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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4902. aspectre 01:44 GMT le 01 août 2011    
12.4n47.9w, 12.7n49.1w, 12.9n50.3w, 13.2n51.5w, 13.5n52.8w have been re-evaluated&altered by the NHC for the 12amGMT ATCF
12.5n48.6w, 12.7n50.0w, 12.9n51.5w, 13.0n53.1w, 13.2n54.9w, 13.3n56.5w are now the most recent positions


Copy&paste 12.5n48.6w, 12.7n50.0w-12.9n51.5w, 12.9n51.5w-13.0n53.1w, 13.0n53.1w-13.2n54.9w, 13.2n54.9w-13.3n56.5w, bqn, uvf, 13.2n54.9w-13.52n60.95w into the GreatCircleMapper for more info

Using straightline projection of the travel-speed&heading derived from the ATCF coordinates for 6pmGMT then 12mGMT :
91L was headed toward passage into the Caribbean with a travel-speed of 18mph(29k/h);
narrowly going north of Barbados ~10hours30minutes from now,
then narrowly going south of St.Lucia in ~15hours from now.
Member Since: 21 août 2007 Posts: 0 Comments: 4846
4903. Slamguitar 01:44 GMT le 01 août 2011    
Quoting DirtDan:
Don't look now but it looks like this system is getting the piss sheared out of it.... I said it 36 hours ago, but all of the talking heads on this blog said I didn't know what I was talking about..... LOL Can we see Emily in the next 36 hours...????? I say NOT..... Shear and dry air to the north is killing this thing..... Moisture will get better in the next 36 to 48 hours, but I still think that that Hispanola will give it a mega negative impact before it gets better..............


I have a feeling 91L will be a fighter just like Don. She just needs to shed some of that excess weight. ;)
Member Since: 2 juillet 2011 Posts: 0 Comments: 1021
4904. Mikla 01:44 GMT le 01 août 2011    
I think the NHC is on the fence and is still balancing due to the lack of HH data. The Dropsonde data appears to be inconclusive but did have some decent wind readings. RGB appeared to have closed circulation earlier, but it is hard to tell now. SAL dry air is still getting in at the mid-levels (see Dropsonde data) and shear (10-20kts) is still affecting the structure. Convection has also been a bit disorganized, but there has been plenty of it. The oddity is the wave out in front of the apparent center that is firing a good deal of its own convection and appears to be affecting the organization of the thunderstorms behind it. Also, there is good model support for development but the models have been shifting left due to the slow development (thus a shallow system that moves with steering currents). Now, throw in the fact that 91L is getting close to land, I am sure the stress is high at the NHC on what to do. Personally I think we will see a TD before the sun rises tomorrow (EST), but would not be surprised if it does not occur until later in the day tomorrow… Just IMHO…
Member Since: 13 octobre 2006 Posts: 0 Comments: 201
4905. DirtDan 01:45 GMT le 01 août 2011    
Quoting HurricaneSwirl:


I swear you've said that over and over for the last two pages. Do you think we can't read? XD



I said it yesterday at 3 PM EST..... All of the junior mets said I didn't know what I was talking about..... Don't ever discount wind shear.....
Member Since: 1 juillet 2007 Posts: 0 Comments: 63
4907. JLPR2 01:45 GMT le 01 août 2011    
Quoting CybrTeddy:
Yea, 91L is a disorganized mess right now. That's to be expected, we've had competing circulation all day, neither of them appearing to be closed and sucking the life out of one another with only marginal surface convergence. I do not think 91L will develop until tomorrow, maybe even as late as early Tuesday AM. It has a lot of work to do, but I think right now it is attempting to gain a dominate circulation. Gradual development, not rapid..


Yep, lots to do...
Member Since: 4 septembre 2007 Posts: 7 Comments: 7491
4908. GTcooliebai 01:45 GMT le 01 août 2011    

Ensembles all over the place!
Member Since: 31 août 2009 Posts: 0 Comments: 5205
4909. TropicalAnalystwx13 01:45 GMT le 01 août 2011    
Quoting jasonweatherman2011:
i think you are right the wind shear is 20 knots over invest 91L LOOK at the wind shear map!!


WOW THAT IS SO AMAZING!!!
Member Since: 6 juillet 2010 Posts: 89 Comments: 25360
4910. KEEPEROFTHEGATE (Mod) 01:46 GMT le 01 août 2011    
T.C.F.W.
91L/INV/XX
MARK CENTER OF IMAGE
14.950N/55.23W
Member Since: 15 juillet 2006 Posts: 144 Comments: 40670
4911. BahaHurican 01:46 GMT le 01 août 2011    
So it's shear that's causing the separation?
Member Since: 25 octobre 2005 Posts: 19 Comments: 17690
4912. futuremet 01:46 GMT le 01 août 2011    
Quoting BahaHurican:
I wonder what conditions we're not taking into account with these CV systems. This is the second in a row that looked great as it approached the Lesser Antilles, then fell apart due to competing circulations. Both were sufficiently shielded from dry air intrusion at the time. Both were moving along at near 20 mph. What is causing this multi-vortex situation to develop?


Multiple vortices are not atypical in fluids. There are various factors that can induce multiple vortices. In the case of a tropical cyclone, it is primarily because most of the energy gets allocated into different areas of low pressure. This can happen if there are multiple dominant areas of low pressure. These types of phenomena are especially common in broad tropical systems.


P.S. I still regularly monitor this blog, but I can no longer post. I have been too busy lately. This might be my last post of the year.
Member Since: 19 juillet 2008 Posts: 43 Comments: 4049
4913. hunkerdown 01:48 GMT le 01 août 2011    
Quoting DirtDan:



I said it yesterday at 3 PM EST..... All of the junior mets said I didn't know what I was talking about..... Don't ever discount wind shear.....
you must be dumber than DirtDan cause HurricaneSwirl's comment wasn't directed at you...
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4915. Dakster 01:48 GMT le 01 août 2011    
Can 91L just go "poof" already... Either form or dissipate, this is worse that watching the us debt debate.
Member Since: 10 Mars 2006 Posts: 0 Comments: 4942
4917. MiamiHurricanes09 01:49 GMT le 01 août 2011    
The best analogs as far as track for 91L appear to be Floyd and David. Currently I'm more inclined to say that this system will mimic something more similar to Floyd, but the fact that the system probably won't be organizing into anything too intense anytime soon, thus a more westerly track, a David-like track is slowly becoming more and more likely.
Member Since: 2 septembre 2009 Posts: 129 Comments: 19976
4919. PcolaDan 01:49 GMT le 01 août 2011    
Quoting hunkerdown:
doesn't that model have a typical skew toward the southeast ?


Conversely, the "Look Man Not Our Problem" model means we will be safe. :)
Member Since: 22 août 2008 Posts: 12 Comments: 6008
4920. hunkerdown 01:49 GMT le 01 août 2011    
Quoting lucreto:


Apparently all you need to know about tropical meteorology is "There is 20 knots of shear over it right now!!!!!!!"
WOW!!
Member Since: 15 août 2008 Posts: 0 Comments: 2514
4921. Dakster 01:50 GMT le 01 août 2011    
FUTUREMET!!!! We need you! Please stay and post.

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4922. xcool 01:51 GMT le 01 août 2011    
futuremet Please stay
Member Since: 26 septembre 2009 Posts: 2 Comments: 15503
4924. JLPR2 01:51 GMT le 01 août 2011    
Since everyone is picking a center I'll go with 14.5N, 55W ;)
Member Since: 4 septembre 2007 Posts: 7 Comments: 7491
4925. atmoaggie 01:52 GMT le 01 août 2011    
Quoting BahaHurican:
So it's shear that's causing the separation?
Or a speed divergence with the easterlies speeding up in the western part of 91L's domain.

(Not sure, but a possibility)
Member Since: 16 août 2007 Posts: 6 Comments: 12461
4926. Bretts9112 01:52 GMT le 01 août 2011    
Quoting DirtDan:



Jason.... Yer a typical yo-yo... You called shit on this system for the last 48 hours...... IS IT A FISH STORM....??????????????????????? You call paths before it's even designated a storm..... Sorry... We all have opinions, but you have pretty much become the joke of the blog..... Watch, learn and shut up already...... I'm a lurker of over a decade now and you get on my last nerve.............

Just put him on Ignore I did, I cant stand that guy.
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4928. atmoaggie 01:52 GMT le 01 août 2011    
Quoting futuremet:


Multiple vortices are not atypical in fluids. There are various factors that can induce multiple vortices. In the case of a tropical cyclone, it is primarily because most of the energy gets allocated into different areas of low pressure. This can happen if there are multiple dominant areas of low pressure. These types of phenomena are especially common in broad tropical systems.


P.S. I still regularly monitor this blog, but I can no longer post. I have been too busy lately. This might be my last post of the year.
Right on.

Howdy, BTW.
Member Since: 16 août 2007 Posts: 6 Comments: 12461
4930. louisianaweatherguy 01:53 GMT le 01 août 2011    
if trends continue, model consensus will shift to Florida/Eastern GOM tommorrow...
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4931. GTcooliebai 01:53 GMT le 01 août 2011    

Wow! David had winds of 175 mph...talk about nastiness
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4932. Thrawst 01:54 GMT le 01 août 2011    
Quoting Stormchaser2007:
Red line is the 00z consensus



O_O .. we'd be in the northeast quad of the cyclone if the consensus were to be true in that pic.
Member Since: 18 juillet 2010 Posts: 49 Comments: 1067
4933. KEEPEROFTHEGATE (Mod) 01:54 GMT le 01 août 2011    
Member Since: 15 juillet 2006 Posts: 144 Comments: 40670
4935. KEEPEROFTHEGATE (Mod) 01:54 GMT le 01 août 2011    
Member Since: 15 juillet 2006 Posts: 144 Comments: 40670
4936. HurricaneSwirl 01:54 GMT le 01 août 2011    
Quoting DirtDan:



I said it yesterday at 3 PM EST..... All of the junior mets said I didn't know what I was talking about..... Don't ever discount wind shear.....


Eh I'm not discounting anything. Just tired of reading the same statement in all caps by the same guy haha. I didn't really have any beef with what you were saying.


However, SHIPS believes wind shear will drop down to 4 knots in 12 hours (and never exceeding 15 throughout the forecast period) though. Dry air to me seems to be a bigger problem for 91L with relative humidity values supposed to hover around 50 for much of the forecast period.

And other map such as this one show low shear:


Tonight 91L's going through tough times. It's working on absorbing back what the disconnected wave brought out of it yesterday, and it's working in (now it's just past) DMIN. I think once it merges and hits DMAX I think we'll see a much better looking system.
Member Since: 7 juillet 2008 Posts: 2 Comments: 3237
4937. EYEStoSEA 01:55 GMT le 01 août 2011    
Quoting Dakster:
Can 91L just go "poof" already... Either form or dissipate, this is worse that watching the us debt debate.


I'll second that !! Ya know they say you gain patience with age....well it ain't happening for me, not with these Invest anyway :/
Member Since: 16 septembre 2010 Posts: 0 Comments: 1491
4938. BahaHurican 01:55 GMT le 01 août 2011    
Quoting futuremet:


Multiple vortices are not atypical in fluids. There are various factors that can induce multiple vortices. In the case of a tropical cyclone, it is primarily because most of the energy gets allocated into different areas of low pressure. This can happen if there are multiple dominant areas of low pressure. These types of phenomena are especially common in broad tropical systems.


P.S. I still regularly monitor this blog, but I can no longer post. I have been too busy lately. This might be my last post of the year.
Wow! Great to see u here, and a pity - a great one! - u may not be able 2 post anymore.... I hope u r busy doing all those things u need to get done to make that "future met" status a reality....
Member Since: 25 octobre 2005 Posts: 19 Comments: 17690
4939. bigeasystormcaster 01:55 GMT le 01 août 2011    
In regard to some of the members observing windshear over 91L, this was caused by the wave preceding 91L which is now diminishing. As a result thunderstorms are increasing around the presumed center of 91L as can be observed in very recent satellite imagery. This is why i have forecasted a much better organized and stronger system in the morning. This is why this system should develop to some extent and not discipate. The windshear has been a temporary problem for 91L that it is now overcoming.
Member Since: 30 juillet 2011 Posts: 0 Comments: 109
4942. MiamiHurricanes09 01:57 GMT le 01 août 2011    
4923. DirtDan 9:51 PM EDT on July 31, 2011

Check this out man, just takes one button.

Member Since: 2 septembre 2009 Posts: 129 Comments: 19976
4943. hunkerdown 01:57 GMT le 01 août 2011    
Quoting GTcooliebai:

Wow! David had winds of 175 mph...talk about nastiness
please, refrain from the use of "wow"...it is posted far to many times an hour by the "man" with many, er, too many, handlers...
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4945. atmoaggie 01:59 GMT le 01 août 2011    
Hot, fresh Guadeloupe sounding:

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4946. JLPR2 01:59 GMT le 01 août 2011    
I'll repeat this for the reapers, 91L isn't doing so horribly bad tonight. Convection is now forming in a circle over or close to the mystery circulation and as 456 said earlier today once 91L reaches the area where the TW preceding it blew up with convection, it should do that as well and presto... TD 5.
Member Since: 4 septembre 2007 Posts: 7 Comments: 7491
4947. PrivateIdaho 01:59 GMT le 01 août 2011    
Quoting FLdewey:


LOL... seemed appropriate for all of the screaming going on earlier... err still going on.

Be calm folks... it's early in the season yet.

BEHOLD:



Noooooooooooooo!!!!!!!
Member Since: 29 août 2010 Posts: 0 Comments: 5211
4948. Hurricanejer95 01:59 GMT le 01 août 2011    
Convection is starting to regenerate, more reds near the center
Link
Member Since: 30 août 2008 Posts: 1 Comments: 224
4949. MiamiHurricanes09 02:00 GMT le 01 août 2011    
Quoting hunkerdown:
please, refrain from the use of "wow"...it is posted far to many times an hour by the "man" with many, er, too many, handlers...
Just created another one to talk to himself... LOL
Member Since: 2 septembre 2009 Posts: 129 Comments: 19976
4950. HurricaneKyle 02:00 GMT le 01 août 2011    
hello i don't post much these days, but i do lurk often. I wanted to come out of lurk mode to address the calls of weakening. Right now our invest is disorganized, dealing with duel vorticies and will probably remain that way throughout the night. that's not to say it won't develop however. I have never seen a storm with this tight of model support not develop even if the models have been doing poor this year (however they all showed storms not developing, this all shows them developing)

fair warning, if this stays weak the more likely it will hit the USA.. if it stays weak enought it might even thread the oceans between Cuba and Hispaniola.
Member Since: 10 août 2009 Posts: 3 Comments: 672

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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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