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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Member Since: August 7, 2010 Posts: 0 Comments: 1933
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE TULSA OK
621 PM CDT FRI APR 22 2011

THE NATIONAL WEATHER SERVICE IN TULSA HAS ISSUED A

* TORNADO WARNING FOR...
NORTHWESTERN ADAIR COUNTY IN NORTHEAST OKLAHOMA
SOUTHEASTERN DELAWARE COUNTY IN NORTHEAST OKLAHOMA
WESTERN BENTON COUNTY IN NORTHWEST ARKANSAS

* UNTIL 700 PM CDT

* AT 617 PM CDT...NWS METEOROLOGISTS AND STORM SPOTTERS WERE TRACKING
A VERY DANGEROUS TORNADO LOCATED 3 MILES NORTHEAST OF KANSAS...
MOVING EAST AT 35 MPH. A TORNADO HAS BEEN CONFIRMED...TAKE COVER
NOW!

* SOME LOCATIONS IN OR NEAR THE PATH OF THIS STORM INCLUDE...
COLCORD...MAYSVILLE...WEST SILOAM SPRINGS...SILOAM SPRINGS...
GENTRY...DECATUR...GRAVETTE...SPRINGTOWN...HIGHFIL L AND HIWASSE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE NEAR THE PATH OF THIS STORM...TAKE COVER NOW! IF NO
UNDERGROUND SHELTER IS AVAILABLE MOVE TO AN INTERIOR ROOM ON THE
LOWEST FLOOR. MOBILE HOMES AND VEHICLES SHOULD BE ABANDONED FOR MORE
SUBSTANTIAL SHELTER. AVOID WINDOWS!

IN ADDITION TO A TORNADO...THIS STORM IS CAPABLE OF PRODUCING GOLF
BALL SIZE HAIL AND DESTRUCTIVE STRAIGHT LINE WINDS. IF NO
UNDERGROUND SHELTER IS AVAILABLE TAKE COVER ON THE LOWEST FLOOR IN
AN INTERIOR ROOM AWAY FROM WINDOWS.



LAT...LON 3649 9429 3621 9426 3621 9433 3615 9434
3614 9440 3616 9480 3617 9480 3617 9483
3636 9483 3644 9461
TIME...MOT...LOC 2321Z 265DEG 29KT 3623 9472

Member Since: August 7, 2010 Posts: 0 Comments: 1933
Quoting PlazaRed:
Hydrus!!
Ive got the Face! If you have got the
Punch?
Please give your coordinates and I will be there to recive the Blow!!
. The only punch I have has 11 bottles of grain alcohol in it..I am concerned about how much severe weather we may face early next week......More may be required around that time..
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting sammywammybamy:
91L Facebook Fan Page:

Link


That is actually a good ideal. may come in handy when the conus is threatened by a hurricane.
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Hydrus!!
I Have removed this comment.I am sorry for being over reactive.
Member Since: January 21, 2011 Posts: 0 Comments: 2076
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting alfabob:


I think if they really wanted to promote public safety and scientific research then they should really think about switching things up. Obviously they have made mistakes in the past, but it seems they are more along the lines of not changing their opinions even if they are clearly incorrect (by their own guidelines). I remember last season where they were tracking the wrong LLC for a while (and switched back and forth as if they were the same thing) with one storm, and another where they didn't effectively give warning (Tomas). Plus there are people out there giving the correct observations for absolutely free. I would think if all of this funding is being dumped into their budget they should start picking up the slack. All I really want is for any cyclone in the Atlantic which is removing heat from the ocean to be properly recorded, so that the data is useful scientifically.
Yea. You can see why Politicians were considering cutting the budget for the NWS
Member Since: Posts: Comments:
Quoting stormpetrol:
Is it time to name 91L, sure looking more impressive than some named systems we had in the past even if its hybrid , STS.
Ahh yes..Bloggers are returning .Hope you are well S.P.
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting sammywammybamy:


to put out the wildfires... their really bad. The Everglades is... Dry.
You know its bad when the everglades are dry..It is considered a giant river..The Everglades are my old stomping grounds..We use to anchor on Shark River years ago...Fun but dangerous.
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Is it time to name 91L, sure looking more impressive than some named systems we had in the past even if its hybrid , STS.
Member Since: Posts: Comments:
Quoting TomTaylor:
There job isn't to create or not create media stirs.

There job, as far as I am aware, is to forecast and track Hurricanes in the Atlantic and E Pacific basins to promote public safety.

I'm not at all emotionally upset with the NHC, just logically frustrated - what they're doing is counterintuitive (there are numerous reasons to name this storm I already mentioned, and I can't think of any good reason not to name it other than their silly hidden criteria). If that makes sense.
There are storms that deserve names and designation for sure. But if they are not what they deem tropical or sub-tropical what do we get.? Noname storm....maybe..I think..
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting alfabob:
I think 91L will be liking what it finds west of 70W (if it makes it).



It will be a disintegrated open trough by then, if it makes it at all. Hopefully it manages to swing over Florida and give them some April showers.
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Quoting alfabob:
I think the NHC might just be having fun with everyone by not classifying it, or maybe trying not to cause a media stir by a rare April storm. Anyways you can see that the potential for subtropical formation in that region is higher than last year.


There job isn't to create or not create media stirs.

There job, as far as I am aware, is to forecast and track Hurricanes in the Atlantic and E Pacific basins to promote public safety.

I'm not at all emotionally upset with the NHC, just logically frustrated - what they're doing is counterintuitive (there are numerous reasons to name this storm which I already mentioned, and I can't think of any good reason not to name it other than their silly hidden criteria).
Member Since: Posts: Comments:
Quoting sammywammybamy:


Its all right... Same.. lately things have been rough..

The weather here has been rough also...I still cannot find time to pick up all the limbs. So I just mow around them...:0
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting sammywammybamy:


hydrus, how have ya been man?
I am sorry I butted into your post..I am having a rough day and should stick to weather.. I am ok.
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Member Since: July 15, 2006 Posts: 171 Comments: 53806
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE LOUISVILLE KY
625 PM EDT FRI APR 22 2011

THE NATIONAL WEATHER SERVICE IN LOUISVILLE HAS ISSUED A

* TORNADO WARNING FOR...
ANDERSON COUNTY IN EAST CENTRAL KENTUCKY...
SOUTHERN FRANKLIN COUNTY IN EAST CENTRAL KENTUCKY...
WESTERN WOODFORD COUNTY IN EAST CENTRAL KENTUCKY...
SOUTHEASTERN SHELBY COUNTY IN NORTH CENTRAL KENTUCKY...
EASTERN SPENCER COUNTY IN NORTH CENTRAL KENTUCKY...

* UNTIL 700 PM EDT...

* AT 622 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS
DANGEROUS STORM WAS LOCATED NEAR MOUNT EDEN...MOVING EAST AT 40
MPH. A FUNNEL CLOUD HAS BEEN SPOTTED WITH THIS STORM!

* THIS TORNADIC STORM WILL ALSO IMPACT...
LAWRENCEBURG...
GEE AND JUNTE...
BIRDIE AND ANDERSON CITY...
ALTON AND FOX CREEK...
STRINGTOWN AND NINEVAH...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.

TO REPORT DAMAGING WINDS...LARGE HAIL...OR FLOODING TO THE NATIONAL
WEATHER SERVICE...CALL TOLL FREE AT...1...8 7 7...6 3 3...6 7 7 2...
WHEN YOU CAN DO SO SAFELY.

&&

Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting hydrus:
I have respect for everyone...Even if they are not worthy of respect...Next week looks like a very severe weather event...
yep and i will be watchin and waiting
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting KEEPEROFTHEGATE:
it would not hurt to have respect for a forecaster from NHC even if they don't forecast the way you want but the way its mean to be forecasted in the end thats what matters correct forecast for conditions that are present
I have respect for everyone...Even if they are not worthy of respect...Next week looks like a very severe weather event...
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting TomTaylor:

Nonetheless, this hidden classification should be removed. OR if they do continue with the idea, they should add it to their definition of the minimum requirement for storms.

to expand on this:

Unfortunately, it is unlikely they will ever write out their hidden standards because these hidden standard are fairly subjective. Which is why, in my opinion hidden standards should be removed entirely.
Member Since: Posts: Comments:
Quoting hydrus:
lol..Yeah, I have always thought punching someone in the face was at the very least comical......
it would not hurt to have respect for a forecaster from NHC even if they don't forecast the way you want but the way its mean to be forecasted in the end thats what matters correct forecast for conditions that are present
Member Since: July 15, 2006 Posts: 171 Comments: 53806


Member Since: July 15, 2006 Posts: 171 Comments: 53806
Quoting sammywammybamy:


relax im just spreading comical relief bub.
lol..Yeah, I have always thought punching someone in the face was at the very least comical......
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting Stormchaser2007:
Oh well.

Made a good run at Arlene.




It actually does look like a small tropical storm on that particular sat pic...
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Quoting sammywammybamy:


I Just want to punch BEVEN in the face? what kind of parents name their child "BEVEN"... i mean come ON!


His name is Jack Beven. How much rain do you think so. Fla. will get from what's left of 91L?
Member Since: September 10, 2007 Posts: 0 Comments: 11150
Quoting hydrus:
Isnt that the last name of the forecaster.?


Yep his first name is Jack...
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Quoting MrstormX:


So do we just ignore systems out at sea? Basically that means we are ignoring a one-time meteorological event just so people don't become complacent. Obviously safety is a big issue, but scientific accuracy and reliability is as well.


Exactly.

One of the many benefits of satellites was the ability to track and record hurricanes way out to sea which would have otherwise gone unnoticed. Obviously, this is no hurricane, but its absolutely a sub tropical storm worthy of a name.

I know people tend to get overly excited on here since we're all weather enthusiasts and we occasionally become upset with the NHCs classification during the hurricane season. Ex: when a high end cat 4 doesn't reach cat 5 status, or a depression doesn't get a name as in this case.

However, I do feel this case is a little exceptional. Not only does it clearly meet the NHC written standards (clearly there are some hidden standards), but its also statistically important because this is such a rare occurrence.

Idk what's so hard about naming a storm...you'd think the NHC would be looking for stuff to do at this time of year. Id bet money that had this same storm been in the gulf of Mexico it would have been given a name.

Which gets back to the idea of hidden standards. NHC likes to factor in a threat value to its classification. Meaning storms threatening land, large populations or major shipping lanes are more likely to get a higher classification than a storm out in the middle of the Atlantic. This is not always the case, and infact rarely ever is. It really only becomes apparent with the naming of storms.

Nonetheless, this hidden classification should be removed. OR if they do continue with the idea, they should add it to their definition of the minimum requirement for storms.
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Quoting sammywammybamy:


I Just want to punch BEVEN in the face? what kind of parents name their child "BEVEN"... i mean come ON!
Isnt that the last name of the forecaster.?
Member Since: September 27, 2007 Posts: 1 Comments: 21183
Member Since: July 15, 2006 Posts: 171 Comments: 53806
XX/INV/91L
MARK
26.65N/63.75W
Member Since: July 15, 2006 Posts: 171 Comments: 53806
263. beell
Thanks all for the bunnytar comments. Certain other additions could be made but I am afraid of excessive wear & tear on the profile pic approvers.

I have plans for other holidays though...
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NHC did it again! Unnamed Subtropical Storm near the Bahamas.
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Beell - I think that bunny needs some jewelry.
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Quoting Patrap:
Nothing in a INVEST is ignored,,all resources combine to watch,log, and cover the System.

Relax..the Season will have many chances to go berserk.

of note,

Smaller 'cone of probability' cuts down on hurricane fear


After the hurricane center checked forecasts against what really happened last year, its margin of error for the five-day forecasts broke all records for accuracy, going back to when the center first began doing the five-day estimate in-house in 2001.

Last year's five-day forecasts were 65 miles better than the 2005-09 average. The three-day forecasts were 14.5 miles better. The one-day forecast was actually worse, by less than a mile, and the 12-hour forecast was off by 2.5 miles compared with the preceding five years.


That's impressive. They were pretty much on the money last year. With the models achieving new levels of development, skill certainly seems to be going up. Kudos to the NHC.

It's always interesting to follow the tropical forecasting professionals at NHC, and it's vital to listen to the NHC and local emergency officials when crisis approaches. I hope all blog followers are aware of that as the season gets underway.
Member Since: Posts: Comments:
Quoting CyclonicVoyage:




Yeah, me too. Hopefully the shear doesn't completely kill it. That's the trend this year though. Promised rain that never shows up or just enough to get the pavement wet. Anything attempting to move south of Lake O falls apart. The new sod I planted last spring is now hanging on by a thread and weeds have infiltrated once again, argggg.


I like this Guy!!
Member Since: January 21, 2011 Posts: 0 Comments: 2076
Hello again,

Beell that avatar is funny!

Sammy, I will have to check it out on FB when I get home tonight or next time I am on my home computer.

91L is still looking good; sure hope it brings some rain to South Florida.
Member Since: Posts: Comments:
257. SLU
000
ABNT20 KNHC 222131
TWOAT

SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
530 PM EDT FRI APR 22 2011

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

SHOWER ACTIVITY ASSOCIATED WITH A NON-TROPICAL LOW CENTERED ABOUT
430 MILES SOUTH OF BERMUDA HAS CHANGED LITTLE IN ORGANIZATION DURING
THE DAY. UPPER-LEVEL WINDS ARE BECOMING LESS CONDUCIVE FOR
DEVELOPMENT...AND THEY ARE FORECAST TO BECOME HIGHLY UNFAVORABLE
FOR DEVELOPMENT DURING THE NEXT 48 HOURS. THERE IS A LOW
CHANCE...10 PERCENT...OF THIS SYSTEM DEVELOPING INTO A SUBTROPICAL
OR TROPICAL CYCLONE DURING THAT TIME. THE LOW IS NOW MOVING TOWARD
THE WEST-SOUTHWEST AT ABOUT 10 MPH...AND A GENERALLY SOUTHWESTWARD
MOTION IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ADDITIONAL
INFORMATION ON THIS LOW CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED
BY THE NHC/TROPICAL ANALYSIS AND FORECAST BRANCH...UNDER AWIPS
HEADER NFDHSFAT2 AND WMO HEADER FZNT02 KNHC. ADDITIONAL SPECIAL
TROPICAL WEATHER OUTLOOKS WILL BE ISSUED AS NECESSARY.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BEVEN

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Quoting beell:
click-able





I feel awful for that region; Eastern Oklahoma, Arkansas, Missouri and Illinois seemingly get hit every other day.
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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.