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 TampaSpin:


Hey, are you looking over your shoulder at the RAYS yet.....there coming!


Great to see you guys starting to play well
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There is circulation in the mid levels of the atmosphere way south of jamaica in the latest loop
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Quoting canesrule1:
No way, the one in the atlantic is too dried out and no convection all it is, is just a swirling low.


Guess you weren't around for Andrea.
Lol. That was a dried STS, worse than that Extra/Sub Tropical Low in the Atlantic.
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Quoting TampaSpin:


So what is your difinition of a COC for Tropical development! Hummmmm


What does your model say... yes or no?
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Below is the 850mb Vorticity and you have to go all the way to 500mb Vorticity before anything shows......ITS WAY UP IN THE ATMOSPHERE....i would not even consider it a mid level spin...Look in the middle of the Atlantic there is a nice Vorticity return at the 850mb in the middle of the Atlantic.



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Quoting stillwaiting:
the circulation everyone's seeing in our blob is in the mid-levels, not the surface,don't be suprised if it gets torn apart in the next 12hrs....but then again the area has persisted for about 24hrs now!!!,I'd place my bets on a area forming in the central/south GOM area...


The Caribbean disturbance is going to get absorbed by the ULL coming in the Gulf.That's where the surface low will likely develop.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting TampaSpin:


So what is your difinition of a COC for Tropical development! Hummmmm
What???
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Quoting canesrule1:
to develop a COC


So what is your difinition of a COC for Tropical development! Hummmmm
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no LLC but a definitive mid level spin removed from the deepest convection.
Member Since: April 29, 2007 Posts: 0 Comments: 7708
Nothing anywere down there in regards to a surface circulation yet as the trough seems to be interacting with the fast upper level winds in the vicinity.Having seen any significant pressure drops in the area as of yet.
Member Since: May 14, 2006 Posts: 8 Comments: 13639
the circulation everyone's seeing in our blob is in the mid-levels, not the surface,don't be suprised if it gets torn apart in the next 12hrs....but then again the area has persisted for about 24hrs now!!!,I'd place my bets on a area forming in the central/south GOM area...
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Quoting TampaSpin:


70% chance for it develop into WHAT a named storm......WOW!
to develop a COC
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Quoting hurricanealley:
Looks like the caribbean blob is fading away imo


Hey, are you looking over your shoulder at the RAYS yet.....there coming!
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Quoting scottsvb:
There is no center in the carribean...not even close..the disturbance is a trough in the mid and upper levels

Over the next 24-36 hrs..a broad low will form near Cuba...and move N..exact location of the low is different in each model you look @. The low wont be fully @ the surface @ any time during the next 4-5 days. Pressures will drop over the gulf stream Tues into Weds...and a sub-tropical storm could be classified.. how strong this gets before coming ashore in eastern florida is too hard to guess..and once in the gulf..it has a chance to develop a warmer core Thurs into Friday.

Overall...its not there now or even during the next 24hrs.. everything you may see are not in the low levels...and by Monday..it will still be just becoming a large broad circulation..with a mid level low forming near cuba from this trough in the mid-levels. It wont pick up really any tropical char until Mon night into Tues once off the Keys or S Florida.


DiDo
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Quoting canesrule1:
in my opinion, ill give it a 70% chance, because its going under shear so that will make the center have to relocate possibly putting the COC where the deep convection is.


70% chance for it develop into WHAT a named storm......WOW!
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Looks like the caribbean blob is fading away imo
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check it out
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There is no center in the carribean...not even close..the disturbance is a trough in the mid and upper levels

Over the next 24-36 hrs..a broad low will form near Cuba...and move N..exact location of the low is different in each model you look @. The low wont be fully @ the surface @ any time during the next 4-5 days. Pressures will drop over the gulf stream Tues into Weds...and a sub-tropical storm could be classified.. how strong this gets before coming ashore in eastern florida is too hard to guess..and once in the gulf..it has a chance to develop a warmer core Thurs into Friday.

Overall...its not there now or even during the next 24hrs.. everything you may see are not in the low levels...and by Monday..it will still be just becoming a large broad circulation..with a mid level low forming near cuba from this trough in the mid-levels. It wont pick up really any tropical char until Mon night into Tues once off the Keys or S Florida.
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http://www.ssd.noaa.gov/goes/east/carb/jsl-l.jpg
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Quoting canesrule1:
No way, the one in the atlantic is too dried out and no convection all it is, is just a swirling low.


I guess we will see in time....
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Quoting TampaSpin:
Actually a Sub-Tropical storm is getting better organized in the Atlantic than the blob south......It is getting LLC going.
No way, the one in the atlantic is too dried out and no convection all it is, is just a swirling low.
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1066. cg2916
Quoting TampaSpin:
Actually a Sub-Tropical storm is getting better organized in the Atlantic than the blob south......It is getting LLC going.

Hmmm....
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Quoting TheCaneWhisperer:
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.

Wow, getting 2004 flashbacks. If the Bermuda high stays where it is now and the early season is this active Central Florida may be in for a rough time. Although I think is way too early to panic since all we have at this stage are models and not even an invest.
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in my opinion, ill give it a 70% chance, because its going under shear so that will make the center have to relocate possibly putting the COC where the deep convection is.
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Actually a Sub-Tropical storm is getting better organized in the Atlantic than the blob south......It is getting LLC going.
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I'll be watching the area of convection in the central/east GOM for our "system" to develop in this area w/a ULL first froming over the area....
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Quoting Tropicsweatherpr:


There is not a surface low yet.


Thanks. I really wanted to know because we are getting effects from this system right now
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thanks, looks like its coming to miami, where i live
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Good Morning. possible COC 17N/77.5W well removed from the deepest convection, in my opinion I think it has at least 30-50% chance of developing.
Member Since: April 29, 2007 Posts: 0 Comments: 7708
Well I'm ready for this year... with a new outlook on the season, that's for sure. I look forward to learning from all our regs.

Later!
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Quoting weatherwatcher12:
Does anybody know the exact center of the carib disturbance


There is not a surface low yet.
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Quoting canesrule1:
wundermet what's the link you get that from???


Link
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wundermet what's the link you get that from???
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Does anybody know the exact center of the carib disturbance
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Quoting canesrule1:
good morning, can anyone please show me the models of this wave around jamaica. Thanks


06Z



00Z

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Save this for the peak parts of Hurricane season!
Link
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good morning, can anyone please show me the models of this wave around jamaica. Thanks
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1049. Ossqss
As the novice hesitantly asks --- Is that a bit of outflow starting on this WV loop?

Link
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Quoting surfmom:
Ike -- up so early on a sunday morning???? must be something to look at.... hee, hee



nice waves for you yesterday SM,did you catch any????
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Beautiful Music by Ryan Farish, You can buy his albums online, I have a few.

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Quoting Ossqss:


Hi all, Just jumpin in for a few. Does our item in the Carrib, have any low level circulation yet? I have not had a chance to back read the 1000 entries yet :)


Tampa did you use your model for your picks?



Yes i used the model......if you look at the far tab at the bottom.....you can see what i choose for the Yearly Outlook and it coinsides with what i sent you....

Also nothing close to the lower levels yet.....everything is very high up at 500mb before anything appears....WAY UP THERE!
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1044. dearmas
Quoting TampaSpin:


Its actually a statisictically Model of inputted values to determine if conditions are are above or below average for development....its at my web site under the tab......TROPICAL PREDICTION ANALYSIS

Link


Did you see the 7 day rain for us in Tampa, wow lots of rain on the way
Member Since: August 23, 2006 Posts: 0 Comments: 120
What's new with the Caribbean disturbance. Did the Quickscat pick it up on its last pass
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Quoting TampaSpin:


LOL..Hey all you have left to do is clean the closet out....ROFLMAO


HAHA.. man I hope not. That was scary that day! But I would like some rain... NOTHING else. I'll be very specific about that this year.

Hey - the black dot in my avatar is my house lol ;)
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1041. Ossqss
Quoting TampaSpin:


Its actually a statisictically Model of inputted values to determine if conditions are are above or below average for development....its at my web site under the tab......TROPICAL PREDICTION ANALYSIS

Link


Hi all, Just jumpin in for a few. Does our item in the Carrib, have any low level circulation yet? I have not had a chance to back read the 1000 entries yet :)


Tampa did you use your model for your picks?

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Quoting txalwaysprepared:
Well TS, my avatar has changed this year. It used to be my nice little rainbow LOL. A bit of a change huh?


LOL..Hey all you have left to do is clean the closet out....ROFLMAO
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Quoting cg2916:

Didn't you say you had your own model? Where is it?


Its actually a statisictically Model of inputted values to determine if conditions are above or below average for development....its at my web site under the tab......TROPICAL PREDICTION ANALYSIS

Link
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Well TS, my avatar has changed this year. It used to be my nice little rainbow LOL. A bit of a change huh?
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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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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.