, and a central pressure of 999 mb, 5 mb lower than this morning's. Satellite loops show that Karen is a medium-sized storm whose heavy thunderstorms have declined in intensity and areal coverage since this morning. The heavy thunderstorms are all on the northern and eastern flanks of the storm, and the low-level center is exposed to view. High wind shear of 20 knots, due to strong upper-level winds out of the west-southwest, is driving dry air from the Western Gulf of Mexico into Karen's core. Heavy thunderstorms are having difficulty building on the west and south sides of Karen's center of circulation because of the shear, resulting in a lopsided comma-shape on satellite imagery. Karen is attempting to build an eyewall, and has managed to wrap a band of heavy thunderstorm about half way around its center. If this band wraps all the way around, Karen will likely be able to intensify into a Category 1 hurricane. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, and ocean temperatures are a very warm 29°C (84°F). Ocean heat content is about 30 kJ per square centimeter, which is fairly typical for this time of year, and does not increase the odds of rapid intensification. Strong southeasterly winds ahead of Karen are already pushing tides 1 - 1.5' above normal along the coast from Eastern Louisiana to Alabama, as seen on our wundermap with the storm surge layer turned on.


Figure 1. Predicted 3-day rainfall totals for Karen, generated at 3:14 pm EDT Thursday October 3, 2013. NHC now puts this product on their website.


Figure 2. Ocean heat content (also called the Tropical Cyclone Heat Potential, TCHP) for October 3, 2013, along the path of Tropical Storm Karen, was about 20 - 40 kJ per square centimeter. This is a fairly ocean heat content for this time of year, and does not increase the odds of rapid intensification. TCHP values above about 75 kJ per square centimeter are typically associated with rapid intensification. Image credit: NOAA/RAMMB.

Forecast for Karen
Wind shear is expected to increase as the storm heads north-northwest, and shear will be quite high, 25 knots, on Saturday, as Karen closes in on the U.S. Gulf Coast, according to the 2 pm EDT SHIPS model forecast. The atmosphere will grow drier as Karen moves into the Northern Gulf of Mexico, and the drier air combined with increasing wind shear will retard development, making only slow intensification likely through Friday. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn Karen more to the northeast as it approaches the coast on Saturday. The higher shear, combined with ocean temperatures that will drop to 28°C, should be able to induce weakening, and the 5 pm EDT Thursday wind probability forecast from NHC gave a 23% chance Karen will be a hurricane at 2 pm EDT Saturday, down from 41% odds at 2 am EDT Saturday.

The models are split into two camps for Karen's track. The European, UKMET, and GFDL models have Karen making landfall over Central or Eastern Louisiana. These models keep Karen relatively weak, resulting in a path that follows the low-level winds more to the west, where there is more dry air and higher wind shear. The GFS model and HWRF model keep Karen stronger, and predict a landfall in the Western Florida Panhandle. NHC is splitting the difference between these two solutions, which is a reasonable compromise. Most of Karen's heavy thunderstorms will be displaced to the east by high wind shear when the storm makes landfall, and there will likely be relatively low rainfall totals of 1 - 3" to the immediate west of where the center. Much higher rainfall totals of 4 - 8" can be expected to the east. To judge the possibilities of receiving tropical storm-force winds at your location, I recommend using the NHC wind probability forecast. The highest odds of tropical storm-force winds (44 - 66%), according to NHC's 5 pm EDT Thursday forecast, are along the coast from Buras, Louisiana, to Pensacola, Florida.


Figure 3. A possible analogue for Karen: Hurricane Ida of 2009 followed a path very similar to Karen's, and was a hurricane just south of Louisiana before suddenly weakening to an extratropical storm with 40 - 50 mph winds as it made landfall in Alabama.

A possible analogue for Karen: Hurricane Ida of 2009
We have little skill forecasting intensity, and I expect that at landfall, Karen has a 20% probability of being a Category 1 hurricane with 75 - 85 mph winds, and a 20% chance of being a minimal tropical storm with 40 - 45 mph winds. One possible scenario is a repeat of what happened with Hurricane Ida of 2009. Ida took a track very similar to Karen's, and was a hurricane with 75 mph winds just south of the mouth of the Mississippi River in Louisiana. High wind shear from an approaching trough of low pressure, combined with cooler ocean temperatures near shore, combined to cause a sudden weakening of the storm. Ida became extratropical a few hours before making landfall on the Alabama coast, and brought top sustained winds of 40 - 50 mph to the coast from Shell Beach, Louisiana to Waveland, Mississippi.

Jeff Masters

Hurricane

Tropical Storm Karen Forms in the Gulf of Mexico

By: JeffMasters, 2:09 PM GMT on October 03, 2013

Hurricane Watches are flying along the U.S. Gulf Coast as Tropical Storm Karen heads north-northwest into the Gulf of Mexico. Karen, the eleventh named storm of the 2013 Atlantic hurricane season, formed about 8 am EDT Thursday in the Southeast Gulf of Mexico. It's not often that one sees a new storm start out with 60 mph sustained winds, but that's what an Air Force hurricane hunter plane found this morning near 7:30 am EDT, when they sampled the northern portion of the storm. A ship located about 50 miles northeast of the northeast tip of the Yucatan Peninsula measured sustained winds of 51 mph near the same time. Satellite loops show that Karen is a medium-sized storm with an area of very intense thunderstorms along its northern and eastern flanks. Wind shear has risen since Wednesday, and is now a moderately high 20 knots, thanks to strong upper-level winds out of the west-southwest. These strong winds are keeping any heavy thunderstorms from developing on the west side of Karen's center of circulation, by driving dry air that is over the Yucatan Peninsula and Western Gulf of Mexico into Karen's core. As a result, Karen has a lopsided comma-shape on satellite imagery. Karen has a strong upper-level outflow channel to its north that is helping ventilate the storm, though, and ocean temperatures are a very warm 29°C (84°F). Between 7 am and 9:30 am EDT the Hurricane Hunters made three passes though the center of Karen, and the central pressure stayed roughly constant at 1004 mb, so Karen is not undergoing much change.


Figure 1. Odds of receiving more than 4" of rain over a five-day period beginning at 2 am EDT Thursday October 3, 2013, as predicted by the experimental GFDL ensemble model.

Forecast for Karen
Wind shear will steadily increase as the storm heads north-northwest, and shear will reach a high 25 knots by Saturday morning as Karen closes in on the U.S. Gulf Coast, according to the latest SHIPS model forecast. The atmosphere will grow drier as Karen moves into the Northern Gulf of Mexico, and the drier air combined with increasing wind shear will retard development, making only slow intensification likely through Friday. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn Karen more to the northeast as it approaches the coast on Friday evening and Saturday morning. The higher shear at that time should be able to induce weakening, and the 8 am EDT Thursday wind probability forecast from NHC gave a 28% chance Karen will be a hurricane at 2 am EDT Saturday, down from 44% on Friday afternoon. Most of the models predict landfall will occur along the western Florida Panhandle Saturday afternoon or evening. The usually reliable European model has Karen making landfall over Eastern Louisiana, though. If Karen does follow this more westerly path, the storm will be weaker, since there is more dry air and higher wind shear to the west. Since almost all of Karen's heavy thunderstorms will be displaced to the east by high wind shear, there will be relatively low rainfall totals of 1 - 3" to the immediate west of where the center makes landfall. Much higher rainfall totals of 4 - 8" can be expected to the east. To judge the possibilities of receiving tropical storm-force winds at your location, I recommend using the NHC wind probability forecast. The highest odds of tropical storm-force winds (45 - 55%) are along the coast from Buras, Louisiana, to Pensacola, Florida.

I'll have a new post this afternoon.

Jeff Masters

Hurricane

97L in Western Caribbean Still a Threat to Develop

By: JeffMasters, 1:58 PM GMT on October 02, 2013

A tropical disturbance (Invest 97L) over the Western Caribbean is moving to the northwest at 10 mph and is generating heavy rains over the Cayman Islands and Western Cuba. Grand Cayman Island had picked up 2.32" (59 mm) of rain as of 9:30 am EDT on Wednesday. Satellite loops show that 97L has a modest area of heavy thunderstorms that have increased substantially in areal coverage and in intensity since Tuesday, but there is little rotation apparent. Cayman Islands radar also does not show any rotation to the echoes, but there are several prominent low-level bands of heavy rain. The storm has low wind shear of 5 - 10 knots to work with, as well as an upper-air anticyclone aloft that is providing good ventilation above it. Dry air is over the Yucatan Peninsula and Gulf of Mexico, as seen on water vapor satellite loops, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F). An Air Force hurricane hunter flight is scheduled for Wednesday afternoon.


Figure 1. Wind forecast for 2 pm EDT Saturday October 5, 2013, from runs of the GFS model done six hours apart. The more recent run, initialized at 06Z (2 am EDT) on Wednesday, October 2 (left panel) predicts that 97L will have top winds below 35 knots (40 mph, light orange colors). This run showed the center of 97L making landfall in the Florida Panhandle about 120 miles east of Alabama late Saturday afternoon.The run initialized six hours earlier, at 00Z (right panel), showed a stronger storm, with top winds of 40 - 45 knots (46 - 52 mph.) This run showed the center of 97L making landfall near the Alabama/Florida border Saturday night. The images were generated using our wundermap with the model layer turned on.

Forecast for 97L: development into at least a tropical depression likely
Wind shear is expected to remain low on Wednesday, then steadily increase to the moderate range on Thursday, then to the high range on Friday, according to the latest SHIPS model forecast. On Wednesday night, 97L will cross the northeastern tip of Mexico's Yucatan Peninsula, bringing 3 - 6" of rain to the peninsula and to Western Cuba. Passage over the Yucatan will act to disrupt the storm. The atmosphere will grow drier as 97L moves northwards over the Gulf of Mexico on Thursday and Friday, and the drier air combined with increasing wind shear will retard development, making rapid intensification unlikely. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn 97L more to the northeast as it approaches the coast on Friday. The GFS model develops 97L into a tropical storm, and predicts landfall will occur along the Florida Panhandle. The European model, which does not develop 97L into a tropical storm, is farther west, taking the storm over Eastern Louisiana. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 40%, and 5-day odds of 50%. I give a 30% chance 97L will be Tropical Storm Karen with top winds of 40 - 60 mph at landfall between Louisiana and the Florida Panhandle on Saturday, a 5% chance it will be stronger, and a 65% chance it will be a tropical depression or mere tropical disturbance. Heavy rains of 3 - 6" can be expected falling the coast from Louisiana to the Florida Panhandle on Saturday, even if 97L does not develop into a tropical depression.


Figure 2. MODIS satellite image of 97L, taken at 12:30 pm EDT on October 2, 2013. Image credit: NASA.

Tropical Storm Jerry in the Central Atlantic no threat
Tropical Storm Jerry continues to slowly wander over the Central Atlantic, far from land. Jerry is not a threat to any land areas.

Jeff Masters

Hurricane

97L Growing More Organized in Western Caribbean

By: JeffMasters, 2:49 PM GMT on October 01, 2013

A tropical disturbance (Invest 97L) over the Western Caribbean is moving to the northwest at 10 mph and is generating heavy rains over Jamaica and the Cayman Islands. Kingston, Jamaica picked up 2.60" of rain on Monday. Satellite loops show that 97L has a modest area of heavy thunderstorms that have increased in intensity and organization Tuesday morning. The broad area of spin associated with 97L is growing more defined, and the storm is taking advantage of wind shear that has fallen to the low range, 5 - 10 knots, as well as an upper-air anticyclone that has set up over the storm, providing good ventilation aloft. Dry air covers the Northwest Caribbean, as seen on water vapor satellite loops, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F). A hurricane hunter flight scheduled for Tuesday afternoon was cancelled due to 97L's lack of organization, and has been rescheduled for Wednesday.


Figure 1. Latest satellite image of Invest 97L.

Forecast for 97L: development into at least a tropical depression likely
WInd shear is expected to remain low to moderate through Friday, according to the latest SHIPS model forecast. The lack of wind shear on Tuesday and Wednesday should allow 97L to moisten the atmosphere and wall off the dry air to its northwest that is slowing down development, and I expect 97L will be close to tropical depression status by Wednesday morning. By Wednesday night, 97L will cross the northeastern tip of Mexico's Yucatan Peninsula, bringing 4 - 8" of rain to the peninsula and to Western Cuba. Passage over the Yucatan will act to disrupt the storm. The atmosphere will grow drier and wind shear will increase as 97L moves northwards over the Gulf of Mexico on Thursday and Friday, and these combined effects will likely retard development. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn 97L more to the northeast as it approaches the coast on Friday. The GFS model predicts landfall will occur along the Florida Panhandle, while the European model is farther west, taking the storm over Eastern Louisiana. Neither model shows 97L developing tropical storm-force winds. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 30%, and 5-day odds of 50%. I give a 40% chance 97L will be Tropical Storm Karen with top winds of 40 - 60 mph at landfall between Louisiana and the Florida Panhandle on Friday night, a 10% chance it will be stronger, and a 50% chance it will be a tropical depression or mere tropical disturbance.


Figure 2. MODIS satellite image of Jerry, taken at 10:30 am EDT on October 1, 2013. Image credit: NASA.

Tropical Storm Jerry in the Central Atlantic no threat
Tropical Storm Jerry formed on Monday in the Central Atlantic, far from land. Jerry is the tenth named storm of the 2013 Atlantic hurricane season, and arrived twenty days before the usual appearance of the season's tenth named storm, which is October 19. Jerry is not a threat to any land areas.

Jeff Masters

Hurricane


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