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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this be come there is a LCC or not dos not mean we have a TD or TS
Member Since: May 21, 2006 Posts: 5091 Comments: 114765
is it moving true east or ene???
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Quoting CybrTeddy:
Anyone remember this? Lol.
Link
Could use some of that right now.


lol...I tell ya
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Member Since: Posts: Comments:
Anyone remember this? Lol.
Link
Could use some of that right now.
Member Since: July 8, 2005 Posts: 259 Comments: 23619
But you never actually specifield wind-wise on it, 456? By that I meant, numerically speaking, how many ??mph, OK?

Read carefully again:

The tightened pressure gradient between the forecast low and high pressure over the Atlantic implies some possible gale force winds. Please refer to you local weather office.
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The Weather Channel just mentioned a possible low forming south of Florida in the next 48 hours...They said it was only an area of disturbed weather currently....
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Convective bursts are occurring on the south side of the disturbance. Odd I though it would have been losing convection by now.

Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting HurricaneKing:


Nothing in the gulf to worry about at this time. The weak trough that's there is getting plowed over by the front.

yes i also noticed the front... just asking
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Quoting Stormchaser2007:


It is not a TD. It doent have a LLC recognized by the TPC. Heck its not even an invest.


Agreed, although it might be declared if it persists to about 5 PM.
Member Since: July 8, 2005 Posts: 259 Comments: 23619
Quoting WeatherStudent:


It look sheered like a sheep.


It looks better now than it has all day. Less sheared and beginning to get that "trying to work down to the surface" look.
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Quoting canesrule1:
there is an LLC at 76 and 17.5 for sure. we got ourselves our first T.D because there is an LLC


It is not a TD. It doent have a LLC recognized by the TPC. Heck its not even an invest.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting AussieStorm:

ok
could the trough in the northern GOM become something or is the shear to high?


Nothing in the gulf to worry about at this time. The weak trough that's there is getting plowed over by the front.
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Quoting Stormchaser2007:


Do you have a source? You need to cite where you get your information. You cant go around blurting random things out if you dont have some type of source.

my thoughts exactly
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Quoting WeatherStudent:


But you never actually specifield wind-wise on it, 456? By that I meant, numerically speaking, how many ??mph, OK?


What you would typically expect in any Tropical Storm. You will probally get 40 mph wind gusts at worst from this thing. Nothing significant is going to happen. Relax. Its going to primarily be a rainmaker! Period.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting canesrule1:
there is an LLC at 76 and 17.5 for sure. we got ourselves our first T.D because there is an LLC


There was barley even a wind shift associated with it this morning. All it has is a defined MLC, NOTHING is on the surface.
Member Since: July 8, 2005 Posts: 259 Comments: 23619
ONLY the "NHC" can Declare a TD..not a single blogger in a Blog.

The NRL hasnt even declared an invest yet.
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Quoting canesrule1:
It has an LLC.


Do you have a source? You need to cite where you get your information. You cant go around blurting random things out if you dont have some type of source.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting weatherwatcher12:

That's exactly what we are having now lol


Thats as bad as its going to get,
Just some rain. lol
Member Since: September 7, 2008 Posts: 17 Comments: 1604
wouldn't it(jamacian blob) usually get designated a "surface feature",before an invest was started????
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AOI/00/00L
TRACKMARK
17.3N/75.4W
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there is an LLC at 76 and 17.5 for sure. we got ourselves our first T.D because there is an LLC
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Quoting HurricaneKing:


In my opinion.

ok
could the trough in the northern GOM become something or is the shear to high?
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has the quick scat picked up the blob
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting foggymyst:
What potential winds could a STS bring?


Tropical Update 4th paragraph
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<
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Quoting SevereHurricane:


Rainy& A little Breezy

That's exactly what we are having now lol
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting WeatherStudent:


I don't think I am, LOL, :) Thanks, 456.


That's an understatement.
Member Since: October 28, 2006 Posts: 57 Comments: 29927
Quoting canesrule1:
I Think this should be classified as a TD. it has a swirl in the middle of its convection (thats why it has a comma shape)


It doesn't have a llc yet. Any swirl we see is midlevel at the moment.
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It has an LLC.
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Quoting SevereHurricane:


Rainy& A little Breezy

thank you
Member Since: May 16, 2009 Posts: 1 Comments: 1231
<
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I Think this should be classified as a TD. it has a swirl in the middle of its convection (thats why it has a comma shape)
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Quoting Weather456:


It is. But outflow is common in thuderstorms on that scale, and this "outflow" is also working hand-in-hand with the upper level winds north of the system.


Thanks 456, I have not see the likes of that just from convection. I learn something new everyday. L8R -- yard work time :(
Member Since: June 12, 2005 Posts: 6 Comments: 8185
Hi Chicklit - we are girls are chopped liver today - seems we are once again outnumbered by the guys!

Yes, it does look like a lot of rain for Florida, hope it stays that way.
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What potential winds could a STS bring?
Member Since: September 23, 2008 Posts: 0 Comments: 383
Visible loop- Link

Comma shapes in storms- Link
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WeatherStudent,

lol

You are a very enthusiastic young fellow.
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Quoting WeatherStudent:
Thanks Twinster, I appreciate that.


just to give u a word of advice try and not talk as much because you are digging yourself into a bigger hole every time you post.
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Windward passage. Wow my mind is slow today. I couldn't remember the name to save my life. Thanks guys.
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Quoting AussieStorm:

IMO???


In my opinion.
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windward passage
remember systems always try and travel the path of less resistance and that would be a perfect place to move north ward over and avoid the landmass of cuba
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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.