Gathering extratropical storm set to drench Florida, Cuba, and the Bahamas

By: Dr. Jeff Masters , 3:11 PM GMT on May 17, 2009

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A concentrated area of heavy thunderstorms has developed near Jamaica and eastern Cuba, in association with a mid- to upper-level trough of low pressure. The latest 00Z and 06Z runs of the GFS, UKMET, NOGAPS, and ECMWF global dynamical computer models continue to forecast that this disturbance will develop into an extratropical low by Tuesday. The low should bring heavy rain and possible flooding problems to Cuba, Florida, and the Bahamas this week as it lifts northwestward over Florida. Up to eight inches of rain may fall over Florida by Friday (Figure 2), thanks also to a cold front expected to move over the state over the next two days. At present, it appears wind shear will be too high to allow the extratropical storm developing over Cuba to transition into a subtropical or tropical storm. However, if the center emerges into the northern Gulf of Mexico late this week, wind shear may be low enough to allow a transition to a subtropical storm (10% chance).


Figure 1. Latest IR satellite image of the Atlantic, showing the gathering extratropical storm near the eastern tip of Cuba, and the cut-off low spinning in the mid-Atlantic.


Figure 2. Forecast precipitation amount between 8am EDT Sunday 5/17/09 and 8am EDT Friday 5/22/09. Image credit: NOAA/HPC.

There has been little change to the large upper-level cold low spinning in the mid-Atlantic a few hundred miles east of Bermuda. The low 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.

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 Monday.

Jeff Masters

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Surface trough right along the area convection.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting canesrule1:
What "WU"


Weather Underground.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting hahaguy:


WunderGround
where does it say image in wunderground??
Quoting KEEPEROFTHEGATE:
LOOOOK!! A pin-hole eye!!!!
LOL jk jk
Member Since: July 15, 2006 Posts: 163 Comments: 52257
Quoting canesrule1:
What "WU"


WunderGround
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Quoting Stormchaser2007:


Get the image URL and then press "Image" in WU and then pasted the image URL in that box.
What "WU"
Quoting Stormchaser2007:


Here you go


Thanks
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Quoting canesrule1:
I dont know how to post an image, HELP ME PLEASE!!!


Get the image URL and then press "Image" in WU and then paste the image URL in that box.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting hahaguy:
Stormchaser, Can I get a link to that radar site mine got deleted from my bookmarks.


Here you go
Member Since: June 9, 2007 Posts: 4 Comments: 15718
748. IKE
18Z NAM @ 84 hours...

Member Since: June 9, 2005 Posts: 23 Comments: 37858
I dont know how to post an image, HELP ME PLEASE!!!
Conditions at 42058 as of
1950 GMT on 05/17/2009:
Wind Direction (WDIR): ENE ( 60 deg true )
Wind Speed (WSPD): 7.0 m/s
Wind Gust (GST): 8.0 m/s
Wave Height (WVHT): 2.0 m
Dominant Wave Period (DPD): 8 sec
Average Period (APD): 5.9 sec
Mean Wave Direction (MWD): E ( 82 deg true )
Atmospheric Pressure (PRES): 1009.4 mb
Pressure Tendency (PTDY): -1.8 mb ( Falling )
Air Temperature (ATMP): 27.9 °C
Water Temperature (WTMP): 27.4 °C
Dew Point (DEWP): 23.6 °C
Heat Index (HEAT): 31.5 °C
Member Since: Posts: Comments:
Quoting hurricanealley:
Why do some of the model have it forming over cuba

I'm not an expert, but the models are based on developing low pressure systems. This system is not low pressure. The convection would need to couple with a low pressure system and LLC to be what the models are forecasting.
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src=http://www.ssd.noaa.gov/goes/flt/t1/loop-rb.html
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Stormchaser, Can I get a link to that radar site mine got deleted from my bookmarks.
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Negril Point, Jamaica

80.4 °F
Mostly Cloudy
Humidity: 74%
Dew Point: 71 °F
Wind: 5.0 mph from the NNW

Wind Gust: 19.0 mph
Pressure: 29.79 in (Falling Rapidly)
Heat Index: 84 °F
Visibility: 6.2 miles
UV: 6 out of 16
Clouds:
Few 2200 ft
Scattered Clouds 10000 ft
Mostly Cloudy 22000 ft
(Above Ground Level)
Elevation: 30 ft
The NHC has moved the surface trough axis to the east right inline with the convection:
Member Since: October 28, 2006 Posts: 57 Comments: 29714
738. beell
Looking a little windy over the top of our area of interest. The 200mb chart from today's 12GFS indicates the general position of the upper trough just west of the convection. The SW winds across the top may in fact be stronger.
SSD Floater1

Photobucket
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Kingston, Jamaica


82 °F
Mostly Cloudy
Humidity: 62%
Dew Point: 68 °F
Wind: 4 mph from the SE

Pressure: 29.83 in (Falling Rapidly)
Heat Index: 85 °F
Visibility: 6.2 miles
UV: 6 out of 16
Clouds:
Few 1800 ft
Mostly Cloudy 20000 ft
(Above Ground Level)
Elevation: 30 ft
Why do some of the model have it forming over cuba
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Quoting StSimonsIslandGAGuy:
At any rate, the system is seriously decoupled, the lowest pressure in Jamaica is at Negril point on the west end of the island. 29.79" So any surface low is far away from the convection.

Hey StSimons, it is away from the convection. There is also low level vorticity developing east of the convection over Cuba.
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Interesting comma shape.

Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting StSimonsIslandGAGuy:
Drakoen what do you think the lowest pressure the Caribbean system will ever get down to?


too early to tell.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Port-Au-Prince, Haiti


86 °F
Mostly Cloudy
Humidity: 70%
Dew Point: 75 °F
Wind: 16 mph from the SSE

Pressure: 29.89 in (Steady)
Heat Index: 95 °F
Visibility: 6.2 miles
UV: 5 out of 16
Clouds:
Few 1400 ft
Few 1500 ft
Mostly Cloudy 30000 ft
(Above Ground Level)
Elevation: 10 ft
Quoting CybrTeddy:


Can't be that much of a wannabe invest if the NHC's floaters are calling it an invest. Also if cloud tops were Cooling it would be getting stronger, its vice versa right now. We've endured the no LLC thrice last year, Dolly, Fay, Kyle, all tormenting.


The NHC have not declared this an invest. The SSD is just monitoring it as an invest.
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in Guantanamo bay winds are at 6mph from the east
Quoting billy305:
Like Pre-Fay. I remember thinking it was a tropical storm the way it looked, and yet It wasn't a TD.


I remember on TWC they said that pre-Fay looked better than most hurricanes LOL!

Also,
the invest looks like it's losing some convection, but everyone is saying that it's getting better physically.

I say 60% chance of a TD or STD forming from this.
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Okay I'm going to coorect myself. It is not an anti-cyclone. Can anyone tell me if the set-up over Cuba has a particular name? Link
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I read this morning that a closed low may form in the eastern Gulf at the tail end of the cold front later this week. Has anyone heard anything about it? Nice chest high waves with an off shore wind is what I am hoping for here in P'cola.
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Quoting jeffs713:
The wannabe invest has convection popping back on the ESE side, but it looks to be losing convection in the big blob to the north (cloud tops are cooling). Also, it is hardly wrapped around, and I don't see a very strong circulation at any level (the MLC is weak). Check back in tomorrow... it looks uneventful today.


Can't be that much of a wannabe invest if the NHC's floaters are calling it an invest. Also if cloud tops were Cooling it would be getting stronger, its vice versa right now. We've endured the no LLC thrice last year, Dolly, Fay, Kyle, all tormenting.
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Quoting canesrule1:
wow!
almost 1009 millibars
Quoting Stormchaser2007:
Morant,Bay at 29.83" and falling
wow!
Morant Bay, Jamaica at 29.83" and falling
Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting Vortex95:
imo the way the disturbance looks gives the illusion of a few features seen of a TD. Happens on occation.


Also like pre-Dolly.
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Quoting Vortex95:
imo the way the disturbance looks gives the illusion of a few features seen of a TD. Happens on occation.
Like Pre-Fay. I remember thinking it was a tropical storm the way it looked, and yet It wasn't a TD.
Cybr, is that anti-cyclone too low? Shouldn't it be higher? which shear forecast do you prefer?
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pressure in Guantanamo Bay, Cuba is at 29.89 inches or 1012 millibars and steady
window shear has drop too 20kt

Member Since: May 21, 2006 Posts: 5089 Comments: 114051
The wannabe invest has convection popping back on the ESE side, but it looks to be losing convection in the big blob to the north (cloud tops are cooling). Also, it is hardly wrapped around, and I don't see a very strong circulation at any level (the MLC is weak). Check back in tomorrow... it looks uneventful today.
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Upper Level Divergence:


Lower Level Convergence:
Member Since: June 9, 2007 Posts: 4 Comments: 15718

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.