Still watching for a potential early-season Atlantic subtropical storm

By: Dr. Jeff Masters , 7:10 PM GMT on May 16, 2009

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The latest 00Z and 12Z runs of the GFS, UKMET, NOGAPS, and ECMWF global dynamical computer models continue to indicate the possibility of an early season subtropical storm forming in the Gulf of Mexico 3 - 7 days from now. A modest area of low shear air is expected to open up between the polar jet stream to the north and the subtropical jet stream to the south, between Cuba and the northern Gulf of Mexico. The models have not been consistent with the timing or the size of this low shear area, and I wouldn't be surprised to see them back off again from this forecast with Sunday's set of runs. Nevertheless, I'll call once again for a 10% chance of development of a subtropical depression in the eastern Gulf of Mexico, 4 - 7 days from now. There isn't much of a disturbance at present to look at--there are some scattered showers between Cuba and Jamaica, but they are under a hefty 30 knots of wind shear. These showers should gradually increase in intensity and areal coverage over the next two days, and phase space diagrams from Florida State University indicate that an extratropical low may form near the western tip of Cuba 2 - 3 days from now. The storm may then gradually transition to a subtropical or tropical system later in the week, if the shear is low enough. Even if the shear is high and the storm remains extratropical, it could be a substantial rain-maker where it comes ashore. The models target the northern Gulf Coast between Louisiana and the Florida Panhandle as the most likely landfall location, but it is too early to place any confidence in this track.

There is also about a 10% chance a subtropical storm may form in the mid-Atlantic a few hundred miles east of Bermuda. There, a large upper-level cold low has cut off from the jet stream, and it may spin in place long enough over the next week to develop a warm core and be classified as a subtropical storm. It is unlikely that a subtropical storm forming that far out in the Atlantic this early in the year would pose a threat to any land areas, with the possible exception of Bermuda.

Climatology of early-season Atlantic tropical cyclones
Tropical storms are uncommon in the Atlantic before June 1, with only 26 named storms on record between 1851 - 2008. Five of these have made it to hurricane strength, and only one--Hurricane Able of 1951--made it to major hurricane status. Last year's Tropical Storm Arthur may be the deadliest May tropical cyclone on record. Though only a 40 mph tropical storm at landfall, Arthur killed five people in Belize and caused $78 million in damage. Three early-season storms have brought hurricane-force winds to land. The March 1908 hurricane swept through the northern Lesser Antilles Islands as a Category 1 or 2 hurricane, destroying at least 24 boats and causing damage to buildings on St. Bartholomew. Hurricane Able of 1951 brought sustained winds of 90 - 95 mph to the northern Bahama Islands, but caused little damage. Hurricane 2 of May 1908 hit North Carolina's Outer Banks as a Category 1 hurricane, but also caused little damage.


Figure 1. Tracking map for the earliest hurricane to make landfall, the March 1908 hurricane in the northern Lesser Antilles Islands.

List of all early season (formed in January - May) Atlantic named storms
May 31, 2008: Tropical Storm Arthur
May 6, 2007: Subtropical Storm Andrea
April 18, 2003: Tropical Storm Ana
April 21, 1992: Subtropical Storm 1
May 6, 1981: Tropical Storm Arlene
January 18, 1978: Subtropical Storm 1
May 21, 1976: Subtropical Storm 1
May 23, 1972: Subtropical Storm Alpha
May 17, 1970: Hurricane Alma (Category 1)
May 28, 1959: Tropical Storm Arlene
February 2, 1953: Tropical Storm Alice
May 25, 1952: Tropical Storm 1
May 15, 1951: Hurricane Able (Category 3)
May 22, 1948: Tropical Storm 1
May 19, 1940: Tropical Storm 1
May 27, 1934: Tropical Storm 1
May 14, 1933: Tropical Storm 1
May 5, 1932: Tropical Storm 1
May 13, 1916: Tropical Storm 1
May 24, 1908: Hurricane 2 (Category 1)
March 6, 1908: Hurricane 1 (Category 2)
May 27, 1890: Tropical Storm 1
May 16, 1889: Hurricane 1 (Category 1)
May 17, 1887: Tropical Storm 2
May 15, 1887: Tropical Storm 1
May 30, 1865: Tropical Storm 1

I'll have an update Sunday.

Jeff Masters

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Good Morning. This is my first post. Can someone bring me up to speed on what happened last night.
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1036. cg2916
Quoting TampaSpin:


MY Drink Blog.......hummmmmmmmm....LOL

Its not that long is it.......LOL

Didn't you say you had your own model? Where is it?
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Quoting txalwaysprepared:
Hey TS! Was just on your drink blog :)


MY Drink Blog.......hummmmmmmmm....LOL

Its not that long is it.......LOL
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Hey TS! Was just on your drink blog :)
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good morning
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Good Morning everyone
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Blog Refresh


Area of Interest #1


Area of Interest #2
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Quoting Weather456:
1024. hurricaneseason2006 8:51 AM AST on May 17, 2009

No I do not work for them.

Speaking of NHC

NHC to reference new experimental Saffir-Simpson Hurricane Wind Scale


Not sure how everyone feels about the sep. categorizations... but I think it's a great idea. I think it would have saved lives in Ike.
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1024. hurricaneseason2006 8:51 AM AST on May 17, 2009

No I do not work for them.

Speaking of NHC

NHC to reference new experimental Saffir-Simpson Hurricane Wind Scale
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Geeze, 06GFS is getting a little low happy for Florida. Showing 3 Lows in the Forecast period to traverse the state. I am not wishing for rain anymore, lol, we would be waterlogged for sure if this were to come true.
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howdy all, holey moley a blob already, free entertainment getting started early this year. This is not scientific but I recon it will go to the DR because the boss just flew down there to dive on our wreck we have in samana bay and the bad weather follows him every where, he has major bad karma weather wise LOL
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Analogue Forecasting
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ir. cloud top need to get alittle higher. any jamaica reports?
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Wait a minute!. Does Weather456 work for the NHC? This was posted on is blog at 5am:

There are no tropical waves analyzed at this time in the tropical Atlantic or over the mainland of Africa. The first tropical wave that emerged over the waters last week is not being analyzed by the Tropical Prediction center but based on continuation, TPW loops and low level infrared winds, the feature is most likely located near 40W, south of 10N.

Now look at:

1018. CybrTeddy 12:43 PM GMT on May 17, 2009
...TROPICAL WAVES...
A TROPICAL WAVE HAS BECOME MORE PRONOUNCED IN SHORTWAVE INFRARED
SATELLITE IMAGERY ALONG THE LINE FROM 11N40W TO 5N42W. IT IS
POSSIBLE THAT THIS WAVE WAS INTRODUCED INTO THE ANALYSIS A FEW
DAYS AGO AND THEN DROPPED BECAUSE IT WAS NOT ABLE TO BE DETECTED
IN OBSERVATIONS AND SATELLITE IMAGERY AT THAT TIME ANY MORE.
BROKEN TO OVERCAST MULTILAYERED CLOUDS ARE FROM 4N TO 12N
BETWEEN 36W AND 43W...AND FROM 6N TO 10N BETWEEN 43W AND 50W.
ITCZ PRECIPITATION IS FROM THE EQUATOR TO 3N BETWEEN 38W AND 46W.

For some reason, he always seems to be ahead of them.
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Hi all! It's been awhile! Haven't "seen" many of you in the off season... And now we are about to get started again. Crazy! We'll see if my nerves can handle another summer ;)
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Quoting CybrTeddy:
This is starting to gain Sub-Tropical characteristics.


Is it just me or does it look kinda dry?
Member Since: September 7, 2008 Posts: 17 Comments: 1604
1021. hahaguy
Wow I just looked at radar it has some really nice convection.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
This is starting to gain Sub-Tropical characteristics.
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Quoting Wundermet:
Severehurricane don't let it deceive you, it is highly disorganized


I know,
It doesn't even contain a LLC.
Convectivly speaking it is still looking healthier by the image.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
...TROPICAL WAVES...
A TROPICAL WAVE HAS BECOME MORE PRONOUNCED IN SHORTWAVE INFRARED
SATELLITE IMAGERY ALONG THE LINE FROM 11N40W TO 5N42W. IT IS
POSSIBLE THAT THIS WAVE WAS INTRODUCED INTO THE ANALYSIS A FEW
DAYS AGO AND THEN DROPPED BECAUSE IT WAS NOT ABLE TO BE DETECTED
IN OBSERVATIONS AND SATELLITE IMAGERY AT THAT TIME ANY MORE.
BROKEN TO OVERCAST MULTILAYERED CLOUDS ARE FROM 4N TO 12N
BETWEEN 36W AND 43W...AND FROM 6N TO 10N BETWEEN 43W AND 50W.
ITCZ PRECIPITATION IS FROM THE EQUATOR TO 3N BETWEEN 38W AND 46W.


Just thought to put that out there.

For the Caribbean.
A MIDDLE LEVEL TO UPPER LEVEL TROUGH EXTENDS FROM THE STRAITS OF
FLORIDA...ACROSS CUBA AND JAMAICA...INTO THE SOUTHWESTERN CORNER
OF THE AREA. THIS TROUGH HAS PERSISTED IN MORE OR LESS THE SAME
AREA FOR AT LEAST THE LAST 72 HOURS OR SO. A SURFACE TROUGH HAS
BECOME MORE PRONOUNCED IN SHORTWAVE INFRARED SATELLITE IMAGERY
ALONG 79W/80W FROM 16N TO 21N. MOIST UPPER LEVEL SOUTHWESTERLY
WIND FLOW IS ON THE EASTERN SIDE OF THE TROUGH ACROSS THE
REMAINDER OF THE CARIBBEAN SEA TO THE EAST OF 70W. THE CYCLONIC
FLOW AROUND THE TROUGH COVERS THE AREA ROUGHLY TO THE EAST OF
THE LINE FROM GUADELOUPE TO THE GUAJIRA PENINSULA OF
NORTHEASTERN COLOMBIA. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS ARE FROM 16N TO 20N BETWEEN THE JAMAICA
CHANNEL AND 78W.
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Good morning all... Maybe first Invest of the year?
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Severehurricane don't let it deceive you, it is highly disorganized
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1015. cg2916
Quoting SevereHurricane:
It blew up!
WOW

?
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1012

The winds does seem more cyclonic near the convection
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It blew up!
WOW
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting kmanislander:


Shear is actually what causes a center to relocate. If shear persists then we might see the center relocate to the SE of Jamaica where the heavy convection has been shunted to. If the shear continues to ease look for the convection to build back to the W between Jamaica and the Cayman Islands .

That is where the trough axis is and also where we see a rotation in the cloud field.


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1011. IKE
Latest image....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
1010. ackee
most of the showers is moveing east there is a slight spin SE of jamaica if this contiune dont see anything devloping from this system
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1009. IKE
Quoting kmanislander:
See you all later. Time to hit the links.


FOUR!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1008. cg2916
Looking a bit better... http://www.ssd.noaa.gov/goes/east/carb/loop-avn.html.
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1007. IKE
Quoting kmanislander:


No hills on the SW end of the island where I live. Flat as a table top LOL


Figures....:(

LOL...enjoy your golf KMAN.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
See you all later. Time to hit the links.
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Quoting kmanislander:


Shear is actually what causes a center to relocate. If shear persists then we might see the center relocate to the SE of Jamaica where the heavy convection has been shunted to. If the shear continues to ease look for the convection to build back to the W between Jamaica and the Cayman Islands .

That is where the trough axis is and also where we see a rotation in the cloud field.


If it does relocate beneath the convection mass, the track will shift further east. The 12z run will be interesting nonetheless.
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is there any possible way this could hit the florida peninsula. i'm in mobile,al
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Quoting IKE:


While I'm pushing a mower up and down a hill.:(

Lucky.



No hills on the SW end of the island where I live. Flat as a table top LOL
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1002. cg2916
Once the shear drops, the system should get more organized. At this point, it seems that only shear is holding it back.
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Quoting Wundermet:
Once shear decreases, there is a chance that the center will relocate, which will alter the model consensus.


Shear is actually what causes a center to relocate. If shear persists then we might see the center relocate to the SE of Jamaica where the heavy convection has been shunted to. If the shear continues to ease look for the convection to build back to the W between Jamaica and the Cayman Islands .

That is where the trough axis is and also where we see a rotation in the cloud field.
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Once shear decreases, there is a chance that the center will relocate, which will alter the model consensus.
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999. IKE
Quoting kmanislander:
Hi Ike

Yes we do. Clear skies, a gentle breeze and 1012 mb and rising. Perfect for my golf game this morning LOL


While I'm pushing a mower up and down a hill.:(

Lucky.

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:


Yeah, their about the same.


Exactly...It'll be interesting to see if these two particular runs are on to something. We shall see.
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Hi Ike

Yes we do. Clear skies, a gentle breeze and 1012 mb and rising. Perfect for my golf game this morning LOL
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996. IKE
Quoting Randyman:
This is kinda interesting...IKE compare the GFS 5/16/2009 12Z 096 Hour Forecast run @ 5/20/2009 12Z you posted back on Thursday's blog to...

Today's latest NAM 5/17/2009 06Z 078 hour Forecast run @ 5/20/2009 12Z (essentially the same forecast time)




49. IKE 11:05 AM CDT on May 14, 2009

12Z GFS @ 96 hours...



Link


Yeah, their about the same.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
995. IKE
KMAN...you have nice weather....

Owen Roberts, GC (Airport)
Updated: 13 min 38 sec ago
Partly Cloudy
81 °F
Partly Cloudy
Humidity: 79%
Dew Point: 73 °F
Wind: 9 mph from the East
Pressure: 29.89 in (Steady)
Heat Index: 85 °F
Visibility: 6.2 miles
UV: 1 out of 16
Clouds:
Few 1600 ft
(Above Ground Level)
Elevation: 10 ft
Member Since: June 9, 2005 Posts: 23 Comments: 37858
This is kinda interesting...IKE compare the GFS 5/16/2009 12Z 096 Hour Forecast run @ 5/20/2009 12Z you posted back on Thursday's blog to...

Today's latest NAM 5/17/2009 06Z 078 hour Forecast run @ 5/20/2009 12Z (essentially the same forecast time)




49. IKE 11:05 AM CDT on May 14, 2009

12Z GFS @ 96 hours...



Link
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In Bangladesh where i am now, the pressure is normally as low as 980mb like it is now! But that's only during the monsoon season.
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Quoting hurricanemaniac123:
Caribbean system looks better and better.

Same with the CATL systerm.

Subtropical storms on the way?

I wouldn't bet on the CATL system.
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990. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
morning, looks like we may have our first invest 90L this season!
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Caribbean system looks better and better.

Same with the CATL systerm.

Subtropical storms on the way?
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Regardless of if it becomes anything...it will bring us here in Florida...lots of rain...which we need badly!
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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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