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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First person to arrive at the crash site was a Taxi.
He CHARGED the people $20.00 to drop them to the terminal.......
Indeed. The parent tropical wave appears to have left 91L behind and will move across the Islands today producing heavy rainfall ahead of the main event. Not good at all .....
Nothing short of a miracle.
An inverted trough is an atmospheric trough which is oriented opposite to most troughs of the mid-latitudes. Some inverted troughs are tropical waves which can also be referred to as easterly waves.
Most of the troughs of Low Pressure are areas of decreasing atmospheric pressure (we see it when the barometer falls) are from SOUTH to NORTH while our Inverted Troughs are characterized by that decreasing pressure from NORTH to SOUTH. While normal troughs or tropical waves move from EAST to WEST, INVERTED TROUGHS move from WEST to EAST.
All Troughs can be at the surface, upper level or both depending on the conditions. Most Troughs bring clouds, showers and a change in wind directions especially after the passing of the trough which is a result of convergence which causes lifting of moist are behind the trough line.
Yeah, I read that yesterday. Free enterprise at its finest, I suppose. :-\
---
Obviously, with how fast for example, Ivan developed, we in the isalnds need to be prepared. This WILL be a strong storm or even a CAT 1 when it passes the islands.
The only question is where, which is the problem. The only answer to that question is to just be prepared., without getting panicky.
I've got supplies, but likely many will panic and rush to stores today, not pretty.
The system seems to have gone just westerly overnight, so not sure the models have caught on it properly, which may be expected until it develops.
Ah well, here we go again....
Take Care.
(Lost all my links - laptop death. Now have to wrestle with a German keyboard.)
Stange....
...no kidding.
They partially missed... not showing from what I can see a complete closed circulation yet. At least from the "angle" it was taken from:
Say it extends at most 200 miles, that gives 400 miles to full system (apart from stray clouds).
400 miles at 20 mph is 20 hours.
So the system has a full day before it actually touches an island and a day and a quarter or half before the centre gets to an island, at the earliest.
A lot can happen in a full day and night with this heat about.
Emily.
A lot of rainfall has occured in the last 3 - 5 days in the same areas being threatened so the ground is very saturated. Any more rainfall could lead to significant flooding and landslides.
can you put up a link?
Yes think Dr.Masters did note that a concern was the one the GFS (I think) agressively developed, right after 'Emily'.
The train is on quite early.
Hmm. You'd expect it fulfills the criteria by now, looks healthy. However, it is approaching 55W. If it doesn't have what it needs under the bonnet\hood, the Hope Rule could come into play.
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN JUL 31 2011
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
SATELLITE IMAGES AND NOAA BUOY DATA INDICATE THAT THE LARGE AND
ELONGATED LOW PRESSURE SYSTEM CENTERED ABOUT 650 MILES EAST OF
THE NORTHERN WINDWARD ISLANDS CONTINUES TO BECOME BETTER
ORGANIZED...AND IT COULD DEVELOP INTO A TROPICAL DEPRESSION AT ANY
TIME. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 24 TO 48 HOURS AS IT
MOVES WEST-NORTHWESTWARD NEAR 15 MPH. IF THE LOW BECOMES A TROPICAL
CYCLONE LATER TODAY...TROPICAL STORM WATCHES OR WARNINGS WOULD
LIKELY BE REQUIRED FOR PORTIONS OF THE NORTHERN WINDWARD ISLANDS
AND THE LEEWARD ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY
MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE UNIT
RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS
DISTURBANCE LATER THIS AFTERNOON.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
----------
Loooking at the satellite loop, 'Emily' is now pulling together, definitely a storm by end of day, strengthening overnoght into Monday am.
The 'only' thing could stop is without shear etc, is for the system behind to draw from it, thus weakening it, but that one seems too far back to do much to 'Emily'.
ABNT20 KNHC 311142
TWOAT
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN JUL 31 2011
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
SATELLITE IMAGES AND NOAA BUOY DATA INDICATE THAT THE LARGE AND
ELONGATED LOW PRESSURE SYSTEM CENTERED ABOUT 650 MILES EAST OF
THE NORTHERN WINDWARD ISLANDS CONTINUES TO BECOME BETTER
ORGANIZED...AND IT COULD DEVELOP INTO A TROPICAL DEPRESSION AT ANY
TIME. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 24 TO 48 HOURS AS IT
MOVES WEST-NORTHWESTWARD NEAR 15 MPH. IF THE LOW BECOMES A TROPICAL
CYCLONE LATER TODAY...TROPICAL STORM WATCHES OR WARNINGS WOULD
LIKELY BE REQUIRED FOR PORTIONS OF THE NORTHERN WINDWARD ISLANDS
AND THE LEEWARD ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY
MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE UNIT
RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS
DISTURBANCE LATER THIS AFTERNOON.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER STEWART
Later.
wouldnt this help 91L because yesterday it had 2 centers 1 asscociated with the wave and another one with th elow pressure and ive noticed since the wave seperated convection strong around 91L's center. you think it helped or weakened 91?
:) Indeed... you would. So in my opinion, I wouldn't expect for now any updates (status change wise - INVEST -> TD, etc...) on the TWO's until a HH arrives at the location today.
You don't have to bet your life (I know figure of speech of some sort... haha). Since they waited this long... then they're willing to wait a couple more hours until the HH departs:
1. SUSPECT AREA (CENTRAL ATLANTIC)
FLIGHT ONE -- TEAL 70
A. 31/1800Z
B. AFXXX 01EEA INVEST
C. 31/1530Z
D. 14.5N 56.0W
E. 31/1730Z TO 31/2330Z
F. SFC TO 10,000 FT
Should be heading out by 11:30AM ET (knock on wood).
ABNT20 KNHC 311142
TWOAT
TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN JUL 31 2011
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
SATELLITE IMAGES AND NOAA BUOY DATA INDICATE THAT THE LARGE AND
ELONGATED LOW PRESSURE SYSTEM CENTERED ABOUT 650 MILES EAST OF
THE NORTHERN WINDWARD ISLANDS CONTINUES TO BECOME BETTER
ORGANIZED...AND IT COULD DEVELOP INTO A TROPICAL DEPRESSION AT ANY
TIME. THIS SYSTEM HAS A HIGH CHANCE...NEAR 100 PERCENT...OF
BECOMING A TROPICAL CYCLONE DURING THE NEXT 24 TO 48 HOURS AS IT
MOVES WEST-NORTHWESTWARD NEAR 15 MPH. IF THE LOW BECOMES A TROPICAL
CYCLONE LATER TODAY...TROPICAL STORM WATCHES OR WARNINGS WOULD
LIKELY BE REQUIRED FOR PORTIONS OF THE NORTHERN WINDWARD ISLANDS
AND THE LEEWARD ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY
MONITOR THE PROGRESS OF THIS SYSTEM. AN AIR FORCE RESERVE UNIT
RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS
DISTURBANCE LATER THIS AFTERNOON.ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
$$
FORECASTER STEWART
Or because it isn't even 8am EDT and everybody is still in bed.
GFDL
is not impressed with 91L.
It might help to moisten the environment ahead of 91L lessening the dry air we saw yesterday and that's going to allow 91L to strenghen.
This PAGE should keep you busy for awhile!
Naaahh...we're just all drumming our fingers and going "hhmmmph."
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