Dr. Jeff Masters' WunderBlog

High wind shear ripping into 97L
Posted by: Dr. Jeff Masters, 01:49 PM GMT del 20 Luglio 2009 +2
A strong tropical wave (97L) a few hundred miles east of Barbados in the Lesser Antilles Islands has grown less organized today as it tracks west at 15 - 20 mph. The wave is moving underneath an upper-level trough of low pressure, which is bringing 30 knots of wind shear to 97L. While there is a respectable amount of heavy thunderstorm activity associated with 97L, there is no longer any low-level spiral banding or rotation of the cloud pattern. This morning's QuikSCAT pass at 5:35 am EDT showed sustained winds of 35 mph a few hundred miles east of Barbados, but there was no surface circulation evident. The islands of Barbados, St. Vincent and the Grenadines, St. Lucia, and Martinique can expect heavy rain and wind gusts to 50 mph as 97L moves through the Lesser Antilles Islands this afternoon and tonight, but 97L will not become a tropical depression.

Wind shear along the path of 97L is forecast to remain in the high 25 - 35 knot range for at least the next three days. This should prevent further development of 97L, and I expect the disturbance will be gradually torn apart during the next few days. The National Hurricane Center gives 97L a low (less than 30% chance) of developing into a tropical depression in the next 48 hours. None of the computer models are forecasting any tropical storm development over the next seven days.


Figure 1. Current satellite image of African wave 97L.

I'll have an update Tuesday morning. As 97L moves through the islands, you may want to follow local observations there using our wundermap for the region.

Jeff Masters
Categories: Hurricane
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351. stormsurge39 04:21 PM GMT del 20 Luglio 2009    
Does anybody else see that the shear maps are not matching what it looks like on the satt? Am i the only crazy one here?
352. HurricaneSwirl 04:21 PM GMT del 20 Luglio 2009    
Quoting KEEPEROFTHEGATE:
YOU SHOULD NOT BE DOING THAT AT A TIME LIKE THIS IT IS NOT RIGHT


sheeeshh. i get the point already >.>

not right? I stated before my post "this will never happen" and i stated after my post "nothing against the cayman islands" and "nothing against the nhc". but i see you posted around the same time that i did
Member Since: Luglio 7, 2008 Posts: 2 Comments: 3237
353. weatherwatcher12 04:22 PM GMT del 20 Luglio 2009    
Quoting stormsurge39:
Does anybody else see that the shear maps are not matching what it looks like on the satt? Am i the only crazy one here?

It's updating in 18 mins
Member Since: Maggio 16, 2009 Posts: 1 Comments: 1231
354. Seastep 04:22 PM GMT del 20 Luglio 2009    
341. stormsurge

New maps should be out soon. CIMSS are from over four hours ago... and it did look different then.
Member Since: Settembre 9, 2008 Posts: 6 Comments: 3406
355. Drakoen 04:22 PM GMT del 20 Luglio 2009    
Quoting weatherwatcher12:

What do you think about the westerlies in Trinidad


I have been looking south of the system and you can see low level clouds veering SW:
Member Since: Ottobre 28, 2006 Posts: 57 Comments: 29010
356. TampaSpin 04:25 PM GMT del 20 Luglio 2009    
Quoting stormsurge39:
Does anybody else see that the shear maps are not matching what it looks like on the satt? Am i the only crazy one here?


Shear is easily 30-35kts.......maybe this loop will help you!
Member Since: Settembre 2, 2007 Posts: 175 Comments: 19747
357. Drakoen 04:26 PM GMT del 20 Luglio 2009    
Member Since: Ottobre 28, 2006 Posts: 57 Comments: 29010
358. hurricanefiend85 04:29 PM GMT del 20 Luglio 2009    
How do they produce the 'future' shear maps? Are they computer models such as the computer models for when storms do form? I guess my real question is, how accurate are the models for future shear? Is there some statistical data similar to what can be found for tropical storm models?
Member Since: Febbraio 11, 2009 Posts: 0 Comments: 42
359. Drakoen 04:29 PM GMT del 20 Luglio 2009    
Member Since: Ottobre 28, 2006 Posts: 57 Comments: 29010
360. nrtiwlnvragn 04:29 PM GMT del 20 Luglio 2009    
Interesting views of 97L from Windsat. No time stamp on those images, but the scat time stamp is 0946.
Member Since: Settembre 23, 2005 Posts: 11 Comments: 8946
362. weatherwatcher12 04:30 PM GMT del 20 Luglio 2009    
Quoting nrtiwlnvragn:
Interesting views of 97L from Windsat. No time stamp on those images, but the scat time stamp is 0946.

It is very interesting
Member Since: Maggio 16, 2009 Posts: 1 Comments: 1231
363. ArmyWifeInGa 04:31 PM GMT del 20 Luglio 2009    
Who was it that showed us that wind storm on the beach in Florida yesterday? I just saw that same video on the weather channel.
364. K8eCane 04:32 PM GMT del 20 Luglio 2009    
I just noticed a blob east of the northern bahamas moving NW. Is that potentially a formation of some kind?
Member Since: Aprile 26, 2006 Posts: 5 Comments: 2375
365. BenBIogger 04:32 PM GMT del 20 Luglio 2009    
Member Since: Marzo 19, 2009 Posts: 0 Comments: 1419
366. K8eCane 04:33 PM GMT del 20 Luglio 2009    
Quoting K8eCane:
I just noticed a blob east of the northern bahamas moving NW. Is that potentially a formation of some kind?



on second thought if it was i guess the NHC would be on top of it
Member Since: Aprile 26, 2006 Posts: 5 Comments: 2375
367. jeffs713 04:35 PM GMT del 20 Luglio 2009    
Quoting K8eCane:
I just noticed a blob east of the northern bahamas moving NW. Is that potentially a formation of some kind?

No, that is tied to the stalled out front draped over FL.
Member Since: Agosto 3, 2008 Posts: 15 Comments: 5722
368. K8eCane 04:36 PM GMT del 20 Luglio 2009    
Quoting jeffs713:

No, that is tied to the stalled out front draped over FL.


ok thanks
Member Since: Aprile 26, 2006 Posts: 5 Comments: 2375
369. canesrule1 04:36 PM GMT del 20 Luglio 2009    
Quoting BenBIogger:
odd at the bottom left, maybe an LLC is forming, thoughts?
370. TampaSpin 04:37 PM GMT del 20 Luglio 2009    
Quoting btwntx08:

u put shear 30-30 lol unless u meant 20-30 kts


sorry meant 30-35
Member Since: Settembre 2, 2007 Posts: 175 Comments: 19747
371. WPBHurricane05 04:37 PM GMT del 20 Luglio 2009    
.
Member Since: Luglio 31, 2006 Posts: 56 Comments: 7929
372. weathermanwannabe 04:37 PM GMT del 20 Luglio 2009    
Stupid Basic Question Here....Everyone looks at/uses the CIMSS charts when looking at the sheer...........How is the sheer data derived for those Charts (Satt Estimates/Weather Ballons/combination of both?).....Thanks
Member Since: Agosto 8, 2006 Posts: 0 Comments: 6703
373. serialteg 04:37 PM GMT del 20 Luglio 2009    
am i the only one following the wave behind 97l? surprised the blogger didnt talk about it, been following it for a couple of days now and still holding / getting stronger plus it has like 2 days before hitting W shear (its getting hit by S but not nearly as bad)
Member Since: Agosto 22, 2006 Posts: 2 Comments: 1966
374. weatherwatcher12 04:38 PM GMT del 20 Luglio 2009    
Quoting serialteg:
am i the only one following the wave behind 97l? surprised the blogger didnt talk about it, been following it for a couple of days now and still holding / getting stronger plus it has like 2 days before hitting W shear (its getting hit by S but not nearly as bad)

I'm watching it also
Member Since: Maggio 16, 2009 Posts: 1 Comments: 1231
375. WPBHurricane05 04:39 PM GMT del 20 Luglio 2009    
Being late July, I would watc.h it

Quoting K8eCane:
I just noticed a blob east of the northern bahamas moving NW. Is that potentially a formation of some kind?
Member Since: Luglio 31, 2006 Posts: 56 Comments: 7929
376. LPStormspotter 04:39 PM GMT del 20 Luglio 2009    
Quoting STORMMASTERG:
If 97l surves it will go northwest to near cuba/than southwest to mexico or western gulf.


Mexico...
Member Since: Luglio 17, 2008 Posts: 0 Comments: 378
377. weatherwatcher12 04:40 PM GMT del 20 Luglio 2009    
New map
Member Since: Maggio 16, 2009 Posts: 1 Comments: 1231
378. futuremet 04:40 PM GMT del 20 Luglio 2009    
Shear seems to be decreasing; the streaming pattern is less pronounced.
Member Since: Luglio 19, 2008 Posts: 43 Comments: 4049
380. canesrule1 04:40 PM GMT del 20 Luglio 2009    
Quoting serialteg:
am i the only one following the wave behind 97l? surprised the blogger didnt talk about it, been following it for a couple of days now and still holding / getting stronger plus it has like 2 days before hitting W shear (its getting hit by S but not nearly as bad)
the little talk about it was that it was too low.
381. K8eCane 04:40 PM GMT del 20 Luglio 2009    
Quoting WPBHurricane05:
Being late July, I would watc.h it




ok thanks WPB
i will
it just looks foreboding to me
and before anybody bashes me i said TO ME
Member Since: Aprile 26, 2006 Posts: 5 Comments: 2375
382. Drakoen 04:41 PM GMT del 20 Luglio 2009    
The updated CIMSS shows shear at 20-30knots and a pocket of decreasing shear out ahead of the system. The 700-850mb vort maximum has increased and is vertically stacked.
Member Since: Ottobre 28, 2006 Posts: 57 Comments: 29010
384. canesrule1 04:41 PM GMT del 20 Luglio 2009    
Quoting weatherwatcher12:
New map
where 97L is going shear went down 10 knots, not bad.
385. Drakoen 04:42 PM GMT del 20 Luglio 2009    
Let's play the game:
In the next TWO 97L will have:

A)Yellow Circle
B)Orange Circle
C)Red Circle
D)No Circle
Member Since: Ottobre 28, 2006 Posts: 57 Comments: 29010
386. BurnedAfterPosting 04:42 PM GMT del 20 Luglio 2009    
Quoting Drakoen:
The updated CIMSS shows shear at 20-30knots and a pocket of decreasing shear out ahead of the system. The 700-850mb vort maximum has increased and is vertically stacked.


I think it is due to the ULL lifting out to the NW
387. BurnedAfterPosting 04:43 PM GMT del 20 Luglio 2009    
Quoting Drakoen:
Let's play the game:
In the next TWO 97L will have:

A)Yellow Circle
B)Orange Circle
C)Red Circle
D)No Circle


A) Yellow
388. canesrule1 04:43 PM GMT del 20 Luglio 2009    
Quoting Drakoen:
Let's play the game:
In the next TWO 97L will have:

A)Yellow Circle
B)Orange Circle
C)Red Circle
D)No Circle
im going with A
390. K8eCane 04:43 PM GMT del 20 Luglio 2009    
B
Member Since: Aprile 26, 2006 Posts: 5 Comments: 2375
392. claimsadjuster 04:43 PM GMT del 20 Luglio 2009    
Quoting Drakoen:
Let's play the game:
In the next TWO 97L will have:

A)Yellow Circle
B)Orange Circle
C)Red Circle
D)No Circle


A
393. SomeRandomTexan 04:44 PM GMT del 20 Luglio 2009    
It just seems that every move that 97L makes that things just turn more favorable then before in front of it... kinda eery...
Member Since: Agosto 30, 2007 Posts: 0 Comments: 1814
394. serialteg 04:44 PM GMT del 20 Luglio 2009    
Quoting weatherwatcher12:

I'm watching it also


greetings my fellow wave watcher
Member Since: Agosto 22, 2006 Posts: 2 Comments: 1966
395. Seastep 04:44 PM GMT del 20 Luglio 2009    
They'll keep it at A for now... and I agree atm.
Member Since: Settembre 9, 2008 Posts: 6 Comments: 3406
396. canesrule1 04:44 PM GMT del 20 Luglio 2009    
Quoting BurnedAfterPosting:


A) Yellow
if i was the NHC i would go with orange because shear does decrease in the next 48 and this is looking better but they know a lot more then i do, lets leave it at that.
397. TampaSpin 04:44 PM GMT del 20 Luglio 2009    
Off topic some but, this is really fun to watch also....what a division.

American League

American League East
Team W L L10 Strk
Boston 55 36 6-4 L 2
N.Y. Yankees 54 37 6-4 W 3
Tampa Bay 51 41 7-3 W 3
Member Since: Settembre 2, 2007 Posts: 175 Comments: 19747
398. weathermanwannabe 04:44 PM GMT del 20 Luglio 2009    
Quoting StormW:


HI-RES satellite images very 3 hours.


Thank You..
Member Since: Agosto 8, 2006 Posts: 0 Comments: 6703
399. canesrule1 04:44 PM GMT del 20 Luglio 2009    
Quoting K8eCane:
B
bold choice, never know might happen.
400. TheDawnAwakening 04:45 PM GMT del 20 Luglio 2009    
What are everyone's thoughts on possible SE coast development end of this week? The favorable track would take it north, northeast up the coast and then out to sea.
Member Since: Ottobre 21, 2008 Posts: 215 Comments: 3159
401. weatherwatcher12 04:45 PM GMT del 20 Luglio 2009    
Quoting Drakoen:
Let's play the game:
In the next TWO 97L will have:

A)Yellow Circle
B)Orange Circle
C)Red Circle
D)No Circle

B, because there are westerlies in the island, the ULL is lifting north and the ASCAT showed some interesting winds.
Member Since: Maggio 16, 2009 Posts: 1 Comments: 1231

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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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