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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Quoting WeatherStudent:


It's not all about the convection, buddy.


If the convection dissipates then whats keeping it from being destroyed by shear? Keep in mind its just a Mid-level circulation.
Member Since: June 9, 2007 Posts: 4 Comments: 15891
Quoting CaneAddict:
Hey everyone..good evening..456 and Drakoen need to cut it out. Anyways I see we now have a disturbance to watch...however it looks awful right now.


If they didn't stop, there would be no disturbance. It's the only one that needs watching at the moment. ;-)
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Quoting nishinigami:
I was wondering how they come up with the names for the invest? I have seen people say 90L 91L. Just curious why those numbers?


From what I've seen, each season they use 90L-99L for investigations. When the pass 99, they go back to 90, even in the same season. I'm not positive about what the L stands for, but it seems to be to signify the North Atlantic basin, as the NHC assigns a different letter to the Pacific basin they cover. Depressions are numbered in the order they occur. For instance, in 2005, I remember there being a Subtropical Depression #23 causing us weather here on the Jersey Shore. The numbers even got higher, as they had to use the Greek alphabet that year.
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wow I have 2 keep track of this system since i live in South FL though it may not become tropical storm Ana.
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1052. IKE
18Z GFS @ 174 hours...landfall finally after dumping 3-4 days worth of rain on SW AL. and the western Florida panhandle....storms ARE more likely to do that early in the season. This one could be a major flooding issue, if that verifies....



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Quoting WeatherStudent:


It's not all about the convection, buddy.



all yes sir it is if you dont have convection then you dont have any thing worth too talk about
Member Since: May 21, 2006 Posts: 5091 Comments: 115125
Rembering last year , expect the unexpected right ?

wasn't that the truth!!!
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1049. Walshy
Quoting Drakoen:
I'm surprised the StSimmons wants to take W456's side, considering I always had his back. I guess when it comes down to it you find out who people really are.


Ill be your friend.
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Hey everyone..good evening..456 and Drakoen need to cut it out. Anyways I see we now have a disturbance to watch...however it looks awful right now.
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Rembering last year , expect the unexpected right ?
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1045. Drakoen
I'm surprised the StSimmons wants to take W456's side, considering I always had his back. I guess when it comes down to it you find out who people really are.

Next time Moonlightcowboy or vortfix has anything against you, you have one person less defending you.
Member Since: October 28, 2006 Posts: 57 Comments: 30494
1040. IKE
Quoting WPBHurricane05:
Its 6pm, you know what that means...Downcast time!!! 12 hours from now people will be talking about how this will likely become the next tropical storm.

Convection waxes and wanes, its part of the diurnal cycle people. When the sun goes down and the earth cools off, cloud tops will be colder.


Exactly...it's like this every year, EVERY system.

Folks should just copy and paste it.
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1039. KEEPEROFTHEGATE (Mod)
Quoting Drakoen:
If it keeps this up there won't be much but a mid-level cloud swirl:
yep going going
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for any gulfcoast surfer that GFS looks very good for the next upcoming swell....
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Quoting kingzfan104:
also, is this looking like it will develop or just be rain

If it will make you happy, after every invest forms I'll send you my probabilities for:
1. Chance of hitting South Florida as a major hurricane
2. Will the schools be closed on Tuesday
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1035. IKE
Quoting atmoaggie:

Last 7 days' rainfall estimate. Maybe 0.5" up here. And 1.5" all around me.



I'm 70 miles east of Pensacola. I've gotten around 3 inches this week...some on Tuesday, Thursday and plenty today.
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Quoting IKE:


FIREFOX is better then IE. I never use IE anymore.



i got firfox 3.5 beta 4 and talk about fast
Member Since: May 21, 2006 Posts: 5091 Comments: 115125
1033. Drakoen
If it keeps this up there won't be much but a mid-level cloud swirl:
Member Since: October 28, 2006 Posts: 57 Comments: 30494
Quoting weatherwatcher12:
Buoys all around the blob are reporting dropping pressures


But not really any different than any other day at about this time. But it is trending down.

Pressure in green (grabbed the wrong buoy a moment ago)


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yeah it is so sparce you could either get bombed or get nothing at all
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Its 6pm, you know what that means...Downcast time!!! 12 hours from now people will be talking about how this will likely become the next tropical storm.

Convection waxes and wanes, its part of the diurnal cycle people. When the sun goes down and the earth cools off, cloud tops will be colder.
Member Since: July 31, 2006 Posts: 56 Comments: 8112
1028. IKE
GFS keeps the low south of the Florida panhandle and SW AL. at least 2 1/2 days.
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Quoting kingzfan104:
so theres is a very little chane of hitting se florida?



too early to tell
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Last 7 days' rainfall estimate. Maybe 0.5" up here. And 1.5" all around me.

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1023. IKE
Quoting acCane08:
Florida can still get plenty of rain from this system!! NWS TPA even mentioned it in their last discussion...

.SHORT TERM (TONIGHT - TUESDAY)...GFS IS AGAIN CHANGING SCENARIOS
REGARDING THE TRACK OF THE POTENTIAL C/OFF LOW LATE MONDAY AND INTO
TUESDAY SENDING IT FURTHER TO OUR EAST AND AROUND THE U/L LOW. ETA
INSISTS IN KEEPING IT TO OUR WEST AND VERY MUCH VERTICALLY STACKED
WITH THE U/L LOW. ETA AND ECMWF ARE ALSO DELAYING THE ARRIVAL OF THE
LOW SOME 6 TO 12 HOURS COMPARED TO GFS. EITHER SCENARIO WILL
DEFINITELY HELP IN ENHANCING DEEP LAYER MOISTURE AND ATMOSPHERIC
INSTABILITY FOR THE NEXT COUPLE OF DAYS SINCE THE STALLING FRONT
JUST TO OUR NORTH WILL NOT ALLOW FOR THE LOW TO DEPART FROM THE
REGION UNTIL AFTER THE SHORT TERM. POPS OF 60 PERCENT MONDAY
AFTERNOON ARE IN PLACE AND WILL BE INCREASED TO 70 PERCENT FROM THE
TAMPA BAY AREA AND SOUTHWARD FOR TUESDAY IN RESPONSE TO THE ARRIVAL
OF THE AFOREMENTIONED FEATURES.


True.

I was speaking of Miami, Keys...areas down that way.
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Quoting Twinkster:
it looks as if the large low in the northwest atlantic is having a huge effect on the short term track of this system

http://www.ssd.noaa.gov/goes/east/nwatl/loop-wv.html


Yes it sure does seem to be attached, even thousands of miles away. All the computer models I saw eventually bring it over Florida.
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1021. Drakoen
Quoting kingzfan104:
so theres is a very little chane of hitting se florida?


No one knows yet. This thing doesn't even have an LLC. Right now its a wait and see.
Member Since: October 28, 2006 Posts: 57 Comments: 30494
1005.
Its a cutoff low...forming along the stalled out front =)
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Buoys all around the blob are reporting dropping pressures
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also, is this looking like it will develop or just be rain
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1017. IKE
Quoting Ossqss:


I loaded FF yesterday and the blog stretch problem mysteriously vanished. I like it so far.


FIREFOX is better then IE. I never use IE anymore.
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Well if the disturbance doesnt regain convection tonight it looks like it the end of the line...
Member Since: June 9, 2007 Posts: 4 Comments: 15891
Florida can still get plenty of rain from this system!! NWS TPA even mentioned it in their last discussion...

.SHORT TERM (TONIGHT - TUESDAY)...GFS IS AGAIN CHANGING SCENARIOS
REGARDING THE TRACK OF THE POTENTIAL C/OFF LOW LATE MONDAY AND INTO
TUESDAY SENDING IT FURTHER TO OUR EAST AND AROUND THE U/L LOW. ETA
INSISTS IN KEEPING IT TO OUR WEST AND VERY MUCH VERTICALLY STACKED
WITH THE U/L LOW. ETA AND ECMWF ARE ALSO DELAYING THE ARRIVAL OF THE
LOW SOME 6 TO 12 HOURS COMPARED TO GFS. EITHER SCENARIO WILL
DEFINITELY HELP IN ENHANCING DEEP LAYER MOISTURE AND ATMOSPHERIC
INSTABILITY FOR THE NEXT COUPLE OF DAYS SINCE THE STALLING FRONT
JUST TO OUR NORTH WILL NOT ALLOW FOR THE LOW TO DEPART FROM THE
REGION UNTIL AFTER THE SHORT TERM. POPS OF 60 PERCENT MONDAY
AFTERNOON ARE IN PLACE AND WILL BE INCREASED TO 70 PERCENT FROM THE
TAMPA BAY AREA AND SOUTHWARD FOR TUESDAY IN RESPONSE TO THE ARRIVAL
OF THE AFOREMENTIONED FEATURES.
Member Since: Posts: Comments:
1014. IKE
Quoting DaytonaBeachWatcher:
Jeez...you two...please...enough.

lol ya think?
this happens every year and this year i have read a lot of stuff from people talking about other people doing those things and then they turn right around and do it themselves.
WEATHER PEOPLE WEATHER, that is what we are all here for, at least most of us.


This blog is tough to take at times.
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so theres is a very little chane of hitting se florida?
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1012. Ossqss
Quoting atmoaggie:


Odd how most software not written by Micro$H!T works that way.


I loaded FF yesterday and the blog stretch problem mysteriously vanished. I like it so far.
Member Since: June 12, 2005 Posts: 6 Comments: 8186

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Quoting atmoaggie:


Odd how most software not written by Micro$#!T works that way.


I cant stand IE! Or Windows for that matter.

Im running a Mac with Bootcamp. I love it...
Member Since: June 9, 2007 Posts: 4 Comments: 15891

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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.