Disturbance 91L spins towards Cape Hatteras; Cyclone Aila toll at 180

By: Dr. Jeff Masters , 1:28 PM GMT on May 27, 2009

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An area of disturbed weather, dubbed "91L" by the National Hurricane Center, is centered 120 miles south of Cape Hatteras, North Carolina. While the storm does not have much in the way of heavy thunderstorm activity, it does have a well-developed circulation, and the spin of the system is readily apparent on long range radar animations out of Morehead City, North Carolina. The disturbance is over waters of 25 - 26°C and has wind shear of 10 - 15 knots over it, and these conditions are marginally favorable for some slow development to occur until Thursday afternoon, when the system will begin moving over waters too cold to support tropical cyclone development. The disturbance will track north or north-northeastward at 10 - 15 mph towards North Carolina's Outer Banks today, then get swept northeastwards out to sea on Thursday. It is unlikely that the disturbance has enough time to develop into a tropical depression, but an Air Force hurricane hunter flight is on call to investigate the system this afternoon, if necessary. If the system does develop, the current location of the heaviest thunderstorm activity in a band well removed from the center suggests that 91L would be classified as a subtropical depression. The Outer Banks of North Carolina can expect 20 - 25 mph winds and heavy rain from this system tonight and Thursday morning. In a Special Tropical Weather Outlook issued at 8am EDT this morning, NHC gave 91L a low (less than 30% chance) of developing into a tropical depression.


Figure 1. Latest radar image from the Morehead City, NC radar.

Tropical Cyclone Aila death toll at 180
The year's deadliest tropical cyclone so far, Tropical Cyclone Aila, has killed at least 180 people in India and Bangladesh border region, according to the latest media reports. Aila hit the India/Bangladesh border region on May 25 as a borderline tropical storm/Category 1 hurricane, bringing sustained winds of 65 - 75 mph and a 3 - 4 meter (10 - 13 foot) storm surge to the coast. Aila has left over 150,000 homeless in India and 500,000 in Bangladesh. The cyclone destroyed over 180,000 homes in Bangladesh--a severe blow for a region still recovering from the devastation wrought by Category 4 Tropical Cyclone Sidr of November 2007, which killed 3,500 people. The death toll form Aila will likely go much higher, as over 500 people are still missing. The Bay of Bengal is no stranger to deadly cyclones--fifteen of the world's twenty deadliest tropical cyclones have been Bay of Bengal storms that have hit Bangladesh, India, or Myanmar. The most recent was last year's Cyclone Nargis, which killed 146,000 people in Myanmar.


Figure 2. Satellite image of Aila as it made landfall near the India/Bangladesh border. Image credit: NASA.

Interview tonight on hurricanetrack.com
I'll be doing one of my periodic spiels on Internet radio tonight at 9pm EDT. Tune your browsers to www.hurricanetrack.com and listen in to my interview with host Mark Sudduth. There is also a live chat to participate in. Hurricane season starts Monday!

Jeff Masters

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295. Skyepony (Mod)
1:32 AM GMT on May 28, 2009
Hey SJ~ Yeah not the usual twist. The CMC really holds off on any prefrontal blob & favored the frontal blob maybe developing East of FL & going NE. It didn't see this prefronal flare coming. I favor a high chance of a good soaking in FL.
Member Since: August 10, 2005 Posts: 156 Comments: 36167
294. TampaMishy
1:31 AM GMT on May 28, 2009
Hello everyone
Member Since: July 30, 2007 Posts: 0 Comments: 1474
293. AussieStorm
1:27 AM GMT on May 28, 2009
Member Since: September 30, 2007 Posts: 9 Comments: 15750
292. AussieStorm
1:18 AM GMT on May 28, 2009

Golden Gate Bridge


San Francisco Bay
Member Since: September 30, 2007 Posts: 9 Comments: 15750
291. StormJunkie
1:17 AM GMT on May 28, 2009
Evening Skye...I was avoiding mentioning that the GFS went kind of CMC on us...
Member Since: August 17, 2005 Posts: 26 Comments: 15472
290. StormJunkie
1:15 AM GMT on May 28, 2009
Evening bl, great to see you.

So you are saying the S word is in our favor? Been pretty busy lately so have not really checked the shear.
Member Since: August 17, 2005 Posts: 26 Comments: 15472
289. beell
1:14 AM GMT on May 28, 2009
An interesting side-note. Former 90L, way up over the Great Lakes may help drag the cold front offshore a bit.
Member Since: September 11, 2007 Posts: 137 Comments: 15353
288. Skyepony (Mod)
1:08 AM GMT on May 28, 2009
I know tommarrow's recon was cancelled. Today's may have been too. I'd think someone would be up by now.

Red water vapor gulf loop for watching that prefrontal trough flare up.


AGRICULTURE SMOKE IS NOTED OVER THE EASTERN BAY OF
CAMPECHE AND SPREADING N TO ALONG 24N BETWEEN 94W AND 87W. (stands out pretty well on the WV loop)

gfs actually has this blob hitting SWFL & a 2nd not yet developed one hitting Tampa not long after. Check out the 3rd little blob develop in the S Bahamas. GFS has Bermuda in the cross hairs this week.
Member Since: August 10, 2005 Posts: 156 Comments: 36167
287. beell
1:07 AM GMT on May 28, 2009
So for now all thoughts are on hold regarding a low approaching Tampa???

Hello, SJ. Some elements in place-long as we don't mention the "shear" word!
Member Since: September 11, 2007 Posts: 137 Comments: 15353
286. StormJunkie
1:04 AM GMT on May 28, 2009
So for now all thoughts are on hold regarding a low approaching Tampa???

For those that may not have seen, Portlight is responding to the Volusia County flood victims. Please help out if you can, any donation is the right amount!

Almost 1000 homes with major damage, mostly in low income areas.
Member Since: August 17, 2005 Posts: 26 Comments: 15472
285. KoritheMan
12:59 AM GMT on May 28, 2009
000
ABNT20 KNHC 272348
TWOAT
SPECIAL TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
745 PM EDT WED MAY 27 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

SHOWER ACTIVITY ASSOCIATED WITH THE AREA OF LOW PRESSURE CENTERED
ABOUT 90 MILES EAST-SOUTHEAST OF CAPE HATTERAS NORTH CAROLINA IS
DECREASING. THE LOW IS EXPECTED TO MOVE GENERALLY NORTHEASTWARD
AWAY FROM THE COAST AROUND 15 MPH OVER THE NEXT OR SO. CONDITIONS
ARE NOT FAVORABLE FOR SIGNIFICANT DEVELOPMENT...AND THE OPPORTUNITY
FOR THE SYSTEM TO BECOME A TROPICAL CYCLONE BEFORE REACHING COOLER
OCEAN WATERS CONTINUES TO DIMINISH. THERE IS A LOW CHANCE...LESS
THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS.

NO ADDITIONAL SPECIAL TROPICAL WEATHER OUTLOOKS ARE ANTICIPATED FOR
THIS SYSTEM.
SEE NATIONAL WEATHER SERVICE FORECAST OFFICE PRODUCTS
FOR ADDITIONAL INFORMATION.

$$
FORECASTER BERG/PASCH
Member Since: March 7, 2007 Posts: 521 Comments: 19143
284. tropicfreak
12:58 AM GMT on May 28, 2009
Quoting 2009hurricane:
What's the update from the HH from 91L?


I don't know but last I heard from the outlook there is less than 30% chance of it developing.
Member Since: September 2, 2006 Posts: 110 Comments: 6814
283. 7544
12:58 AM GMT on May 28, 2009
Quoting floridafisherman:
wow, some big storms popping up here in swfla. they are all training west to east. raining very heavy here with lots of lightning strikes. this storm reportly has hail, although i havent seen any yet.


true true thats what the stroms have been doing all week . ie now if the texas blob does turn into something its going to take the same route right over fla .
Member Since: May 6, 2007 Posts: 0 Comments: 6618
282. floridafisherman
12:41 AM GMT on May 28, 2009
wow, some big storms popping up here in swfla. they are all training west to east. raining very heavy here with lots of lightning strikes. this storm reportly has hail, although i havent seen any yet.
Member Since: August 28, 2005 Posts: 0 Comments: 547
281. KoritheMan
12:39 AM GMT on May 28, 2009
Quoting winter123:
You know what i never understand... If this storm had a cat 5 hurricane yesterday, then recurved to this location and looked like this, it would still be considered a TD even with the lack of convection. But since it's just now forming, it's not declared a TD. Why? (Or in general it takes a lot more to initiate advisories on a weak developing storm than it is to discontinue advisories on a weak former named storm)


That is something that I have wondered as well.
Member Since: March 7, 2007 Posts: 521 Comments: 19143
280. StormFreakyisher
12:37 AM GMT on May 28, 2009
Quoting StormJunkie:
Evening all

So what's the deal with the blob in the Gulf, and the low that the GFS has approaching Tampa in about 90 hours?

The blob in the gulf and the low that will go by Tampa the GFS shows is the same thing.
Member Since: May 16, 2009 Posts: 0 Comments: 684
279. ChrisDcane
12:34 AM GMT on May 28, 2009
Quoting bballerf50:


WOW...does it get anymore arrogant than that? Not the first time on this blog alone that you come off very pompous. Perhaps your upset that it is not winter anymore?

91L is much more complex than a surface low, by the way.


Ya look hows talking
278. StormJunkie
12:34 AM GMT on May 28, 2009
Evening all

So what's the deal with the blob in the Gulf, and the low that the GFS has approaching Tampa in about 90 hours?
Member Since: August 17, 2005 Posts: 26 Comments: 15472
277. ChrisDcane
12:29 AM GMT on May 28, 2009
Quoting WeatherStudent:


Thanks for telling me and thanks for the insult. It must make you really proud to treat others below your standards, doesn't it? Anyways......

Come on don't be so sensative he barely said anything
276. bballerf50
12:25 AM GMT on May 28, 2009
Quoting winter123:


Do you know how to read? it's in his post above:
"Interview tonight on hurricanetrack.com
I'll be doing one of my periodic spiels on Internet radio tonight at 9pm EDT."


WOW...does it get anymore arrogant than that? Not the first time on this blog alone that you come off very pompous. Perhaps your upset that it is not winter anymore?

91L is much more complex than a surface low, by the way.
Member Since: July 3, 2008 Posts: 0 Comments: 98
275. winter123
12:25 AM GMT on May 28, 2009
You know what i never understand... If this storm had a cat 5 hurricane yesterday, then recurved to this location and looked like this, it would still be considered a TD even with the lack of convection. But since it's just now forming, it's not declared a TD. Why? (Or in general it takes a lot more to initiate advisories on a weak developing storm than it is to discontinue advisories on a weak former named storm)
Member Since: July 29, 2006 Posts: 28 Comments: 1762
273. ChrisDcane
12:21 AM GMT on May 28, 2009


nothing on radar that leads me to believe it will develope
272. winter123
12:20 AM GMT on May 28, 2009
Quoting KEHCharleston:
Just learning...


Would someone look at about 70W 25N ??
IR loop (goes)

Shear, Vorticity, SST's favorable, right?
Is that another (dare I say it?) Bloblette?



saw that but i think its gonna die overnight
Member Since: July 29, 2006 Posts: 28 Comments: 1762
270. KEHCharleston
12:14 AM GMT on May 28, 2009
Just learning...


Would someone look at about 70W 25N ??
IR loop (goes)

Shear, Vorticity, SST's favorable, right?
Is that another (dare I say it?) Bloblette?

MODIFIED - 70-73W
Member Since: August 19, 2008 Posts: 6 Comments: 2490
269. chrisinkeywest
12:14 AM GMT on May 28, 2009
Hi, everyone

I've been reading along for a few years now and just wanted to say "Hi" and Thanks. We are gearing up for what, hopefully, will be a slow "season" here in Key West. Thanks for discussions and information.
Member Since: June 15, 2008 Posts: 0 Comments: 1
268. beell
12:14 AM GMT on May 28, 2009
Quoting tornadofan:


A true fact.


...a violent explosion...
Hey, tf!
Member Since: September 11, 2007 Posts: 137 Comments: 15353
267. futuremet
12:08 AM GMT on May 28, 2009
Quoting winter123:
Please stop wishcasting. What was over texas was simply a storm complex generated by a front over land. The only thing with a chance right now is 91L. Unless there's a surface low or decent model support within 24 hours... it's not going to develop.


you still have high hopes on this thing?
Member Since: July 19, 2008 Posts: 43 Comments: 4051
266. winter123
12:02 AM GMT on May 28, 2009
Quoting WeatherStudent:
Guys, at what time does Dr. Masters go on live on the air tonight?


Do you know how to read? it's in his post above:
"Interview tonight on hurricanetrack.com
I'll be doing one of my periodic spiels on Internet radio tonight at 9pm EDT."
Member Since: July 29, 2006 Posts: 28 Comments: 1762
265. futuremet
12:02 AM GMT on May 28, 2009
Quoting beell:


Well, we did leave out the pressure gradient part lol. But a cold front is a baroclinic zone that I can understand-sorta.


lol we answered simultaneously

As long you see a big change in temperature over a relatively short distance, then it is baroclinic...front.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
264. Cavin Rawlins
12:01 AM GMT on May 28, 2009
baroclinic enviroment is also characterize by wind shearing in the vertical. Or the maintenance convection due to such enviroment.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
262. tornadofan
12:00 AM GMT on May 28, 2009
Quoting beell:


Generate blog comments?


A true fact.
Member Since: April 5, 2007 Posts: 83 Comments: 12345
261. winter123
11:59 PM GMT on May 27, 2009
Please stop wishcasting. What was over texas was simply a storm complex generated by a front over land. The only thing with a chance right now is 91L. Unless there's a surface low or decent model support within 24 hours... it's not going to develop.
Member Since: July 29, 2006 Posts: 28 Comments: 1762
260. Seastep
11:58 PM GMT on May 27, 2009
That blob's trying to do something.

Pressure At 27W/95N - 29.72 -0.15

Link

Sync'd w/current sat (has ticked up since then)

Link
Member Since: September 9, 2008 Posts: 6 Comments: 3412
259. beell
11:58 PM GMT on May 27, 2009
Quoting futuremet:


It is basically a temperature gradient zone.


Well, we did leave out the pressure gradient part lol. But a cold front is a baroclinic zone that I can understand-sorta.
Member Since: September 11, 2007 Posts: 137 Comments: 15353
258. futuremet
11:53 PM GMT on May 27, 2009
Quoting gordydunnot:
Didn't Storm W explain baroclinic the other day.


It is basically a temperature gradient zone.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
257. beell
11:53 PM GMT on May 27, 2009
baroclinic
temperature gradient across a semi-short distance. Cold front is another term that most can relate to.
Member Since: September 11, 2007 Posts: 137 Comments: 15353
255. plywoodstatenative
11:52 PM GMT on May 27, 2009
All I know is for the past three days, each time around 1pm it starts hailing in downtown ft. lauderdale, just about clockwork to say it.
Member Since: November 15, 2005 Posts: 16 Comments: 4189
254. gordydunnot
11:50 PM GMT on May 27, 2009
Didn't Storm W explain baroclinic the other day.
Member Since: August 18, 2008 Posts: 0 Comments: 3109
253. futuremet
11:46 PM GMT on May 27, 2009
Quoting VAbeachhurricanes:




just thunderstorms from texas, should die as soon as the sun goes down


It will take a while, since this thing is generated by baroclinic energy.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
252. beell
11:44 PM GMT on May 27, 2009
Quoting plywoodstatenative:
any chance of that doing anything


Generate blog comments?
Member Since: September 11, 2007 Posts: 137 Comments: 15353
251. beell
11:40 PM GMT on May 27, 2009
850mb frontogenisis

Member Since: September 11, 2007 Posts: 137 Comments: 15353
Look out Florida its the Texas Blob not to be confused with the movie.
Member Since: August 18, 2008 Posts: 0 Comments: 3109
any chance of that doing anything
Member Since: November 15, 2005 Posts: 16 Comments: 4189
Quoting plywoodstatenative:
Someone do me a favor and pull the IR loop, whats the deal with that massive blow up of thunderstorms just off the coast of Louisiana?




just thunderstorms from texas, should die as soon as the sun goes down
Member Since: Posts: Comments:
247. beell
I would guess it is associated with a little 500mb wiggle over coastal TX. Note where the westerly winds make a shift to SW along the coast. Storms are underneath this little bit of vorticity.

RUC at 500mb (23Z at time of post)
Member Since: September 11, 2007 Posts: 137 Comments: 15353
Quoting plywoodstatenative:
Someone do me a favor and pull the IR loop, whats the deal with that massive blow up of thunderstorms just off the coast of Louisiana?


It is just an area of surface convergence of intense convection kindled by the instability of a baroclinic and dry line zone along eastern Texas. If you watch the IR loop, you will notice that the convection flare up originated from Texas. However, some of the computer models are expecting cyclogenesis to occur within this system. Even though the system is not close to the adjacent amplifying longwave trough, there appears to be ample PVA for good upper level divergence.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Someone do me a favor and pull the IR loop, whats the deal with that massive blow up of thunderstorms just off the coast of Louisiana?
Member Since: November 15, 2005 Posts: 16 Comments: 4189

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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.