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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From MLB Discussion:
A cold front will move southward into northern
Florida tonight and approach the north end of the County Warning Area late
overnight so will keep a chance for showers over Northern Lake and
Volusia counties.

So should be in North Central FL by tomorrow morning.
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Quoting Drakoen:
The front is advancing:


Yep. 65F in Slidell 30 minutes ago. 81 at same time yesterday.

Windows open, air off. 52 tonight. A LOT more excited about 3 nights in the 50s than I am about this pseudo-invest.
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Quoting GeoffreyWPB:
How far south is that front forecast to dip into Fla.?


idk but I live in lake worth and national weather service and the weather channel still show an 80% chance of rain i have no idea where you got your information that now only says 10%
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1256. 11117
Bring on the Rain?
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Quoting Drakoen:
LOL

Sorry Drak's graphic from post 1212 didn't copy. But there is convection building over the more northern part of Cuba. The LLC I was referring to is under this convection. Looking at this on Dvorak imagery it seems that this small area of convection is separate from the larger mid-level area of interest we are watching. Isn't this also closer to areas where pressure is dropping?
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Im liking my forecast...

WPB's forecast for next week.

Member Since: June 9, 2007 Posts: 4 Comments: 15718
1253. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 29714
So far the fronts showing no sighs of slowing down
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1250. Drakoen
Quoting weatherwatcher12:

was the front forecast to advance


Yes.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1249. IKE
Quoting Drakoen:
The front is advancing:


It's already through Tallahassee,FL.

Mostly Cloudy

73 °F
(23 °C)
Humidity: 90 %
Wind Speed: N 3 MPH
Barometer: 29.96" (1014.5 mb)
Dewpoint: 70 °F (21 °C)
Visibility: 10.00 mi.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting WeatherStudent:
Enough said there, Ikster, enough said.


Ikster? That sounds familiar from last year.
Member Since: June 9, 2007 Posts: 4 Comments: 15718
Quoting Drakoen:


If you're not JFV then I have 3 heads.




now that was funny
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Quoting Drakoen:
The front is advancing:

was the front forecast to advance
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1244. Drakoen
Quoting WeatherStudent:
Enough said there, Ikster, enough said.


If you're not JFV then I have 3 heads.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1243. IKE
Quoting sporteguy03:


Exactly Ike! Yet we have some here contradicting this and calling for its demise as you say blogger or NHC, I go with NHC.


I haven't seen a model develop it before Monday afternoon/evening and I've followed all of them since this started.

As far as track....???
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1242. Drakoen
The front is advancing:
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1241. dearmas
Quoting Drakoen:
I have an 80% chance of rain for Monday and Tuesday.


Here in Tampa Fl we have 90% for Monday and 70-80% for the rest of the week
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Here comes the rain- Link
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting CybrTeddy:


6 AM is peak D-Max I believe, judging by the last 4 years I've watched them on this blog, this one will most likely do the same and blow up. It did it last night too.

thanks for the info
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WU and TWC also have West Palm at 80%. I was looking at the MSN weather forecasts.
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Gitmo radar- Link
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Quoting weatherwatcher12:

exactly when is D-Max


6 AM is peak D-Max I believe, judging by the last 4 years I've watched them on this blog, this one will most likely do the same and blow up. It did it last night too.
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Quoting IKE:
DURING THE NEXT DAY...A SURFACE LOW IS FORECAST TO DEVELOP ALONG
THE SURFACE TROUGH AND MOVE N OF THE CARIBBEAN MONDAY NIGHT.

........

That's straight from the NHC. It was never forecast to develop today or tonight.


Exactly Ike! Yet we have some here contradicting this and calling for its demise as you say blogger or NHC, I go with NHC.
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Quoting SevereHurricane:


If you aren't JFV then im a grandmaw.


you are definitely not a grandmaw...

Heavy rain here this evening - almost in wierd bands.

ok - have to go keep an eye on the kids for a bit. Teens and b/f don't mix.
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Quoting CaneAddict:
Around the Diurnal Max. is when this sytem should blow up some decent convection...

exactly when is D-Max
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Quoting canesrule1:
a dust storm has more convection than this disturbence, I'm calling it 8:09 pm EST, R.I.P "invest"


Oh you have no idea, this is your first year blogging by the sound of it. If it isn't I haven't seen your face. We've had invests that looked so pathetic it was laughable, Dean, Dolly, Fay, Felix for example. Lots of people wrote off pre-Felix, Pre-Dolly, Pre-Fay during this time, only to say 'OMG TD by afternoon!'.
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How far south is that front forecast to dip into Fla.?
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Around the Diurnal Max. is when this sytem should blow up some decent convection...
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1228. IKE
REPEATING****

DURING THE NEXT DAY...A SURFACE LOW IS FORECAST TO DEVELOP ALONG
THE SURFACE TROUGH AND MOVE N OF THE CARIBBEAN MONDAY NIGHT.

........

That's straight from the NHC. It was never forecast to develop today or tonight.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1227. Drakoen
I have an 80% chance of rain for Monday and Tuesday.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
1225. IKE
DURING THE NEXT DAY...A SURFACE LOW IS FORECAST TO DEVELOP ALONG
THE SURFACE TROUGH AND MOVE N OF THE CARIBBEAN MONDAY NIGHT.

........

That's straight from the NHC. It was never forecast to develop today or tonight.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Drakoen:
LOL


Drak no offense but you know very well its Durinal Mim. Now if it looks like this in the morning my tune will change.

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SJ...it's be nice if you answered your phone...

Drak....

Where's it gonna hit?!?!?!?!?!
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Hey SJ good to see you on here.

Canes,
Why post the TWD seems the NHC disagrees with what you said?
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Quoting canesrule1:
ok, but right now it looks like $#!%

that's usually what happens to tropical waves at D-Min
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Quoting weatherwatcher12:

Right now it's D-min just wait a little till morning then you can call it based on what is there
ok, but right now it looks like $#!%
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1217. Drakoen
GFS 18z Ensemble

Anywhere between Jacksonville and Key West could feel the affects of this system.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
Good to see ya sg03, and well said.

Although I think CDL could be on the right track with the low over Cuba. Seems to be what the 18z GFS hints at as well?
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Quoting canesrule1:
a dust storm has more convection than this disturbence, I'm calling it 8:09 pm EST, R.I.P "invest"

Right now it's D-min just wait a little till morning then you can call it based on what is there
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Dang...this morning our local met was saying heavy rains beginning tomorrow and continuing thru Thursday...Now looking at our forecast, it reads only a 10% chance of rain for the next three days.
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000
AXNT20 KNHC 172312
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN MAY 17 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2245 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE EXTENDS FROM 11N40W TO 1N43W MOVING W NEAR
10 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD INVERTED-V STRUCTURE
IN THE LOW-LEVEL CLOUD COVERAGE...AND IS ASSOCIATED WITH A
MAXIMUM IN DEEP LAYER MOISTURE BASED ON TOTAL PRECIPITABLE WATER
PRODUCT FROM CIMSS. COMPUTER MODEL GUIDANCE INDICATES THAT THE
WAVE COINCIDES WITH AN AREA OF LOW LEVEL CYCLONIC CIRCULATION.
SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 180 NM E OF
THE WAVE S OF 4N.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 7N11W 3N17W CROSSING THE EQUATOR
NEAR 22W EXTENDING TO 2S30W 3S35W AND INTO NE BRAZIL NEAR 3S46W.
SCATTERED MODERATE CONVECTION IS S OF 3N BETWEEN 13W-20W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF 3N BETWEEN
21W-29W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYER TROUGH OVER THE SOUTH CENTRAL CONUS IS ASSOCIATED
WITH A SURFACE STATIONARY FRONT OVER THE W GULF THAT EXTENDS
FROM SOUTH CENTRAL LOUISIANA NEAR 29N91W TO 26N95W TO THE COAST
OF MEXICO NEAR 22N98W. ALSO...A SURFACE TROUGH IS LOCATED TO THE
E OF THE FRONT AND EXTENDS FROM S MISSISSIPPI NEAR 30N89W TO N
OF THE YUCATAN PENINSULA NEAR 22N89W. LOW LEVEL CONVERGENCE NEAR
THE SURFACE FRONT AND SURFACE TROUGH IS SUPPORTING SCATTERED
SHOWERS AND ISOLATED THUNDERSTORMS OVER THE GULF N OF 26N
BETWEEN 86W-95W...WITH SCATTERED SHOWERS S OF 23N W OF 91W.
ADDITIONALLY...RELATIVELY UNSTABLE ATMOSPHERIC CONDITIONS
ASSOCIATED WITH MOIST SOUTHEASTERLY FLOW OVER THE E GULF ARE
SUPPORTING SCATTERED SHOWERS AND THUNDERSTORMS FROM 23N TO 29N E
OF 84W INCLUDING THE W FLORIDA PENINSULA...THE FLORIDA
KEYS...THE STRAITS OF FLORIDA...AND W CUBA. ALL OF THE SHOWER
AND THUNDERSTORM ACTIVITY IS BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE BETWEEN THE AFOREMENTIONED DEEP TROUGH AND AN UPPER
LEVEL RIDGE OVER THE SW GULF. THE FRONT IS EXPECTED TO MOVE
SOUTHEASTWARD AS A COLD FRONT THROUGH TUESDAY. ALSO... DURING
THE NEXT DAY...MANY OF THE GLOBAL MODELS ARE SHOWING LOW
PRESSURE DEVELOPING OVER THE N CENTRAL CARIBBEAN...EITHER
EXTRATROPICAL OR SUBTROPICAL...AND MOVING GENERALLY N. THE
DEVELOPMENT AND TRACK OF THE LOW REMAIN UNCERTAIN...THOUGH
COMPUTER MODELS SUGGEST THAT WINDS WILL INCREASE AROUND THE LOW.

CARIBBEAN SEA...
NUMEROUS SHOWERS AND THUNDERSTORMS ARE AFFECTING PORTIONS OF THE
NORTH CENTRAL CARIBBEAN N OF 16N BETWEEN 71W-79W...INCLUDING
JAMAICA...E CUBA...AND W HISPANIOLA. THIS ACTIVITY IS BEING
SUPPORTED BY LOW LEVEL CONVERGENCE NEAR A SURFACE TROUGH THAT
EXTENDS FROM E CUBA NEAR 20N76W TO 16N76W. THE ACTIVITY IS ALSO
BEING SUPPORTED BY UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER RIDGE
OVER THE SW NORTH ATLC AND AN UPPER TROUGH OVER THE S CARIBBEAN.
DURING THE NEXT DAY...A SURFACE LOW IS FORECAST TO DEVELOP ALONG
THE SURFACE TROUGH AND MOVE N OF THE CARIBBEAN MONDAY NIGHT.
UPPER LEVEL DIVERGENCE AND ATMOSPHERIC INSTABILITY ASSOCIATED
WITH THE UPPER TROUGH OVER THE S CARIBBEAN IS ALSO SUPPORTING
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE SW
CARIBBEAN S OF 10N AND SCATTERED SHOWERS OVER THE E CARIBBEAN
FROM 14N TO 17N BETWEEN 63W-69W. ADDITIONALLY...ATMOSPHERIC
INSTABILITY IS RESULTING IN SCATTERED SHOWERS AND THUNDERSTORMS
OVER W CUBA...IMPACTING THE ADJACENT COASTAL WATERS. ALSO...
SCATTERED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF A
SURFACE TROUGH OVER THE NW CARIBBEAN THAT EXTENDS FROM 19N85W TO
16N85W. MEANWHILE...SURFACE HIGH PRESSURE CENTERED W OF BERMUDA
IS MAINTAINING 15-20 KT EASTERLY TRADE WINDS ACROSS MUCH OF THE
E CARIBBEAN.

ATLANTIC OCEAN...
AN OCCLUDED 1006 MB SURFACE LOW IS NEARLY STATIONARY NEAR
32N53W. AN ASSOCIATED SURFACE COLD FRONT EXTENDS FROM 32N46W TO
27N47W TO 24N49W AND CONTINUING SOUTHWESTWARD AS A STATIONARY
FRONT TO 19N56W. FROM 19N56W...THE BOUNDARY WEAKENS TO A SURFACE
TROUGH AND EXTENDS SW TO 16N59W. LOW LEVEL CONVERGENCE IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG
AND WITHIN 300 NM E OF THE SURFACE FRONTS AND SURFACE TROUGH. A
SURFACE TROUGH IS ALSO PRESENT TO THE W OF THE COLD AND
STATIONARY FRONTS AND EXTENDS FROM 30N48W TO 27N52W TO 27N58W.
LOW LEVEL CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 60
NM EITHER SIDE OF THIS SURFACE TROUGH. ALL OF THIS SHOWER AND
THUNDERSTORM ACTIVITY IS BEING ENHANCED BY UPPER LEVEL
DIFFLUENCE NEAR AN UPPER TROUGH THAT EXTENDS FROM AN UPPER LOW
NEAR 32N52W TO 28N49W TO 26N49W. FARTHER TO THE W...A SURFACE
RIDGE EXTENDS SOUTHWESTWARD FROM SURFACE HIGH PRESSURE CENTERED
W OF BERMUDA. SUBSIDENCE ASSOCIATED WITH THIS SURFACE
RIDGE...COMBINED WITH ATMOSPHERIC STABILITY ASSOCIATED WITH AN
UPPER RIDGE OVER THE SW NORTH ATLC...IS SUPPORTING GENERALLY
FAIR WEATHER CONDITIONS ACROSS MUCH OF THE SW NORTH ATLC.
HOWEVER...MOIST SOUTHEASTERLY LOW LEVEL FLOW OVER PORTIONS OF
THE SW NORTH ATLC IS SUPPORTING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS S OF 25N W OF 78W. ADDITIONALLY...NUMEROUS SHOWERS
AND THUNDERSTORMS ASSOCIATED WITH THE SURFACE TROUGH OVER THE
NORTH CENTRAL CARIBBEAN ARE MOVING NORTHWARD INTO THE SW N
ATLC...AFFECTING LOCATIONS S OF 22N BETWEEN 71W-79W...INCLUDING
PORTIONS OF E CUBA AND W HISPANIOLA. DURING THE NEXT DAY...MANY
OF THE GLOBAL MODELS ARE SHOWING LOW PRESSURE DEVELOPING OVER
THE N CENTRAL CARIBBEAN...EITHER EXTRATROPICAL OR SUBTROPICAL...
AND MOVING GENERALLY N INTO THE SW NORTH ATLC. THE PRESSURE
GRADIENT AROUND THE LOW IS FORECAST TO RESULT IN GALE CONDITIONS
N OF 28N W OF 75W MONDAY NIGHT THROUGH WEDNESDAY. ACROSS THE E
ATLC...A SURFACE RIDGE IS PRESENT WHERE MAINLY ZONAL FLOW ALOFT
IS OCCURRING AND FAIR WEATHER CONDITIONS PERSIST. ACROSS THE
TROPICAL ATLC...AN UPPER LEVEL RIDGE IS PRESENT S OF 11N E OF
58W WITH UPPER LEVEL HIGHS CENTERED NEAR 6N46W AND 5N25W. UPPER
LEVEL DIVERGENCE ASSOCIATED WITH THE UPPER LEVEL HIGHS AND UPPER
LEVEL RIDGE IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ
AND WITH THE TROPICAL WAVE THAT EXTENDS FROM 11N40W TO 1N43W.

$$
COHEN
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1212. Drakoen
LOL
Member Since: October 28, 2006 Posts: 57 Comments: 29714
a dust storm has more convection than this disturbence, I'm calling it 8:09 pm EST, R.I.P "invest"
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Evening all

You said it SSIG....Hurry up and wait...

Sure wish we had better buoy coverage in that area...

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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.