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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Quoting CybrTeddy:
Judging if the models are correct with this blob,
90L could be declared at any time.


I have a feeling that we'll have 90L and possibly 91L tomorrow.

That storm out over the Atlantic is looking more and more subtropical. The caribbean blob is starting to look circular.
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Good evening to all. Thought I saw Zoo post, if so hello Zoo. This system is really taking us for a little pre-season run..I'm just glad its May and not late summer.
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Blog Statistics:

2335 comments and 40 entries posted by all members in the last 24 hours.
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
And there's no low pressure area as of yet
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Judging if the models are correct with this blob,
90L could be declared at any time.
Member Since: July 8, 2005 Posts: 259 Comments: 24574
Quoting WeatherStudent:
Are you finding this low pressure area to west all of the convection, towards east of all of the convection, or inside of the actual convection? help me out here, please.


Convection on the east
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Some rotation in the clouds are seen in this radar from Pilon,Cuba.

img

Link
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Mid-level winds support a broad circulation seen on satellite imagery. In addition, 500 mb vorticity has increase along this feature.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
LOL Beell!
Member Since: October 28, 2006 Posts: 57 Comments: 30825
723. beell
I need to apologize to all our non-caucasian blogers. Sorry. I have removed the post!
)
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722. JLPR
here we go again
long time since I have posted here
but we seem to be starting already? =S
this is nuts
Atlantic go to sleep until at least mid July! lol

well the most interesting one seems to be the Low in the Bermuda area, the one south of Cuba is being attacked by wind shear and the one that is yet to form .... ummm pretty active

Blob hunt! xD
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Quoting hahaguy:
Ok I'm a little confused here , but it's probably from the rum and coke's.
Quoting hahaguy:
Ok I'm a little confused here , but it's probably from the rum and coke's.


And the night is young ....

BTW - very little rain so far in the lower Keys from this "Blob of interest" near Cuba. time will tell
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i'm new here! where can i go to study up for pre-season?
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You didn't see that.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
Quoting WeatherStudent:


I'll consider that, will you, blogger?


I will be here through witch hour good sir.
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Quoting zoomiami:


Hi Haha - I'm confused and there are no rum & cokes involved!

Ok good to know it's not the drinks lol.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
The GFS 18z initialization looks more appropriate.
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Quoting Drakoen:
There's nothing wrong with... abreast.


I just knew Mr vocabulary himself would come to the rescue!

LOL, Drak, just a-yankin your chain.
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It doesn;t seem it will be extratropical in nature:



But cool in the upper levels, warm at in the lower levels

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting hahaguy:
Ok I'm a little confused here , but it's probably from the rum and coke's.


Hi Haha - I'm confused and there are no rum & cokes involved!
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There's nothing wrong with... abreast.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
Link mobile ala. discussion
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Member Since: July 15, 2006 Posts: 178 Comments: 56059
Ok so Accuweather Met Frank Strait doesn't believe it will get a name and Mike from FLHurricane is thinking Subtropical. The chances are slim for this to get a name, but not 10%.. more like 30-40% at this time. the disturbance has actually organized a bit more since this afternoon and I believe it will get tagged tomorrow sometime and we will all have the joy of seeing the 2 other models. I can see how this goes to South Florida then to the GOM. Temperatures are warm enough to support a Subtropical system so I'm predicting a Subtropical system out of this mess.
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Quoting beell:


I shall patiently await your "becoming abreast"...
roflol
Member Since: July 15, 2006 Posts: 178 Comments: 56059
Ok I'm a little confused here , but it's probably from the rum and coke's.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
705. beell
Quoting beell:


I shall patiently await your "becoming abreast"...


Course there is always the chance you could become something else!
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Member Since: July 15, 2006 Posts: 178 Comments: 56059
????
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting WeatherStudent:
I'll arise out of bed very early tomorrow to become abreast by y'all about any new overnight development in regards to our soon to be storm.


How about a return for witch hour.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
SSD did some serious upgrades.
That will help big time come the Big Uns.
Member Since: July 3, 2005 Posts: 428 Comments: 129841
697. beell
Quoting WeatherStudent:
I'll arise out of bed very early tomorrow to become abreast by y'all about any new overnight development in regards to our soon to be storm.


I shall patiently await your "becoming abreast"...
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Gulf Of Mexico - Water Vapor Enhanced Overlay Loop
Member Since: July 3, 2005 Posts: 428 Comments: 129841
The 00z NAM looks like it's putting the system a bit further west than it is currently.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
hey look its JFV
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Some changes made on SSD:
Link

We can get microwave imagery, precip rates, pwats, sfc winds, etc.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
689. IKE
System looks a little better on satellite. Caribbean system.
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Quoting KEEPEROFTHEGATE:
yeah not a good sign


Whats not a good sign?
Member Since: September 7, 2008 Posts: 17 Comments: 1604

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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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