Dr. Jeff Masters' WunderBlog

Not a trace of Don; What's next?
Posted by: Dr. Jeff Masters, 19:41 GMT le 30 juillet 2011 +33
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
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851. stormpetrol 00:49 GMT le 31 juillet 2011    
Quoting stormwatcherCI:
It's pouring in Grand Cayman now. Nothing is expected to develop from the wave in the western Caribbean but at least we are getting rain.

Just checking in briefly but almost all weather stations active on the Island as I posted earlier suggest some sort of circulation close to us!
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852. Patrap 00:49 GMT le 31 juillet 2011    
Im mo a Jim Beam man than a Wrestler doing weather guy
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853. Tazmanian 00:49 GMT le 31 juillet 2011    
Quoting TropicalAnalystwx13:


It says 2010...But it is the 2011 invest. Hmmm...ATCF mess-up.



they wanted too go back in time lol
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854. Gearsts 00:50 GMT le 31 juillet 2011    
Quoting Tazmanian:
bran new info in for 91L

AL, 91, 2011073100, , BEST, 0, 128N, 498W, 30, 1008, LO
Weaker? lol
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855. ryang 00:50 GMT le 31 juillet 2011    
Quoting KoritheMan:


To be fair, it's been around four years. It is not unreasonable to assume he has changed since then, right? Just a wee bit?


*thumbs up*
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856. Tazmanian 00:51 GMT le 31 juillet 2011    
Quoting Gearsts:
Weaker? lol



still the same 30kt 1008mb
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857. stormwatcherCI 00:51 GMT le 31 juillet 2011    
Quoting Levi32:
Very interesting....I think 91L's tropical wave is running away from it, based on visible satellite imagery before sunset. The main low-level vortex being called the center by ACTF is to the east, coupled (or nearly so) with the mid-level circulation. A 2nd vortex is off to the WSW, attached to the southern end of the tropical wave. The two features are becoming dissociated, with the tropical wave racing off to the west faster than the circulation which is being left behind. The secondary vortex attached to the wave is getting dragged along for the ride. The reason for this forward speed difference may lie in the fact that the surface winds (indicated by blue arrows) are much faster to the north, and since the tropical wave extended much farther north than the center of circulation, it has been pushed out ahead of it. This meridional trade wind gradient illustrates the strong cyclonic vorticity in the area, but the tropical wave decoupling from 91L's main low center may stall development, as the whole system is now more of a mess.

Which would result in further west movement, correct ?
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858. hunkerdown 00:52 GMT le 31 juillet 2011    
Quoting Levi32:
Very interesting....I think 91L's tropical wave is running away from it, based on visible satellite imagery before sunset. The main low-level vortex being called the center by ACTF is to the east, coupled (or nearly so) with the mid-level circulation. A 2nd vortex is off to the WSW, attached to the southern end of the tropical wave. The two features are becoming dissociated, with the tropical wave racing off to the west faster than the circulation which is being left behind. The secondary vortex attached to the wave is getting dragged along for the ride. The reason for this forward speed difference may lie in the fact that the surface winds (indicated by blue arrows) are much faster to the north, and since the tropical wave extended much farther north than the center of circulation, it has been pushed out ahead of it. This meridional trade wind gradient illustrates the strong cyclonic vorticity in the area, but the tropical wave decoupling from 91L's main low center may stall development, as the whole system is now more of a mess.

yet the NHC bumped up to 90% and saying could form later tonight or Sunday, hmmmm.....
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859. stormwatcherCI 00:52 GMT le 31 juillet 2011    
Quoting stormpetrol:
Quoting stormwatcherCI:
It's pouring in Grand Cayman now. Nothing is expected to develop from the wave in the western Caribbean but at least we are getting rain.

Just checking in briefly but almost all weather stations active on the Island as I posted earlier suggest some sort of circulation close to us!
IDK but it sure is some active weather in our area. Had some heavy wind gusts earlier today too.
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860. washingtonian115 00:53 GMT le 31 juillet 2011    
Quoting KoritheMan:


Yeah, that's why I said it was still up in the air. While the models have come in with a stronger trough today, that doesn't mean they will in subsequent runs.
The way the high has been this year wouldn't surprise me if the system doesn't fully recurve out into the open.
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862. Levi32 00:53 GMT le 31 juillet 2011    
Quoting stormwatcherCI:
Which would result in further west movement, correct ?


If the system actually takes longer to develop, then possibly.
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863. Patrap 00:53 GMT le 31 juillet 2011    
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864. Levi32 00:53 GMT le 31 juillet 2011    
Back later.
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865. stormwatcherCI 00:54 GMT le 31 juillet 2011    
Quoting Levi32:


If the system actually takes longer to develop, then possibly.
Any chance it takes a path like Don ?
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866. JRRP 00:55 GMT le 31 juillet 2011    

more west
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867. TropicalAnalystwx13 00:55 GMT le 31 juillet 2011    
It's pretty much a lose-lose situation at this point...for now.

If 91L decides to strengthen, it means a bigger problem to the NE islands, but then the system may curve out to sea and not affect the USA.

But if 91L stays weak, it means a lesser problem to the NE, but then the system may make landfall on the United States.

It's too early to tell which will happen.
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868. sunlinepr 00:55 GMT le 31 juillet 2011    
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869. HadesGodWyvern 00:55 GMT le 31 juillet 2011    
Japan Meteorological Agency
Tropical Cyclone Advisory #41
TYPHOON MUIFA (T1109)
9:00 AM JST July 31 2011
==========================================

SUBJECT: Category Four Typhoon In Sea East Of The Philippines

At 0:00 AM UTC, Typhoon Muifa (930 hPa) located at 16.8N 132.4E has 10 minute sustained winds of 95 knots with gusts of 135 knots. The cyclone is reported as moving north northwest slowly

Dvorak Intensity: T6.0

Storm Force Winds
=================
90 NM from the center

Gale Force Winds
=================
300 NM from the center in south quadrant
200 NM from the center in north quadrant

Forecast and Intensity
========================
24 HRS: 18.8N 132.4E - 100 knots (CAT 4/Very Strong Typhoon)
48 HRS: 21.2N 132.0E - 100 knots (CAT 4/Very Strong Typhoon)
72 HRS: 23.4N 129.7E - 95 knots (CAT 4/Very Strong Typhoon)
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870. Tazmanian 00:55 GMT le 31 juillet 2011    
Quoting TropicalAnalystwx13:


It says 2010...But it is the 2011 invest. Hmmm...ATCF mess-up.



here the update for 96E

EP, 96, 2011073100, , BEST, 0, 104N, 985W, 30, 1006, LO,
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871. Tazmanian 00:56 GMT le 31 juillet 2011    
Quoting JRRP:

more west



YAY oh did i say that lol ooops
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872. beell 00:57 GMT le 31 juillet 2011    
Quoting Levi32:
Very interesting....I think 91L's tropical wave is running away from it, based on visible satellite imagery before sunset. The main low-level vortex being called the center by ACTF is to the east, coupled (or nearly so) with the mid-level circulation. A 2nd vortex is off to the WSW, attached to the southern end of the tropical wave. The two features are becoming dissociated, with the tropical wave racing off to the west faster than the circulation which is being left behind. The secondary vortex attached to the wave is getting dragged along for the ride. The reason for this forward speed difference may lie in the fact that the surface winds (indicated by blue arrows) are much faster to the north, and since the tropical wave extended much farther north than the center of circulation, it has been pushed out ahead of it. This meridional trade wind gradient illustrates the strong cyclonic vorticity in the area, but the tropical wave decoupling from 91L's main low center may stall development, as the whole system is now more of a mess.



Fairly common for a tropical wave to tilt eastward with height.
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874. FrankZapper 00:58 GMT le 31 juillet 2011    
Quoting KoritheMan:


Yeah, the synoptic pattern is still up in the air, but the models have been coming in stronger with that trough today, which may increase the likelihood of recurvature. Still too early in the game, though. One thing I am relatively certain of is that we will not see the abundance of recurvatures this year that we saw last year.
If the persistent high can hang in just long enough and then some good longwave troughs usher in an early Fall like we used to get back in the 70s, then this hurricane season might become a season of recurves. Only what do we do with the West Carib systems to make everyone happy? .......... I know, we POOF them.
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875. mcluvincane 00:58 GMT le 31 juillet 2011    
Quoting JRRP:

more west


Look what state sticks out in its path.. NC has not had a real cane in quite some time now.
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876. KoritheMan 00:59 GMT le 31 juillet 2011    
Quoting FrankZapper:
If the persistent high can hang in just long enough and then some good longwave troughs usher in an early Fall like we used to get back in the 70s, then this hurricane season might become a season of recurves. Only what do we do with the West Carib systems to make everyone happy? .......... I know, we POOF them.


We cloud seed them, of course. ;)
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877. hotrods 01:00 GMT le 31 juillet 2011    
Models showing more west but then again take it north.
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878. HuracanTaino 01:00 GMT le 31 juillet 2011    
Quoting pottery:

A good choice of term. Very classy, as you say.
A possible 5th named system before August 1st?
I can see why we are still undecided....

heheheh
The best term for you people in the U.S, to classify storms that wont hit you, is "Non-U.S.storms," simple. But to call a 'fish storm" a system that had affected or could affect, in one way or another thousands of people, is offensive. Don't you think?
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879. Torgen 01:00 GMT le 31 juillet 2011    
Quoting CosmicEvents:
Greetings Pottery.
We haven't decided on the season being a bust or not as yet, but the term "fish storms" is out. We've moved on to "mal vent pour la poisson" so as to not upset anyone. It sounds classier as well.
.
.


Can I get that with white sauce and steamed asparagus?
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880. weathermanwannabe 01:00 GMT le 31 juillet 2011    
Off to bed (early am fishing trip)...See Yall tomorrow afternoon............WW
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881. KoritheMan 01:00 GMT le 31 juillet 2011    
Quoting beell:


Fairly common for a tropical wave to tilt eastward with height.


Correct.
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883. Walshy 01:02 GMT le 31 juillet 2011    
Quoting mcluvincane:


Look what state sticks out in its path.. NC has not had a real cane in quite some time now.


Last I remember was Hurricane Isabel.
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884. markot 01:03 GMT le 31 juillet 2011    
cmc is going more west, as is gfdl...
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885. stormwatcherCI 01:04 GMT le 31 juillet 2011    
Quoting KoritheMan:


Correct.
Kori, any chance 91L follows Don's path ?
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886. Patrap 01:04 GMT le 31 juillet 2011    
Muifa


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887. washingtonian115 01:05 GMT le 31 juillet 2011    
Quoting markot:
cmc is going more west, as is gfdl...
Have not seen you in like 10,000 years.Where ya been?
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888. hotrods 01:05 GMT le 31 juillet 2011    
Im not understanding the nogaps model at this point, earlier 18z showed up the east coast of Florida and now the swfmd-18 shows bahamas, can someone explain?
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889. TropicalAnalystwx13 01:05 GMT le 31 juillet 2011    
Quoting Walshy:


Last I remember was Hurricane Isabel.


No, our last one was Hurricane Ophelia in 2005.
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890. FrankZapper 01:06 GMT le 31 juillet 2011    
Outstanding observation, Levi!
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891. KoritheMan 01:06 GMT le 31 juillet 2011    
Quoting stormwatcherCI:
Kori, any chance 91L follows Don's path ?


I don't think so unless development is significantly impeded.
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892. stormwatcherCI 01:06 GMT le 31 juillet 2011    
Quoting KoritheMan:


I don't think so unless development is significantly impeded.
But there is a chance still right ?
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893. floridaboy14 01:08 GMT le 31 juillet 2011    
if the tropical wave outruns the low pressure what that simply means is that the low pressure to the east will start to consildate more as the old low pressure with the wave dissipates.
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894. ackee 01:10 GMT le 31 juillet 2011    
Quoting JRRP:

more west
I think models will shift further west with each run
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895. FrankZapper 01:10 GMT le 31 juillet 2011    
Quoting HuracanTaino:
The best term for you people in the U.S, to classify storms that wont hit you, is "Non-U.S.storms," simple. But to call a 'fish storm" a system that had affected or could affect, in one way or another thousands of people, is offensive. Don't you think?
When we say fish we mean the eye does not cross ANY land, period.
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897. JRRP 01:11 GMT le 31 juillet 2011    
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898. washingtonian115 01:11 GMT le 31 juillet 2011    
Quoting stormwatcherCI:
But there is a chance still right ?
Unless it stays really weak,and can continue on a southerly route like some of the models are showing.But I don't really see it happening.
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899. stormhank 01:11 GMT le 31 juillet 2011    
Ive read from several sources this season may not have many recurves as last year due to the neutral ENSO phase?? Anyone feel that this season could resemble 2008?? thanks for any input??
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900. washingtonian115 01:12 GMT le 31 juillet 2011    
Quoting ackee:
I think models will shift further west with each run
Yeah...Just like with Earl.....
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901. Patrap 01:13 GMT le 31 juillet 2011    
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About JeffMasters
Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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