Not a trace of Don; What's next?

By: Dr. Jeff Masters , 19:41 GMT le 30 juillet 2011

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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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6949. luigi18
Quoting 7544:
islands are going to get a delayed last min watch hope they read the blog lol

you mean Puerto Rico
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I dont think this will hit US mainland. It will curve out to sea and become a "fish".
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It is 66 degrees here in northern Cali and it was so foggy last night it looked as though it rained this morning. Wth?
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6945. Hhunter
From Joe Bastardi,,,,,,



A picture is worth a thousand words ( it will reduce my words, which is good for you)







Under number one is the mid level circulation which has nothing bot strong southeast winds under it. A tropical wave is still in front of this with an elongated low pressure from 13 north and 61 west to near 14.5 north and 58 west. Obviously you can not direct inflow into a center with a tropical wave, a mid level center and a low level elongated low all competing with each other.



So why am I bullish on this?



Because I have seen this many times, in the southwest Pacific. Large "envelopes" of low pressure have competing convergence centers within the low and finally one will take over, and the system will pull in and deepen quickly. The GFS is now WEST OF MY PATH! Amazing since it started so far east, but it may be trying to find a center in between all this. In addition , the Cleo option, which I put on the table this morning, remains something to be considered. Cleo exploded in the central Caribbean, struck Hispaniola, hit Cuba then hit Florida. She was a fist of fury when she hit Hispaniola , got torn up, but redeveloped quickly before Cuba and still had enough punch to deliver wind gusts to 120 to Miami. The point is that its not shear that is causing the delay, but the fact this is a system that has plenty of energy to draw from, but within that system there are competing factors that are working to limit what this can do. For the sake of FLA and the SE US, as well as the islands in the way, the more that happens, the better off everyone is. But this is also the kind of system that if it gets it all together, and it should as it slows the next couple of days, it can quickly feedback

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6944. jonelu
Quoting KEEPEROFTHEGATE:



as long as it does exactly that and the shoots out to sea...Im fine with this track. We could use the rain.
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pretend its1935. deep in the depression. anyways your working on flaglers railroad. everyone is talking about a tropical storm coming but your making $$$. in a blinding rainstorms all of a sudden everyone decides to get out of there i believe the train was late too. so the last hope you jump on the train then the poop hits the fan. eye wall comes crashing through 200mph gusts waves of water running through and just hanging on the train. scary. they might consider evacuating the keys if this gets bad
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NEW BLOG!
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Aww Shucks, I was really hoping for this blog entry to get to 7000 comments before a new one was written :/
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@lucreto yea maybe its just easier for me to remember the ones that get worse and forget the ones that don't. Just think of me as someone that's gone emeritus. The only time I really get into trying to forecast these things is when they may effect my family in FL.
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But Lucreto said LSM was Laplacian Synoptic Model. From what I've been able to glean from google, Laplacian is a theory of probabilities, based on occurrences. ie: something has happened, x number of times, which gives it the probability of happening again.

Clearly not very helpful in forecasting the weather, except in the broadest terms.



Quoting AussieStorm:

Pst, LSM is a real model.
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I wonder what the odds were that 91L wouldn't develop by this point and perhaps not for a few more days at this rate? If that? Hope Rule and steering currents maps, right now anyway, take it on a sightseeing and hiking tour over Hispaniola and Cuba.

An interesting season already.
Member Since: 23 août 2008 Posts: 7 Comments: 5300
6936. beell
Quoting P451:
Look at the intense shear near the lower lesser Antilles.







Also this is a good opportunity to illustrate something I have been paying attention to in regards to the CIMSS maps we all like to utilize - and unfortunately trust too much.

Watch the imagery - all of it - all corners of it - and then keep comparing what you see on imagery to what CIMSS shows.



Doesn't quite match does it? That's because CIMSS has become very unreliable. Perhaps they always were and it just took me this long to realize it.

The lower sheared islands is under 30+kts shear easy - CIMSS diagnoses 10-15.

The mid-level/upper level circulation over 91L is diagnosed with 30-40+ kts of shear. Probably more like 15kts.

When looking to analyze systems based off of the CIMSS maps - be it shear, steering, vort maps - you have to first validate those maps as being correct before you factor them into your analysis of a system. If you pay special attention to this - in detail - you will come to notice just how unreliable these maps are.

Doing this will save you the headaches of "But Don has 5kts shear why is it's convection displaced 100s of miles south?" and "But the vort looks tremendous why isn't it spinning?" and so on and so forth.

The answer is simple: The maps are unreliable. Sometimes they line up but more often than not I have found they don't. Sometimes they are so far out of whack they are entirely useless.

While tracking Don it was easy to expose the CIMSS shear product as being absolutely useless. Their vort maps were also exposed when he was a deactivated 90L south of Cuba as being far displaced from where the actual vort was.

There are more instances but you get the picture.



Not gonna defend the CIMSS product but at some point you have to consider shear produced by the storm circulation. A system poking along embedded in easterly flow at 10 knots combined with an upper level wind with a healthy component of westerly flow at 20 knots would in fact yield 30 knots of 200mb-850mb shear on the NW quadrant of the mid level circulation. Shearing the northern half.

Some part of the system will always be under strong shear as long as upper level winds are 20-30 knots.

To put it simply-some part of the low-mid level circulation will always be in opposition to these upper level winds.

Member Since: Posts: Comments:
Quoting angiest:


Sure... blame it on the storage. I guess they already tried blaming the network.

(I am a storage admin.)
Well, let's hope they have a hot spare so there doesn't have to be an all day rebuild.

;-)
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new blog
Member Since: 25 octobre 2005 Posts: 19 Comments: 22687
Quoting CorneliaMarie:
Bowling Garden Gnome, how goes the weather in your area?


LOL Bowling?

otherwise - hot, humid, icky ....... August
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114 Hrs. Uh oh..
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NEW BLOG ENTRY
Member Since: 8 novembre 2009 Posts: 4 Comments: 13744
many models take this system over Hispaniola, through the Bahamas, off the east coast of Florida and then at some point out to sea. The near term question is, if this happens, does it survive Hispaniola?
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6928. angiest
Quoting atmoaggie:
*Some* data issues.

Lacking FNMOC windsat data in GFS:


Though WindSat data appears current as of 10:37 UTC:

(Click for full size)


Email says:
427
NOUS72 KNCF 011509
ADMNCF
THE GATEWAY IS CONTINUING TO TROUBLESHOOT THE INTERRUPTION IN THEIR DATA FEED TO
THE NCF. THEY HAVE ISOLATED THE ISSUE TO A STORAGE AREA NETWORK (SAN) DEVICE.
.
THEY HOPE TO HAVE THE ISSUE RESOLVED IN A TIMELY FASHION.
.
THANK YOU FOR YOUR PATIENCE.
.
NCF/SMS

Atmo: KNCF is the AWIPS Network Control Facility (NCF) in Silver Spring, MD, NOAA HQ.


Sure... blame it on the storage. I guess they already tried blaming the network.

(I am a storage admin.)
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6926. jpsb
Quoting P451:
Kinda hard to argue with your analyst, tstorms are collapsing as fast as they are forming too. 91L is not going to have a good day today.
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Wouldn't it be more responsible to go ahead and issue at least some tropical storm watches for the lesser antilles? If this "invest" still has winds at spots at tropical storm force, wouldn't it be better to give watches for a tropical storm regardless of weather it has a closed circulation or not?
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Jim Cantore
At this point I wouldn't be surprised to see 91L make it through the islands as an unnamed entity.
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Hispaniola takes it toll on the storm, but conditions looks favorable to get it's act back together in the bahamas.
96Hrs


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*Some* data issues.

Lacking FNMOC windsat data in GFS:

(Click for full size)


Though WindSat data appears current as of 10:37 UTC:

(Click for full size)


Email says:
427
NOUS72 KNCF 011509
ADMNCF
THE GATEWAY IS CONTINUING TO TROUBLESHOOT THE INTERRUPTION IN THEIR DATA FEED TO
THE NCF. THEY HAVE ISOLATED THE ISSUE TO A STORAGE AREA NETWORK (SAN) DEVICE.
.
THEY HOPE TO HAVE THE ISSUE RESOLVED IN A TIMELY FASHION.
.
THANK YOU FOR YOUR PATIENCE.
.
NCF/SMS

Atmo: KNCF is the AWIPS Network Control Facility (NCF) in Silver Spring, MD, NOAA HQ.
Member Since: Posts: Comments:
6918. angiest
Quoting nrtiwlnvragn:


Basically, but in this case the following fields have the radius of that wind at 0.


Thanks.
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Quoting angiest:


Ahh, so it says that is where the strongest winds are found?


Basically, but in this case the following fields have the radius of that wind at 0.
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Quoting FLdewey:
Yeah the roids will do that CanesfanatUT.

Why don't you take a swim, buy a shirt with no holes, find a beautiful wahine and take her to dinner.

Heh.

Still waiting for some exciting recon for this cloud. C'mon 91L we're paying customers here.


Never taken real gear, brah.
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6913. angiest
Quoting DestinJeff:


Probably end up going straight west, after all.


At 90 hours, still a weak system.
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6912. Gearsts
Quoting wpb:
waiting on levi post
He will come back later i think.work:/
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72 Hrs, a lot of interaction with Hispaniola.


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Quoting DestinJeff:
GFS holding south, looks like. Maybe bend north coming in future frames.


Yea it's definitely going to start pulling up NW soon, but let's see how much. Should be another interesting run.
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6906. 7544
islands are going to get a delayed last min watch hope they read the blog lol
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Wonder if the blob coming off the Florida big bend coast will become anything?
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6902. angiest
Quoting DestinJeff:
GFS holding south, looks like. Maybe bend north coming in future frames.


It's GFS, a magical trough will form in time to save the day/ ;)
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Quoting wpb:
waiting on levi post


He did an update this morning on his blog already.
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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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