Invest 91L more organized, but has little time to develop

By: Dr. Jeff Masters , 2:31 PM GMT on April 22, 2011

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Hurricane season is more than a month away, but we have a tropical disturbance (91L) typical of what one might see in June or November. 91L is spinning over the waters a few hundred miles south of Bermuda, and has improved considerably in organization since yesterday, thanks to a drop in wind shear. The latest SHIPS model output is showing shear of 40 - 55 knots over 91L, but shear analyses from the University of Wisconsin CIMSS group is showing lower shear values of 20 - 30 knots over the main circulation center and to 91L's north, where the heaviest thunderstorms are. The system has a warm core at low levels, but a trough of low pressure lies over the storm at upper levels, and this trough is pumping cold, dry air into 91L, making it not completely tropical. One characteristic of subtropical systems like 91L is the presence of the main band of heavy thunderstorms removed several hundred miles from the circulation center, and 91L fits that description. 91L has two centers of circulation competing to be dominant, and this competition is slowing the storm's development. The storm was headed north at 5 - 10 mph early this morning, but that motion has halted, and 91L appears to be moving more south-southwesterly now, away from Bermuda. Sea surface temperatures are 23°C, which are very cold for a tropical storm to form in, but could support development of a subtropical storm.

As 91L moves south today, shear will steadily rise, and the storm likely has only until Friday night before shear grows too high to permit development. NHC is giving 91L a 20% chance of developing into a subtropical or tropical depression, which is a reasonable forecast. There has been only been one named April storm in the Atlantic since 1851, Tropical Storm Ana of 2003. The formation of a tropical disturbance at this location this time of year is unusual, but is not a harbinger of a active season ahead. Had this been going on in the Caribbean, that would be a different story.


Figure 1. Morning satellite image of the Atlantic tropical disturbance 91L. Note the two centers of circulation competing to be dominant. I expect the northern center will become dominant.

Jeff Masters

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Quoting hydrus:
Yes it is..Would you please tell him to cut it out.


He's been avoiding me lately. Must have been something I said.
Member Since: Posts: Comments:
Quoting KrippleCreekFerry:
We feel this season will be below average to average. La Nina is abating and wind shear will be going up. We do see an active Pacific season. Things could change so stay tuned for updates.


May I enquirer who "we" is?
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Well, just read back through the blog, actually saw some glints of humor, here and there....thank goodness !....It's all gonna be Otay....as for as the weather....here in Ms the humidity is smothering, makes me wanna move north for the summer......naaah......lol
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Quoting emcf30:


Live in South Orlando on Lake Conway now. Lived in Melbourne for awhile, Move backed to O-town after Frances and Jeanne redecorated my house
Redecorated.lol... In 1983 I was visiting Melbourne when T.S.Barry was suppose to cause a ruckus but fizzled before moving ashore.
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Quoting aquak9:


(quick google search)

OOO!!! I know what's going on my Christmas wish list!

ok ya'll, I'm probably upsetting some with the poor humor here. Sorry- no offense intended. My heart is tore UP with the weather horrors from the past ten days. Bad reaction, to bad situations.

Peace, prayers, love your families.


Though appreciated for sure, there are no apologies necessary. Humor is a very natural reaction to stress.

If you get a chance research some of the things pilots say during emergencies. (...and they are some of the more professional and responsible individuals around.)
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Looks like the next round is going to be further south
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Quoting hydrus:
48 years is a long stretch of time sure..What part of Florida may I ask.?


Live in South Orlando on Lake Conway now. Lived in Melbourne for awhile, Move backed to O-town after Frances and Jeanne redecorated my house
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Quoting emcf30:


Better yet I have a Plasma cutter. Talking about a E ticket ride


(quick google search)

OOO!!! I know what's going on my Christmas wish list!

ok ya'll, I'm probably upsetting some with the poor humor here. Sorry- no offense intended. My heart is tore UP with the weather horrors from the past ten days. Bad reaction, to bad situations.

Peace, prayers, love your families.
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Quoting emcf30:


Yea, lived in Florida 48 years. Good question. May be there for awhile.
48 years is a long stretch of time sure..What part of Florida may I ask.?
Member Since: September 27, 2007 Posts: 1 Comments: 21507
Quoting aquak9:
CV- yeah here we are looking at another possible neutral, and there's our list of names, too. Geeez.

Nope, can't handle another '05. Fukushima ain't got nuthin' to compare to the meltdowns we'd see here on WU.


LOL!!! Thanks, That made my night. Have a good evening all.
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Quoting aquak9:
I have a sweet chainsaw...it could be a convertible shuttle bus.


Better yet I have a Plasma cutter. Talking about a E ticket ride
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Quoting Grothar:


Stay cool, hydrus. Drop back later if you can. Still stormy by you I see.
Yes it is..Would you please tell him to cut it out.
Member Since: September 27, 2007 Posts: 1 Comments: 21507
I have a sweet chainsaw...it could be a convertible shuttle bus.
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Quoting aquak9:
emcf30- are you in florida?

ok, now how are they gonna get that shuttle bus back down? Wait for another tornado?


Yea, lived in Florida 48 years. Good question. May be there for awhile.
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Quoting aquak9:
Wilma bomb night will stick in my head forever.

I did not stay up for that, but found out about it, at like 5am. Yes I remember clearly that moment, like "this just can't be happening..."

Thanks for the storm reports/news from St. Louis. So many Easter travelers, and after the evening they just had a few days ago...geez their emergency responders must be worn OUT.

Injuries from glass sounds minor- but it ain't. That's a hospital trip usually, ahhh what a mess. Prayers up.


Indeed, Prayers up, seems like all the time now.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
Man they have been trying to get some children that entrapped in their basement for along time now. Just sent another 5 engine companies to assist. Hope they are alright
Member Since: August 7, 2010 Posts: 0 Comments: 1937
emcf30- are you in florida?

ok, now how are they gonna get that shuttle bus back down? Wait for another tornado?
Member Since: Posts: Comments:

here we go again.
Loop
Member Since: July 11, 2006 Posts: 14 Comments: 11358
Incident Description
TRAFFIC ADVISORY
04/22/11 21:25 (MARYLAND HEIGHTS - ) I-270 CLOSED DUE TO DEBRIS AND POWER LINES DOWN FROM TORNADO, UTILTIES & POLICE DEPARTMENT ON SCENE [ILL113]
TRAFFIC ADVISORY
04/22/11 21:10 (ST. LOUIS - ) POLICE DEPARTMENT ON SCENE WITH 2-3 18 WHEELERS ROLLED OVER DUE TO A TORNADO CHECKING ON INJURIES I-70 CLOSED [LOU014]
SEARCH & RESCUE
04/22/11 21:06 (BERKELEY - ) UPDATE: COMMAND/INCIDENT COMMANDER ADVISING HEAVY DAMAGE TO HOUSES IN 2 BLOCK RADIUS WITH MULTIPLE ENTRAPMENTS, MULTI MUTUAL-AID REQUEST [ILL113]
TECHNICAL RESCUE
04/22/11 21:04 (BERKELEY - ) 1 STY HOUSE HIT BY TORNADO, 1 VICTIM TRAPPED INSIDE, FIRE DEPARTMENT ON SCENE [ILL113]
SEARCH & RESCUE
04/22/11 21:00 (FERGUSON - ) AT LEAST 2 HOUSES STRUCK BY TORNADO, SEARCH IN PROGRESS, FIRE DEPARTMENT ON SCENE [ILL113]
Member Since: Posts: Comments:
Believe it or not. They are saying that the shuttle bus pic I posted earlier hanging off the top of the parking garage was actually picked up from ground level and dropped on top of the wall. WOW. It does make sense though because your typical parking garage that type of vehicle could not drive thru it. To tall.
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Wilma bomb night will stick in my head forever.

I did not stay up for that, but found out about it, at like 5am. Yes I remember clearly that moment, like "this just can't be happening..."

Thanks for the storm reports/news from St. Louis. So many Easter travelers, and after the evening they just had a few days ago...geez their emergency responders must be worn OUT.

Injuries from glass sounds minor- but it ain't. That's a hospital trip usually, ahhh what a mess. Prayers up.
Member Since: Posts: Comments:
Quoting aquak9:
CV- yeah here we are looking at another possible neutral, and there's our list of names, too. Geeez.

Nope, can't handle another '05. Fukushima ain't got nuthin' to compare to the meltdowns we'd see here on WU.


Ha Ha, so true. I remember avoiding this blog like the plague in 05, stayed in weatherguy03's blog.

I could do it again. Far more knowledgeable now as well. Wilma bomb night will stick in my head forever. Never had that much adrenalin going. Real time recon, thought we lost em.... Good Times.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
0134 ST. ANN ST. LOUIS MO 3873 9039 TRACTOR TRAILERS STANDING ON END. (LSX)
0143 BRIDGETON ST. LOUIS MO 3877 9043 AIR NATIONAL GUARD BUILDING DAMAGED ... AND STRUCTURAL DAMAGE TO BUILDINGS AT THE AIRPORT ... AND CARS FLIPPED (LSX)
0148 FERGUSON ST. LOUIS MO 3875 9030 2 LARGE TREES DOWN ... AND MANY 1-5 INCH LIMBS DOWN (LSX)
0153 BRIDGETON ST. LOUIS MO 3877 9043 MAIN TERMINAL WINDOWS BLOWN OUT AT LAMBERT AIRPORT ... .ROOF OFF OF CONCOURSE C ... AND POWER OUTAGES
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Link

Link

Here is a couple aquak9
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Quoting aquak9:
re- damage at lambert field

anyone gotta link to verification of damage intensity?


Weather channel and here.

http://www.ksdk.com/news/article/255883/3/Heavy-s torms-batter-St-Louis-area

edit: iReport pictures I just found
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Just local news reports ATM.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
CV- yeah here we are looking at another possible neutral, and there's our list of names, too. Geeez.

Nope, can't handle another '05. Fukushima ain't got nuthin' to compare to the meltdowns we'd see here on WU.
Member Since: Posts: Comments:
Quoting Grothar:
Just got word that the CIMSS website has been fixed. Here is the first image. Notice the 100kt windshear.


oh my
say bye bye to 91L
Member Since: August 24, 2010 Posts: 19 Comments: 4358
Quoting KEEPEROFTHEGATE:
few more months then we will see those 20lb wimps turn into monster nightmares




91L was a good primer.. Surely not ready for the biggies yet. It's been a while since we've tracked a neutral year, not sure I am ready for that, lol.


2009 *El Nio -3.87 * see documentation
2008 La Nia 10.15
2007 *La Nia 3.35 * see documentation
2006 El Nio -8.68
2005 Neutral 1.45
2004 El Nio -7.45

Obviously 2010 was La Nina
Member Since: January 30, 2010 Posts: 0 Comments: 3259
re- damage at lambert field

anyone gotta link to verification of damage intensity?
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Well, we in S.E. Texas have a 20% chance of rain on Tuesday and Wednesday. WOOO-HOOOO! Hopefully we get at least SOME drought relief.
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Quoting BahaHurican:
re 463: that frontal line looks furious.... makes 91L look like a 20lb wimp...
few more months then we will see those 20lb wimps turn into monster nightmares
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Quoting BahaHurican:
Now THIS looks promising....

Sunday
84 | 73° F Chance of Rain
20% chance of precipitation
Monday
86 | 73° F T-storms
100% chance of precipitation
Tuesday
86 | 73° F Chance of T-storms
40% chance of precipitation

Sure hope it works out. It's been a while since I've seen a 100% rain chance in our forecast...



Dwindling here, lol, every day it gets more bleak. From the Miami NWS

AS THE BEGINNING OF NEXT WEEK APPROACHES, THE INVERTED TROUGH WILL
MOVE THROUGH SOUTH FLORIDA. THIS WILL CONTINUE TO INCREASE THE MOISTURE
AND INSTABILITY OVER THE AREA. THEREFORE...WE MAINTAINED THE
CHANCE OF SHOWERS AND THUNDERSTORMS FOR EARLY TO MIDDLE OF NEXT
WEEK OVER SOUTH FLORIDA. MODELS ARE STILL IN AGREEMENT IN SHOWING
THAT THERE COULD BE ENOUGH INSTABILITY DURING THE MONDAY/TUESDAY
TIME FRAME TO ALLOW FOR SOME THUNDERSTORMS. SO WILL CONTINUE THE CHANCES
OF SHOWERS AND THUNDERSTORMS DURING THIS TIME. RAINFALL AMOUNTS
STILL DO NOT LOOK TO BE THAT SUBSTANTIAL TO RELIEVE THE DROUGHT,
BUT WILL HELP TO REDUCE SOME OF THE RAINFALL DEFICITS THAT
CURRENTLY EXIST ACROSS SOUTH FLORIDA.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
re 463: that frontal line looks furious.... makes 91L look like a 20lb wimp...
Member Since: October 25, 2005 Posts: 19 Comments: 22359
Same storms in Missouri and Illinois and gonna bring some severe storms to me.

OVERNIGHT - Showers and thunderstorms. Some thunderstorms may produce damaging winds and large hail this evening. Locally heavy rainfall possible. Lows in the upper 50s. Temperatures rising into the mid 60s. South winds 10 to 15 mph. Chance of rain 100 percent.
Member Since: Posts: Comments:
466. flsky
President Declares A Major Disaster for Oklahoma

Release Date: April 22, 2011
Release Number: HQ-11-040

WASHINGTON, D.C. -- The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) today announced that federal disaster aid has been made available to Oklahoma to supplement the state and local recovery efforts in the area struck by severe storms, tornadoes, and straight-line winds on April 14, 2011.

The President's action makes Federal funding available to affected individuals in Atoka county. Assistance can include grants for temporary housing and home repairs, low-cost loans to cover uninsured property losses, and other programs to help individuals and business owners recover from the effects of the disaster.

Federal funding is also available on a cost-sharing basis for hazard mitigation measures statewide.
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Re: 461. Does make one hope that West Coast sites like ours and NRL have mirror sites on the east coast or in the Midwest in case of severe earthquake disruption. (reverse is also true for NHC in case of severe hurricane disruption)
Member Since: October 25, 2005 Posts: 19 Comments: 22359
Quoting Ameister12:

That's terrible! I hope it's nothing like the tornado in Raleigh.



Sounds pretty bad to me, their all bad IMO. Every tornado has it's own calling card, regardless of size.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
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Now THIS looks promising....

Sunday
84 | 73° F Chance of Rain
20% chance of precipitation
Monday
86 | 73° F T-storms
100% chance of precipitation
Tuesday
86 | 73° F Chance of T-storms
40% chance of precipitation

Sure hope it works out. It's been a while since I've seen a 100% rain chance in our forecast...
Member Since: October 25, 2005 Posts: 19 Comments: 22359
Off topic by interesting and scary at the same time
(AP)

PETERSON AIR FORCE BASE, Colorado - The Air Force said computer links with some U.S. bases in the Pacific were severed by the earthquake and tsunami that hit Japan on March 11, but one of its cyber squadrons restored them within five hours.

The Air Force said Thursday that bases in Japan, Korea and Guam were affected. It wasn't immediately clear what the consequences were.

The 561st Network Operations Squadron in Hawaii coordinated the repairs. The squadron is part of a unit at Peterson Air Force Base in Colorado. The Air Force Space Command, which ultimately oversees all Air Force cyber operations, is also based at Peterson.

The Air Force says the Hawaii squadron also canceled planned interruptions for maintenance on Pacific computer networks so they would remain open.
Member Since: August 7, 2010 Posts: 0 Comments: 1937
Incident Description
TECHNICAL RESCUE
04/22/11 20:56 (MOLINE ACRES - ) HOUSE STRUCK BY TORNADO, VICTIM TRAPPED IN BASEMENT, FIRE DEPARTMENT ON SCENE [ILL113]
MAJOR ACCIDENT
04/22/11 20:54 (BRIDGETON - ) UPDATE: COMMAND/INCIDENT COMMANDER REPORTS POWER LINES DOWN ACROSS WEST-BOUND I-70, 2 BIG RIGS ROLL-OVER, MINOR INJS, WEST-BOUND 70 CLOSED [ILL113]
MAJOR ACCIDENT
04/22/11 20:48 (BRIDGETON - ) BIG RIG ROLL-OVER MOTOR VEHICLE ACCIDENT, MINOR INJS, TORNADO POSSIBLY BLEW TT OVER BUT UNCONFIRMED, FIRE DEPARTMENT ON SCENE [ILL113]
SPECIAL
04/22/11 20:43 (FERGUSON - ) ROOF COLLAPSE IN A 1 STY HOUSE, OCCUPANTS OUT, NO INJS, FIRE DEPARTMENT ON SCENE [ILL113]
SEARCH & RESCUE
04/22/11 20:17 (MARYLAND HEIGHTS - ) MULTIPLE HOMES HIT BY A TORNADO, REPORTS OF MULTIPLE ENTRAPMENTS, 2ND ALM REQUESTED [ILL113]
Member Since: Posts: Comments:
Quoting BahaHurican:
I was really hoping for 1-2 inches between Sun and Tues... just enough to give the ground a thorough wetting down....

Anyway, it ain't over til the fat lady sings, and I don't hear any women singing right now....



A lot can happen between now and then. COC is still kicking harder than ever, although void of much convection. I think our best hope is a little extra instability to kick off the lagging natural forces. Our locals in WPB, FL are growing less optimistic however, as am I.

Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting CyclonicVoyage:


Extensive damage reported @ Lambert Int. Airport. Glass blown into terminal C, minor injuries reported and another terminal with damage. Homes destroyed multi level buildings collapsed with people trapped. 2 confirmed tornado's, one north & one south of downtown.

That's terrible! I hope it's nothing like the tornado in Raleigh.
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XX/INV/91L
MARK
24.85N/64.11W
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Quoting Ameister12:
What's going on in St. Louis. I heard a tornado hit there.


Extensive damage reported @ Lambert Int. Airport. Glass blown into terminal C, minor injuries reported and another terminal with damage. Homes destroyed multi level buildings collapsed with people trapped. 2 confirmed tornado's, one north & one south of downtown.
Member Since: January 30, 2010 Posts: 0 Comments: 3259

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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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