moonlightcowboy's WunderBlog

DAMAGE REPORTS from Felix

By: moonlightcowboy, 2:05 AM GMT on September 01, 2007

These reports in the posts below were taken from a variety of sources...best I could do this evening. I think when the wind and rain subsides, the storm is going to be absolutely devastating. Much of what I found was in Spanish and I had to take it to babelfish for translation.

Hopefully, at least, loss of life will be at a minimum. One official there seemd pleased with the results from their alert system. Maybe, that will translate into little loss of life, and certainly NOTHING like Mitch.

...my apologies to the blog earlier this evening. I'd been busy all day with work without a chance to check in, so I was a bit anxious to hear some news after work. It bothered me as I noted that all I was seeing was just posts about the next possible storm, and it appeared that we'd already forgotten Felix.

I supposed my angst piqued with my post this morning:
Posted By: moonlightcowboy at 10:11 AM GMT on September 04, 2007.
Waked up this morning, watching ABC's "America This Morning" and they mention "Henriet" in detail, but ABSOLUTELY NO mention of Felix. Couldn't believe it! Here we have history being made with two Cat 5 landfalling storms back-to-back, in a situation where there is likely to be considerable loss of life and property, and they DON'T EVEN MENTION IT! Wow!


I know now that was not the case, and that information is just slow to get out of the region. Much respect, to everyone, and again my apologies! Thanks!



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"Awareness, preparedness and safety" is everything!
Your comments and suggestions are welcome. Thanks in advance! Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!

94L, some dry air, but will develop....

By: moonlightcowboy, 3:03 AM GMT on August 27, 2007

94L is on its way! I don't think it'll cross the islands as strong as Dean, and I also think it'll find a more northerly track before the high pushes back in. But, it sure looks like we're going to get another named storm, probably Gabrielle, if 96L becomes Felix later this evening or tomorrow.

Thumbnail
Latest NAVY MicroVAP. This TWP shot shows that there is more moisture available than is immediately seen. Look at the "dark" areas now around 94L which means that the storm has become better organized, producing more moisture and creating a better development environment.

Missing
CURRENT MID LEVELS WATER VAPOR
Here's the current view of water vapor at the mid levels from the cimss. It's gaining a little momentum in development because there's more moisture available to the system than immediately visible. While 94L is getting some dry/dusty air entrainment, it continues slowly strengthen and track westwards with better development conditions. It's also more likely to make more of a wnw turn as it becomes stronger.

94L is more likely to enter the eCarib as a TD or a weak TS. On development: faster and stronger = more northerly, while slower and weaker = more westwards. Still low development for sure, right now; but, I still believe it will become a named storm, probably Gabrielle if 96L becomes Felix later this evening, or tomorrow.

Another look at dry, stable air. While there is dry aire you can see that area wnw of 94L that is clearing the way for more favorable development conditions for 94L.

http://www.nhc.noaa.gov/tafb_latest/atlsfc48_latestBW_sm3.gif48 HOUR SURFACE FORECAST MAP The low between the Gulf high and the Atlantic high is a key player right now (IMHO) getting stronger, stretching deeper southwards. Any development, though slow, would still likely track like Dean with the high being slower to build back in, and taking a more wnw turn after passing through the islands. I don't look for any real strengthening until it gets closer to the islands, and at this time more than likely somewhere just south of Dean's track. That, however, is likely to change to a more northerly track, especially if the high doesn't build back in as strong like it did with Dean.

The image http://www.nhc.noaa.gov/tafb_latest/atlsfc72_latestBW_sm3.gif cannot be displayed, because it contains errors.
72 HOUR SURFACE FORECAST MAP SFC map shows 94L as a possible tropical cyclone after it enters the eCarib. Of course, things can change in the tropics on a dime. Lots of things going on right now and the wave in the eATL looks to be serious, too.

Tropical - GOES-East IR 4 Floater
Tropical Latest Image - GOES-East IR 4 Floater #1


[GOES-12 14 km WV]
RAMSDIS 14 km Water Vapor

http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2007238ca.jpg

The TCHP values are still high in the nw Caribbean away from Dean's track. In fact, the nw and nCarib waters may have gotten a little warmer and extended its stretch up to the Yucatan channel. So, while Dean did some damage as Doc Master's points out in his current blog, there is still a great deal of hot waters and high TCHP in the eCarib and the GOM, too.

Missing
LATEST STEERING CURRENTS


CURRENT DUST LOOPS

There are several links to SAL, but EUMETSAT is my favorite. For me it shows a more true, actual view of the dust which is in pink. The links also show airmass and fog. These views appear to be "dimensional" and while SAL mostly occurs at the surface or low levels, if you'll take a look, it also shows orange and red, depicting a look at mid and upper level convection. For me this is a good first way to look at the layers of any developing CV storm.

EUMETSAT (dust angle 1)
EUMETSAT (dust angle 2)
REAL-TIME SAL satellite imagery for tracking can be found here, too.


Latest Surface Map

The National Buoy Center
850mb Vorticity
Wind Shear
24hr shear tendency
GOM/Caribbean Sea Surface Temps
Latest TWO
Latest NHC Tropical Weather Discussion


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LATEST NAVY MICROVAP

Missing
CURRENT MID LEVELS WATER VAPOR
Here's the current view of water vapor at the mid levels from the cimss.

http://www.ssd.noaa.gov/met8/eatl/ir2-l.jpg
Latest Infrared Shortwave in the eATL


MLCgoodnight4.gif

"Awareness, preparedness and safety" is everything!
Your comments and suggestions are welcome. Thanks in advance! Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!

Metropicalis blown away by ULL!

By: moonlightcowboy, 11:37 PM GMT on August 22, 2007

The image http://shum.cc.huji.ac.il/~luski/images/superman_logo.jpg cannot be displayed, because it contains errors.

It's bird. It's a plane. It must be a hurricane!!! Nope, it's just a spinning ULL! CLARKE KENT COULD STOP A SPEEDING BULLET -- BUT, A TRICKY ULL IS ANOTHER STORY, and a serious "forecasting" factor in Metropicalis!

051106_IR.JPG

ULL (Upper Level Low) is an area of cold air aloft (20,000 to 30,000 feet) that is rotating counter-clockwise. These sometimes steer hurricanes and less frequently, transform into a warm core low and work their way down to the surface to become a tropical cyclone. You can see this large upper level low over the mid-western US in the above photo. Sure looks kind of like a hurricane, doesn't it!

http://personalhurricanecenter.com/wp-content/uploads/2007/08/dean-wv-08-19-07-12.jpg

THE ULL AND DEAN
-- We all watched Dean track through the Caribbean...and it kept going west and then west and then west! Of course the main reason for that was the high over the CONUS ridging southeastwards behind Dean driving it westwards. But, what about that ULL (center GOM) many thought could change Dean's track?

Many suspected Dean might catch the trail of the ULL that was spinning and moving west in the GOM and steer the storm on a more northwards course. Obviously, that didn't happen. The ULL moved on westwards as the high kept building back in behind Dean. It then moved on west to the Yucatan, just side-swiping Jamaica and staying south of the Caymans.

However, (as they say) "if" a few things had happened Dean may have taken a more northerly course. Jamaica could possibly have taken a direct hit, then passed over the Caymans on its way into the GOM. Had the high not ridged so much and the ULL been slower, deeper or further south, we may have been seeing a central GOM coast landfall. Some of the early model runs including the GFDL at one time suggested just that scenario.

So, I thought I'd blog this time on the ULL. After reading, maybe we'll have a somewhat better understanding of the ULL and what it means in forecasting! Perhaps even, it may give us a better understanding of how it effects modeling tracks. Unlike the high SST's, the ULL is generally in a state of flux. Either strengthening or weakening; and, unless stationary, moving too. So, it makes sense that the ULL is quite a difficult and "variable" factor in forecasting. And no doubt, critical.

DEAN's Forecast Track: Despite an early northwards projection from some of the models, most eventually became congruent to take the low west, followed a few days behind by Hurricane Dean. The tracking of this upper-level low gave forecasters enough time to monitor any changes in the speed of the low, and thus correctly make changes to their forecast.

With past storms, the situation is generally the same. In most cases, instead of an upper-level low moving west across the Gulf, its a building trough coming in from the western United States. Typically, as in the cases of Hurricanes Ivan, Isidore, Katrina and Rita, the westward moving hurricanes find the western edge of the breaking-down high and begin their turn north. Had Dean been just a little further west of its location, a landfalling hurricane in the northwestern Gulf of Mexico may have been possible.

Of course, it was all about timing. Any slight delay or advance of that turn compounded by the degree of the turn can make even a reasonably-accurate forecast off by several dozen miles. These changes compound quickly as a storm progresses, especially in areas such as the GOM, or the Mid-Atlantic. A slight change in direction by a hurricane can throw the forecasted landfalls off by as much as 200 miles.



The image http://upload.wikimedia.org/wikipedia/commons/6/64/Hurricane_Bill_%281997%29.JPG cannot be displayed, because it contains errors.
- In 1997 HURRICANE BILL developed from a non-tropical upper level low above Puerto Rico. Though infrequent a ULL can work its way down to the surface and become tropical.

HURRICANE BILL and how it formed from a ULL.
Bill developed from a large upper-level low that separated from the mid-oceanic trough northeast of Puerto Rico. On 7 July, satellite images indicate that cloudiness and showers associated with the upper- level low began to increase and although surface pressures were quite high north of Puerto Rico there was a small perturbation of the wind field and a trough at the surface. A low pressure center formed from the trough just east of the Bahamas and moved toward the west-northwest. The upper-level low moved southwestward into the Caribbean Sea resulting in a decrease in the wind shear over the surface low.

The first indications that a tropical depression might be forming was a 24-hour pressure drop of near 3 mb in the eastern Bahamas as the area of low pressure approached. Convection then gradually became organized and it is estimated that a tropical depression formed near 0600 UTC 11 July. By then, the tropical cyclone was already moving northeastward ahead of a cold front located over the eastern United States. The system reached tropical storm status by 1200 UTC on the same day.

Bill continued moving toward the northeast about 20 to 25 knots and reached cool waters. An eye was depicted on high resolution visible images at 1300 UTC 12 July, suggesting that Bill reached hurricane strength in spite of the cool waters. A special Dvorak classification from the Tropical Analysis and Forecast Branch (TAFB) indicated that Bill reached its peak intensity of 65 knots at 1500 UTC 12 July. The minimum pressure estimated at that time was 986 mb. Thereafter, Bill became absorbed by a frontal system and was no longer identifiable by 0600 UTC 13 July. Bill was never forecast to become a hurricane.


IMPORTANT TO FORECASTING: Upper level lows are important to forecasting and can dramatically alter one's forecast. Upper level lows can occur in association with a mid-latitude cyclone or may begin without the aid of a mid-latitude cyclone. Upper level lows without the aid of a surface low can develop when air flows over a mountain range, in association with an upper level short wave, or in association with a jet streak.

COMMON PATTERNS:
When analyzing a strong mid-latitude cyclone, some common patterns can be noticed. One is that the trough associated with a mid-latitude cyclone tilts toward the cold air (generally tilts to the northwest with height). Therefore, the upper level low pressure (trough) in association with a mid-latitude cyclone may be several 100 kilometers displaced from the surface low toward the west or northwest. Since the forecast models have a more difficult time initializing an upper level low than a surface low, upper level lows can result in a busted forecast. The forecast models have a better vertical resolution of the low levels of the troposphere as compared to the upper levels. In some mid-latitude cyclones, the tilt of the mid-latitude cyclone will be enough to allow the upper level low to displace from the surface low.

WHAT CAUSES AN UPPER LEVEL LOW? An upper level low is a region of positive vorticity. This positive vorticity can be caused by counterclockwise curvature around the upper level trough and counterclockwise shear associated with the speed shear of a jet streak. The circulation around an upper level low can build to the surface over time. In these cases, two areas of low pressure will be noticed on the surface chart. These are sometimes referred to as double-barrel low-pressure systems. Upper level lows can also decrease in intensity through time.

A HUGE FORECASTING PROBLEM
is determining whether an upper level low will strengthen or weaken with time. When nowcasting, they are best viewed on satellite imagery. Image by image they should be monitored for intensity. When the clouds brighten (become whiter) in association with the upper level low, that is an indication the upper level low is strengthening.

BEST SEEN:
If an upper level low does show on the analysis or forecast models it is best seen at the 500 millibar level or 700 millibar level. Upper level lows have been responsible for bringing unexpected heavy snows in the winter. The spin-up of vorticity in an upper level low causes the air to rise and cool. Since the upper level low is tilted over the cold air, cold surface temperatures and upper level lifting combine to produce wintry precipitation well behind (to the west or northwest) or the surface cold front. When a mid-latitude cyclone begins to mature, watch for the development of the upper level low.

"Looks like the gates to the fort are open now!"

MLCgoodnight4.gif

"Awareness, preparedness and safety" is everything!
Your comments and suggestions are welcome. Thanks in advance! Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!


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CAT 5 Dean to hit Yucatan

By: moonlightcowboy, 3:45 PM GMT on August 14, 2007

IMPORTANT TROPICAL NOTICE! I wanted this blog to first address awareness, preparedness and safety! These things are important NOW, not when landfall is a couple of hours away! I hope you'll see it that way, too, and click on the two links below. Please take time to review them and I believe it will be very helpful.

HyperText Transfer Protocol
CLICK ON THIS LINK...you'll be glad you did! http://www.redcross.org/beredcrossready


Hopefully, through "awareness and preparedness" there will be little injury and loss of life. Even the threat of a storm causes much anxiety for many. That, in itself is destructive, even without a landfall! Despite all the damage that may occur to property, let's all hope that we're doing what we can to help prevent harm and death to people in harm's way.

Get a plan, if you don't have one! Take it seriously. Develop a plan for yourself. Have a plan "B" and be ready to execute them. Talk with your neighbors. Call your friends and relatives and discuss it with them if you can. Remember the elderly, indigent and handicapped. Remind them all of safety precautions and evacuation plans. Have a destination and a second possible destination.

Exchange plans, numbers and destinations. Ask others to pass the "safety" word around. Of course, local authorities will be the best resource for information and action plans. Listen to them and encourage others to listen as well. Visit Patrap's Blog, a great guy who believes in promoting preparedness and safety. Also, another good one is Hurricanecrab's Blog. These small efforts can have a large effect on the safety of peoples lives. You can make a difference!

The Tropical Weather Discussion from the NHC is a great place to start to get solid information. It basically, "tells it like it is" without all the hubbup!

HURRICANE DEAN (WU quick links) is out in the wCaribbean traveling west and is NOW a MAJOR CAT 5 hurricane at it approaches the Yucatan peninsula!


http://www.nhc.noaa.gov/tafb_latest/atlsfc24_latestBW_sm3.gifThe 24-HOUR Surface Forecast Map: Dean is an intense CAT 5 hurricane and likely to cause sweeping damage across the peninsula, re-emerging in the Bay of Campeche as a strong hurricane. Then, Dean is likely to intensify again to major hurricane status before making a second landfall on the Mexico mainland. NOTICE: new NAVY INVEST 92L at 24n,60.5w moving wnw. Some development is possible, but it's fairly disorganized, but will be interesting to see how convection may build through the night.

Missing

LATEST STEERING CURRENTS - Dean is still being driven west by the ridging high over the se conus. Dean will come ashore somewhere north of Chetumal as a CAT 5 storm with a huge storm surge upwards of over 30 feet.


GOES WATER VAPOR LOOP


HURRICANE DEAN, now a strong CAT 5 hurricane is expected to make landfall early Tuesday morning on the Yucatan coastline. Dean's center is now at about 18n,85w. Speed is near 20 mph with sustained winds recorded at near 160 mph at the surface and gusting near 180 mph. Surface pressure has dropped to 915 mb and reportedly has tied Hurricane Janet of 1955 as the 10th strongest hurricane ever recorded in the Atlantic basin.

http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2007230ca.jpg


CURRENT TCHP VALUES:
Dean's CAT 5 status is likely caused by the high TCHP values in the nwCaribbean and may intensify further before landfall. The Caribbean's and GOM's hot temps, TCHP and loop eddys are fuel for rapid and dangerous intensification. (TCHP and SST's in the Caribbean and GOM)


models

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I left this up for this blog, because WU shows the GFDL as a featured model on the their site. IMPROVING THE INITIALIZATION OF HURRICANE-OCEAN MODELS - as related to TCHP, is a technical, but interesting read about how the GFDL is being used to improve hurricane intensity prediction in the GOM.


"Looks like the gates to the fort are open now!"

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Drop back in! Things are gonna get rough somewhere, unfortunately. "Awareness, preparedness and safety" is everything!
Your comments and suggestions are welcome. Thanks in advance!
Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!


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TABASCO served in the GOM and 90L is declared!

By: moonlightcowboy, 12:55 AM GMT on August 10, 2007

SPECIAL PRE-TEXT- LOWERCAL's blog has an interesting topic about this weekend's "meteor shower" and some great links to space shuttle Endeavor's current mission. Check it out!

NOW, ON TO THE TROPICS!

SSTs3.gif picture by moonlightcowboy

Gulf Waters Are "TABASCO" Hot!
Metaphorically, the GOM is just that hot! And, if you've ever dined in a southern restaurant, one knows that the little bottle of fire that sits on the table is legendary because of its heat! A friend of mine buys it by the gallon and puts it on nearly everything, including eggs and cole slaw. Of course, I like it, too; but not on everything (lol). It's not too ironic that the fiery product hales from Louisiana almost right on the GOM at Avery Island about a 100 miles west of NOLA.

And while Tabasco can heat up our foods, Gulf waters also heat up our hurricanes! The GOM's hot waters are "pure fuel" for rapid intensification. These storms need two basic ingredients to develop: warm, moist air and a relatively calm atmosphere. The GOM does just that as we saw in 2005 with Katrina. Ocean waters above about 27 degrees Celsius (80 Fahrenheit) give rise to the warm, moist air that fuels tropical storms, and winds that could tear a storm apart are light during the summer. Waters are 86 degrees and warmer now, with much of the GOM even in the 90's. Typically, the GOM's waters are hot even at the beginning of hurricane season, while it generally is August before the Atlantic is primed.

This image above shows sea surface temperatures in the Atlantic, Caribbean and the Gulf of Mexico. Water that is warm enough to fuel hurricanes is yellow, orange, and red. So, as you can see the relatively shallow Gulf of Mexico and the Caribbean are quite hurricane-ready! And, unfortunately, can turn an already bad storm into a monster!
Actual SST link for graphic above.


THE NATIONAL BUOY CENTER - an excellent site for checking on-the-spot GOM and Caribbean SST's, pressure and winds.

http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2007220ca.jpg

TCHP = TROPICAL CYCLONE HEAT POTENTIAL These "boiler" ingredients could create a dangerous situation if a storms tracks through these deep, hot waters which are more serious than the 2005 season.
--- TCHP from Doctor Jeff Master's WU blog on July 16, 2007
It's not just the SSTs that are important for hurricanes, it's also the total amount of heat in the ocean to a depth of about 150 meters. Hurricanes stir up water from down deep due to their high winds, so a shallow layer of warm water isn't as beneficial to a hurricane as a deep one. The Tropical Cyclone Heat Potential (above graphic) is a measure of this total heat content. A high TCHP over 80 is very beneficial to rapid intensification. There is less heat energy available this year than in 2005, which recorded the highest SSTs and TCHP ever measured in the tropical Atlantic. However, this is not true in the Western Caribbean, where we have very high TCHP this year. The African dust storms have not penetrated all the way to the Western Caribbean, and SSTs and TCHP have stayed above average. In the unlikely event we get an intense hurricane in late July, it would probably be in the Western Caribbean.


IMPROVING THE INITIALIZATION OF HURRICANE-OCEAN MODELS - as related to TCHP, is a technical, but interesting read about how the GFDL is being used to improve hurricane intensity prediction in the GOM.


LOOP.gif picture by moonlightcowboy

GOM LOOP CURRENT -- The clockwise flow that extends northward into the Gulf of Mexico and joins the Yucatan Current and the Florida Current is known as the Loop Current. The Loop Current is variable in position. At one extreme, it has an almost direct path to the Florida Current, causing the shear in the flow to set up a quasi-permanent clockwise recirculation known as the Cuban Vortex. This feature may help initiate Loop Current expansion.

At the other extreme, the Loop Current intrudes into the Gulf of Mexico, forming an intense clockwise flow as far north as 29.1N. Occasionally this loop will reach as high as the Mississippi river delta or the Florida continental shelf. The Loop Current returns to its direct configuration by slowly pinching off its extension to form a large, warm-core ring that then propagates westward at speeds of 2-5 km day.

The Loop Current draws its waters from the Yucatan Current, which is ultimately fed by the Caribbean Current, Guiana Current and North Equatorial Current. Frequencies of ring separation vary and the annual fluctuations in Loop Current flow are apparently due to wind forcing.

Missing

The above figure shows a series of vertical slices of water temperature in the Gulf of Mexico. This sequence is oriented SE to NW so as to capture the warm eddy's "core" structure. (THAT'S LIKE 92 DEGREES!!!) The temperature data used for this analysis was obtained from bathythermographs deployed from NOAA's WP-3D aircraft on 8/3/99. The domain shown extends from the surface to a depth of 500 meters, between 23� and 29� North latitude and 85� to 91� West longitude.

RAPID INTENSIFICATION

The intensification of tropical cyclones involves a combination of different favorable atmospheric conditions such as atmospheric trough interactions and vertical shear, which lead to good outflow conditions aloft. As a result of this, inflow conditions in the near-surface layer are enhanced. Clearly, as this process continues over the scale of the storm, the upper ocean provides the heat to the atmospheric boundary layer and the deepening process. In this scenario, the upper ocean thermal structure has been thought to be a parameter that only played a marginal role in tropical cyclone intensification. However, after a series of events where the sudden intensification of tropical cyclones occurred when their path passed over oceanic warm features, it is now being speculated that it could be otherwise.

While the investigation of the role of these rings and eddies is a topic of research in a very early stage, preliminary results have shown their importance in the intensification of hurricane Opal (Shay et al, 2000). Therefore, the monitoring of the upper ocean thermal structure has become a key element in the study of hurricane-ocean interaction with respect to the prediction of sudden tropical cyclone intensification. These warm features, mainly anticyclonic rings and eddies shed by the Loop Current, are characterized by a deepening of several tens of meters of the isotherms towards their centers and with different temperature and salinity structure than the surrounding waters.

http://www.aoml.noaa.gov/phod/trinanes/HHP/images/HHPOMB.jpg
(1) OPAL (2) MITCH (3) BRET

These storms passed over areas with very high values of TCHP


(1) Hurricane Opal in the Gulf of Mexico, August-September 1995 (left):
This TC intensified from hurricane-1 (74-95 mph winds) to hurricane 4 (131-155 mph winds) while traveling over a number of warm features in the Gulf of Mexico. In particular, this TC suddenly intensified from hurricane-2 (96-110 mph winds) to hurricane-4 in a period of 10 hours when its track went over a very well defined ring with a mean radius of 150 km that had been shed by the Loop Current. Altimeter-derived fields indicate that the increase in TCHP associated with this warm ring was approximately 30 kJ/cm2. The most striking information of the ocean conditions during the life span of this hurricane over the Gulf of Mexico was that this warm ring was not detected using the AVHRR-derived sea surface temperature fields.

(2) Hurricane Mitch in the Caribbean Sea, October 1998 (center):
This cyclone intensified from hurricane 2 to hurricane 5 (winds above 155 mph) when its track traveled over a region of warm surface waters, experiencing an intensification from hurricane 3 (111-130 mph winds) to 5 with an increase in values of TCHP approximately 80 kJ/cm2 under the track of the TC in 22 hours.

(3) Hurricane Bret in the Gulf of Mexico, August 1999 (right):
This hurricane intensified several times in the SW Gulf of Mexico in a period of approximately 36 hours while traveling over two warm features remnants of one warm ring that had been shed by the Loop Current several months earlier. The increase in TCHP under the track of the TC during this period was approximately 80 kJ/cm2.

In these cases an association was observed between the increase in TC intensity and a raise in the value of TCHP under the track of each of the TCs. Preliminary evaluation of the upper ocean thermal conditions during the intensification of 32 of the 36 strongest TCs in the tropical Atlantic from 1993 to 2000 indicates that their intensification can be associated with the passage of their tracks over regions, with increased TCHP of at least 20 kJ/cm2.
(image and comparison-credit NOAH)

Missing
LATEST STEERING CURRENTS

24hr shear tendency

If you look at the graphic below, you'll see that a number of storms develop this time of year in the area just east of the southern islands. That's where the last few invests (except for 98) have tried to get their acts together and I think that's where we'll also see 90L develop from, if it doesn't develop in the Caribbean first.

The chance (percentage) of a named tropical cyclone in August

Tropical Cyclone Probabilities - Named Storms in August
This is the chance at any particular location that a tropical storm or hurricane will affect the area sometime during August. Based on years 1944 to 1999 in the analysis and counted hits when a storm or hurricane was within about 100 miles (165 km). (Figure by Todd Kimberlain.)


Latest TWO
Latest NHC Tropical Weather Discussion
Look here on the Latest Surface Map for the Itcz location, waves, and other surface features.


"IMHO Tropical Summary"

The African wave, now declared 90L is located at around 11n, 20w in the eAtl with winds of 30 mph. Convection seems to building and is looking more circular in appearance. T'storms still have to persist, become more frequent and more intense for more development. It's the most impressive wave off the African coast this year; yet, it still has some things to prove. Surface pressure is at 1006 mb. If that lowers it will help increase convergence. It also now seems to have some rotation and may be developing a low level center.

Most of the models are in agreement for development. And while there is congruency, it's still early to predict actual tropical formation, a specific track, or landfall! Some of them models are in agreement to a northern Antilles track, but that's a long way out, still. The only land it's close to right now is Africa! There will also likely be several track shifts with the models because the wave is so far out. Even with development, any landfall would be a week or more out.

It'll be interesting to see how much convection it builds early with the increased activity in the Itcz and how quickly it's able to get to TD status. There's still some loitering dry air in the cAtl, but not enough to prevent development. Still, I don't think we'll see any real strengthening until it reaches the area between 45w-55w (see the above chart regarding "August named storms). And, that's only if it can hold everything together along the way. Some dry air and upper level shear could be prohibiting factors as it travels westwards at 15-20 mph. We'll know more in the coming hours with current winds reported at 30 mph, it may be on it's way to becoming a TD later this evening.

The Bermuda/Azores high is ridging far enough south that it will keep this wave's convection clinging to the Itcz. That also means that it keeps more of a westward track until it reaches the region of the southern islands. And, a few of the long range forecasts have it moving more towards the southern islands. That's where things will become more serious. There are several warm currents running through the se Caribbean and if a developing storm finds this area, it will quickly find hot waters for fueling intensification. Any track into the nw Caribbean and the GOM almost means "major" hurricane status and will be a serious threat to the northern Caribbean islands, CA, Mexico and the GOM states.

Plus, there is another African wave about ready to take a dip in the Atlantic. And, it's still possible that we could see some Caribbean and other development, too. One thing's for sure, it's getting more active and conditions appear to be overall much better for development.

It's still early and many things can happen. However, it's not too early to be watching and getting a good hurricane plan! Awareness, preparedness and safety is the name of the game. If you don't have a plan get one. Have a Plan B. Visit Patrap's Blog. He's got some "hot tips" about awareness, preparedness and safety! Get things in order before a storm is bearing down on your location. Don't wait! The tropics are definitely heating up! We may get lucky, but the odds aren't stacked that way. This African wave may just be the "Dean" of storms!

"Hold down the fort and keep the gates closed!"


MLCgoodnight4.gif

Your comments and suggestions are welcome. Thanks in advance!
Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!


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Less ITCZ convection! Why?

By: moonlightcowboy, 5:17 AM GMT on August 05, 2007

PLEASE keep in mind, that this is JMHO from listening, reading and observations. It is NOT professional. You should ALWAYS depend on your local authorities for information and instructions! In our short lull this week, I thought I'd blog on the Itcz. What it is and what's happening with one of the driving forces in tropical development. If you see errors, or disagree, please post your thoughts and facts. I appreciate your input, comments and corrections! Thanks!

itczone-2.jpg picture by moonlightcowboy

The Intertropical Convergence Zone (ITCZ) is an area of low pressure that forms where the Northeast Trade Winds meet the Southeast Trade Winds near the earth's equator. As these winds converge, moist air is forced upward. This causes water vapor to condense, or be "squeezed" out, as the air cools and rises, resulting in a band of heavy precipitation around the globe. This band moves seasonally, always being drawn toward the area of most intense solar heating, or warmest surface temperatures. It moves toward the Southern Hemisphere from September through February and reverses direction in preparation for the Northern Hemisphere's summer.

http://www.nhc.noaa.gov/tafb/ATSA_00Z.gif

SURFACE MAP If you click on the above map, and zoom in, it makes it easier to see the location of the Itcz which is the red line that runs across the width of the map. If you'll notice, the Itcz is running lower than 10n in the cAtl which is considerably lower than the mean for this time of year and consequently, there's been less activity. The Itcz has regularly been below 10n with only recent hikes further northward and then, mostly only in the eAtl towards the African coast.

That's unusual for this time of year. It may also be "part" of the reason we haven't seen as much activity. And, I think it could also possibly extend the "peak" of this year's season. Below, in the next few graphic/sat visuals, you can see part of the Itcz is running below 10n. That may also have allowed SAL to be more prevalent and milder eAtl SST's. The Itcz reportedly moves towards the warmer SST's north of the equator around this time of the season and I think that's what we're beginning to see.



http://www.ssd.noaa.gov/goes/east/tatl/rb-l.jpg

GOES EAST RAINBOW IR
If you'll look closely, you can see that what thunderstorm activity there is in the Itcz is mostly running near 10n, especially in the cAtl. Less storm activity in the Itcz consequently also means less favorable development conditions. In my humble opinion, activity has been less than normal, possibly because of the strong B/A High, and maybe partly due to the amount of SAL; or moreover, the stable/dry air. And, especially in the area of the cAtl.



The image http://www.cpc.ncep.noaa.gov/products/fews/ITCZ/west.gif cannot be displayed, because it contains errors.

MEAN POSITION OF THE ITCZ
But, according to the chart, the mean position for the first 10 days in August would be running near 19n (which seems high to me). It is running nearly that high closer to the African coastline and is on the continent. There it seems to be presently running at near mean average. But, it is not in the cATL and further west towards SA.


Mean ITCZ

LATEST (Itcz) TEXT SUMMARY
During the period from July 21 - 31, 2007, the African portion of the ITCZ was located near 19.0 degrees north latitude when averaged over the ten day period and from 15W-35E. This compares with a normal position of 18.2N and a position last year of 17.3N. In the west, from 10W-10E, the ITCZ was located near 19.8 degrees north, compared to the long term mean of around 19.3 degrees north, and a position last year of 18.3N. In the east, from 20E-35E, the ITCZ was located near 18.0N, compared with 16.6N for the mean, and 16.5N for last year. The ITCZ moved north rapidly during the last dekad. It is now positioned at, or above normal across most of Africa.



http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/itcz_goes11_lrg.jpg

GOES PROJECT IMAGE from NASA
This image clearly shows the Itcz running at a considerably higher latitude than it's presently running.


MYSTERY of the ITCZ
What Keeps the ITCZ North of the Equator?

It is a long-standing mystery that the ITCZ stays north of the equator over the Atlantic and eastern Pacific Oceans despite that the annual-mean solar radiation at the top of the atmosphere is symmetric with respect to the equator. This article reviews recent progress that has shed new light on this old puzzle.

(excerpt in part)...The ITCZ problem thus involves a circular chicken-and-egg argument. The ITCZ stays north of the equator because SST is higher; and the SST is higher north because the ITCZ stays there. The positive WES feedback is at the center of this circular argument. In a coupled ocean-atmosphere model, the WES feedback destabilizes the symmetric climate, leading to an asymmetric steady state with a single ITCZ on only one side of the equator (Xie and Philander 1994). A condition for this spontaneous development of latitudinal asymmetry is the equatorial upwelling that prevents the ITCZ from forming at the equator. This necessary condition thus explain why climatic asymmetry only develops over the eastern Pacific and Atlantic where the equatorial upwelling is observed.
(Complete article here.)

Heavier precipitation occurring over warmer waters


ITCZ SUMMARY

In recent days the Itcz seems to be moving further north, despite it's day to day flucuations n and s. Presently, it has dipped down again in the cAtl at around or below 10n. There's been less activity and with the amount of dry air that we've seen, all of the waves thus far have been dependent on moisture from the Itcz. That's why (IMO) there's been less Atlantic activity. As it moves further north for the Cape Verde season, we can expect more activity and more opportunities for tropical waves to organize and produce spinning storms. A more northerly Itcz makes it easier for developing storms to coriolis. And, more Itcz moisture further north also weakens SAL and dry/stable air, making conditions more favorable.

Look here on the Latest Surface Map for the Itcz location, waves, and other surface features.

-----------------------

OTHER LINKS, SATS, AND GRAPHS:

[GOES-12 14 km WV]
RAMSDIS 14 km Water Vapor
Dust is not really a factor in the cATL or the Caribbean, but dry air still is. There's a new pocket of dry air that has made its way down into the cAtl at the sfc level and some dry air also still lingers at the sfc level in the central and north Caribbean. But, that can change fairly quickly as 99L demonstrated that a developing storm can survive despite dry air entrainment. Again, the Itcz moving northwards should also relax the dry air making it less of a prohibiter.

http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2007215ca.jpg
TCHP These "boiler" ingredients could create a dangerous situation if a storms tracks through these deep, hot waters which are more serious than the 2005 season.

***NEW FEATURE***Current GOM Loop Eddys Click to enlarge.


Missing
LATEST STEERING CURRENTS


CURRENT DUST LOOPS

There are several links to SAL, but EUMETSAT is my favorite. For me it shows a more true, actual view of the dust which is in pink. These links also show airmass and fog. Views appear to be "dimensional" and while SAL mostly occurs at the surface or low levels, if you'll take a look, it also shows orange and red, depicting a look at mid and upper level convection. For me this is a good first way to look at the layers of any developing CV storm.

EUMETSAT (dust angle 1)
EUMETSAT (dust angle 2)
EUMETSAT (dust angle 3)

REAL-TIME SAL satellite imagery for tracking can be found here, too.

The National Buoy Center


MODELS and SHEAR

GFS 850 Vorticity
GFS 850-200mb Shear
24hr shear tendency

Missing
CURRENT MID LEVELS WATER VAPOR

http://www.ssd.noaa.gov/met8/eatl/ir2-l.jpg
Latest Infrared Shortwave in the eATL


Latest TWO
Latest NHC Tropical Weather Discussion


"IMHO Tropical Summary"
- All the factors are beginning to shape up for something to develop soon: warmer eAtl sst's, low shear, less dry air and dust to prohibit organized t'storm activity. With the Itcz moving further north, there should be more activity; and, it should supply more moisture for waves to develop and make it easier for storms to produce the coriolis effect.

If you look at the graphic below, you'll see that a number of storms develop this time of year in the area just east of the southern islands. That's where the last few invests (except for 98) have tried to get their acts together and I think that's where we'll also see 90L develop from. There is also a chance that we could see something develop in the Caribbean and the GOM itself, depending on ridging highs and fronts that drop down.


The chance (percentage) of a named tropical cyclone in August

Tropical Cyclone Probabilities - Named Storm in August
This is the chance at any particular location that a tropical storm or hurricane will affect the area sometime during August. Based on years 1944 to 1999 in the analysis and counted hits when a storm or hurricane was within about 100 miles (165 km). (Figure by Todd Kimberlain.)


Lastly, we've already had three named storms and have closely followed two invests recently. As each wave approaches, the odds are that at least "one" will develop soon and become the first hurricane of the season. The thing that concerns me most is the position of the Bermuda/Azores high that just dominates the Atlantic.

That factor complimented by other highs extending the ridge westward with less troughs creating weaknesses, steering currents, high SST's/TCHP in the Caribbean and GOM, low shear and just general odds, points to the possibility of a serious storm developing and finding its way towards CA or the GOM.

Conditions can change, but for the time being they seem to be pointing to an intense season. If not in frequency, at least in potential intensity. The forecast for the next few days is forecast to be relatively quiet. Fortunately, that gives us more time for awareness and planning. Hopefully, we'll be better prepared in the event something does come our way!

The tropics are definitely heating up! We may get lucky, but the odds don't lend favor. The "Dean" of storms may just be in the next patch of wind!!!

"Hold down the fort and keep the gates closed!"


MLCgoodnight4.gif

Your comments and suggestions are welcome. Thanks in advance!
Have a good one!

MLC


PS: Don't forget to check out Tropical Lagniappe for some great links to other blogs and websites from fellow WU members! There's some great info here and I always learn something each time I visit them!


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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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"There is no heavier burden than a great potential." - Charles Schultz, in the Peanut's character of Linus.