Not a trace of Don; What's next?
Don is dead
Tropical Storm Don, the fourth named storm of the 2011 season, made landfall near Baffin Bay, Texas yesterday evening around 10pm CDT in less-than-grand fashion. The storm was looking very weak for the 24 hours before landfall, but fizzled rapidly after landfall, and by early Saturday morning, there was barely a trace of the storm to show that it even existed in the first place.
NHC Hurricane Specialist Eric Blake probably said it best in this mornings 5am EDT discussion on the storm:
THE DON IS DEAD. THE CYCLONE LITERALLY EVAPORATED OVER TEXAS ABOUT
AS FAST AS I HAVE EVER SEEN WITHOUT MOUNTAINS INVOLVED. DON HAS NO
CONVECTION...MEAGER RAINFALL...AND ONLY A SLIGHT SIGNATURE IN
SURFACE OBSERVATIONS AND RADAR DATA. THEREFORE...THIS IS THE LAST
ADVISORY ON THIS SYSTEM.
Figure 1. Total precipitation accumulation for the storm, estimated by radar.
The heaviest rainfall was falling south of the storm's center yesterday, so it wasn't surprising that Brownsville saw the most rain, 0.63 inches. KBRO also recorded 18 mph wind gusts. But to the north of the center, where many of the media were located, not a drop of rain fell. Corpus Christi saw zero inches of rain, but did record gale-force wind gusts (39 mph). Harlingen, near Baffin Bay, and close to where the center made landfall, saw 0.20 inches of rain and 18 mph wind gusts. This storm did very, very little to relieve any drought conditions in Southern Texas. And so it continues.
What's next: Invest 91L continues to impress
Invest 91L, which is located near 12°N 48°W in the central Atlantic, continues to impress today, and has shown signs of more organization over the past 24 hours. 91L will probably develop into a tropical cyclone before it reaches the Lesser Antilles, so residents of these islands should remain watchful and prepared. Satellite loops show not only organized thunderstorm activity, but also the makings of a surface circulation. Something this wave has working against it right now is dry air—there's a large mass of Saharan air on the north and east sides of the system, which could at least prevent significant intensification. Also, University of Wisconsin CIMSS analysis shows some strong wind shear (30-40 knots) to the north of the wave. However, I don't expect this to prevent development of the wave. Wind shear out ahead of the system is relatively low (5-15 knots). Moisture is plenty high within the system, and sea surface temperatures are warm and toasty (28°C+) and will only get warmer as 91L moves west into the Caribbean.
Figure 2. Infrared satellite of invest 91L taken at 1:15pm EDT today.
Forecast for 91L
Most of the reliable forecast models (GFS, CMC, FIM, and the ECMWF) have come to agree that 91L will develop, however, they differ on how long-lived that will be. Some of the models are suggesting it will be a short-lived tropical cyclone, not making it out of the Caribbean alive, and some suggest that it will hold together and intensify as it moves north of the Caribbean islands. The forecast track for the system will most likely be to the northwest through the Caribbean, at which point it will take a northeast turn near the Bahamas, never reaching the U.S. coast. HWRF agrees with this track (and also brings the system to category 2 strength by August 3rd). However, there is still some uncertainty that the system could track west, south of the Caribbean islands, and potentially into the Gulf of Mexico. However, none of the models that suggest this solution actually show that the wave will be a tropical cyclone at that point.
The National Hurricane Center is giving this wave an 80% chance of developing into at least Tropical Depression Five over the next 48 hours. Chances are we will see Emily out of this system. A Hurricane Hunter mission is scheduled for tomorrow at 2pm EDT, but I wouldn't be totally surprised to see them call this system this evening, given the threat to the Lesser Antilles.
Watching a northwest Caribbean disturbance
A broad area of disturbed weather is producing some heavy thunderstorms in the northwest Caribbean, southeast of the Yucatan Peninsula. Little to no low-level circulation exists with this feature, and none of the models are picking up on it. The Hurricane Center has "blobbed" this item (as I like to say) with a "near 0%" chance of developing over the next 48 hours. This disturbance could cause major flooding in the region given the amount of thunderstorm activity, and predictability for systems like this (potential Bay of Cempeche tropical cyclones) is very low. Models have a short lead time on development, and they spin up very fast once they enter the Bay of Campeche given the favorable topography of the land surrounding it. The difference between this system, though, and one like Arlene, is that there is very, very little low level circulation already present. Pre-Arlene was a bit more organized before it crossed the Yucatan, and so it's hard to imagine that this disturbance will be able to hold together, should it get that far.
If 91L develops, I'll be back tomorrow with a post.
Angela
Reader Comments
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Thanks, Angela. As usual.
The Dvorak Technique Explained
The Dvorak technique is a method using enhanced Infrared and/or visible satellite imagery to quantitatively estimate the intensity of a tropical system. Cloud patterns in satellite imagery normally show an indication of cyclogenesis before the storm reaches tropical storm intensity.
Indications of continued development and/or weakening can also be found in the cloud features. Using these features, the pattern formed by the clouds of a tropical cyclone, expected systematic development, and a series of rules, an intensity analysis and forecast can be made. This information is then standardized into an intensity code.
Full Satellite Intensity Estimate Code:
EXAMPLE: Ttt/cc/Lvv/xxhrs
Where:
T - Tropical (ST is used for Sub-Tropical systems)
tt - Satellite Derived T-Number
cc - System Current Intensity T-Number
L - Past Change
D - Developing
W - Weakening
S - Little or No change (Same)
vv - Amount of Past change in T-Number
xx - Hours over which the change was observed
EXAMPLE: T3.5/3.5/D1.0/24hrs
Translation: The system appears on satellite imagery to be T-Number 3.5 storm. This value matches the Current intensity generating about 55 knots of sustained winds. The storm has developed a full T-Number in the past 24 hours increasing the wind speeds from 35 to 55 knots. The atmospheric pressure in the center of the storm has also lowered.
EXAMPLE: T4.5/5.5/W1.0/24hrs
Translation: The system appears on satellite imagery to be T-Number 4.5 storm. The Current intensity is still 5.5 and the system is still generating sustained winds of about 100 knots. As a forecast tool, the Dvorak technique is showing a weakening trend and the likelihood of a lowering CI within the next 24hours.
Our coordination call information only contains the satellite Derived T-Number and the Current intensity (Ttt/cc).
um really now...91L is so much better organized than Don ever was....guess they have there own way of doing things..dont make no sence to me...
well if it doesnt recurve it defenitly wont hit New England and even if it curved out, the trough wont be amplified where the storm rides up the east coast. more of a wnw then nw then north then east north east.
'A 6.4 magnitude earthquake has been felt in north-east Japan, shaking buildings in the capital Tokyo, reports say.
The quake's epicentre was off the east coast of Honshu.
It struck in the same area as the 11 March earthquake and tsunami but no abnormalities at Japanese nuclear plants were reported, Reuters reports.'
Still feeling the shakes from earlier in the year, the Earth takes a while to settle properly again.
I guess it takes a very special set up to send a cyclone up here lol.
2038. stormpetrol 7:45 PM GMT on July 30, 2011 +0
91L has commenced an almost due west movement at 270-275 degrees with a well defined center near 12.5N/48.7W, jmo.
Action: Quote | Modify Comment
Like Don "POOF"
Waiting for it to form is tiring. XD
The way it looks, seems like 91L will be declared a TStorm, bypassing the Tropical depresion status...
91L looking rounder.
Quoting tropicfreak:
wow
I would say if anything, people think your a troll more than Jason by the fact that your comments are automatically minimized and his aren't. Be nice! Plenty of room for all of us here to put in our 2 cents worth on the weather
I apologize, but it just gets annoying when he keeps making several handles, which is unnecessary, sorry, I just lost my temper.
Need popcorn.
Ya estoy listo para lo que sea, no hay tanto que preparar. XD
actually that would pull future emily wnw if its closer to the ULL than the trough it will not head out to sea
Depending on how much it re-curves, Maine/Mas are probable US landfalls. If not, then on to Canada.
Actually, it's more like waiting for it to be designated, it's probably already a TD IMO.
With an ULL east of Florida, if the storm were to be in a position to the southeast of it, then the ULL while retrograded to the west, would pull the storm in tandem with it.
Indeed, it has the makings of a hurricane.
I live in western Mass, depending on how fast it moves and how directly it comes to my area, I can get the full hurricane or TS winds.
30/1745 UTC 10.4N 97.2W T1.5/1.5 96E -- East Pacific
Nice update, Angela... we are certainly keeping our eye on 91L....
don was small and lopsided due to shear. 91L is large, and cyclonic embededed with deep moisture. look whats coming off africa, another big one
The reason being is Low pressures spin counterclockwise, so a hurricane passing closely to its east would pull it more on a westerly course.
Typo on my part - it's to the West moving over FL (the ULL not big E)
Link
Also, anyone watching Typhoon Muifa? Pretty impressive Cat 4 Typhoon.
Ok; i read it twice still ant sure how they form the T numbers by just looking at the cloud pattern must be an art to this more then an guess? an enducated guess that is.
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