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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yeah not a good sign
Member Since: July 15, 2006 Posts: 170 Comments: 53514
Quoting KEEPEROFTHEGATE:
well taz i believe if it makes it over night then rebuilds during the day tomorrow sometime after 4 pm sunday afternoon we may have 90l the first of many there may even be a 91l as well if the mids atlantic swirl does anything


I can hardly believe it's beginning
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AOI
33N/53W

Member Since: July 15, 2006 Posts: 170 Comments: 53514
AOI
19N/79W
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682. beell
676. and El Nino in July.

The trend in the SOI on a weekly basis sure seems to be climbing!
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681. Skyepony (Mod)
Just caught a good quikscat on the midatlantic blob.. tightning up nicely with the winds coming toward the center.




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well taz i believe if it makes it over night then rebuilds during the day tomorrow sometime after 4 pm sunday afternoon we may have 90l the first of many there may even be a 91l as well if the mids atlantic swirl does anything
Member Since: July 15, 2006 Posts: 170 Comments: 53514
Quoting SevereHurricane:

Within the next 24hrs.



cool i can start my 1st round
Member Since: May 21, 2006 Posts: 5091 Comments: 114919
Quoting Tazmanian:
when do you think will see 90L???

Within the next 24hrs.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
when do you think will see 90L???
Member Since: May 21, 2006 Posts: 5091 Comments: 114919
Quoting Weather456:


2009 Hurricane Season Forecast

2009 Hurricane Season FAQ


Rumor is ECMWF is only forecasting 8 named storms this year and El Nino in July.
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RAMSDIS Loop The circulation is pretty much stationary.
Member Since: October 28, 2006 Posts: 57 Comments: 30150
AOI
MARK
19N/79W

Member Since: July 15, 2006 Posts: 170 Comments: 53514
672. beell
10cm = 3.9in
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Quoting Weather456:
Something interesting to note...If subtropical storm Ana do form, it would be the second time that a the name Ana was used for a subtropical storm before the season begins. The other was breifly subtropical storm Ana in 2003.


Just like how Bertha 2008 surpased Bertha 1996.
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NAM 00z will be running soon...
Member Since: October 28, 2006 Posts: 57 Comments: 30150
Heavy rain and lightning in Palm Harbor Fl right now. Back on the blog!
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Well..... Here we go again! Just been lurking along, reading and clicking on all the links. I sure do hope that the models will hold the line and give us some rain here in south Fl. Kudos to all the ole' regulars that keep this blog relevant, great reading! I hope we are ALL ready for the season.....
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Quoting stormhank:
anyone got any guesses on how active this season will be and the strength of bermuda high? fla / gom storms or east coast // fish storms??


2009 Hurricane Season Forecast

2009 Hurricane Season FAQ
Member Since: July 24, 2005 Posts: 407 Comments: 19076
its way too soon too tell where the bermuda high wil set up shop trying asking that when it comes later in july


how evere i did here some one said that the bermuda high is at all most the same set up this year that was in when it was 2004
Member Since: May 21, 2006 Posts: 5091 Comments: 114919
Quoting WPBHurricane05:


What unit of measure would that be?


Probably in mm or cm
Member Since: October 28, 2006 Posts: 57 Comments: 30150
Quoting Drakoen:
ECMWF rainfall for panhandle
ECMWF rainfall for South Florida


What unit of measure would that be?
Member Since: July 31, 2006 Posts: 56 Comments: 8112
anyone got any guesses on how active this season will be and the strength of bermuda high? fla / gom storms or east coast // fish storms??
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Area forecast discussion
National Weather Service New Orleans la
320 PM CDT Sat may 16 2009


Long term...
on the other hand the long term weather will be dominated by
large scale conditions. A cold front is approaching the Arklatex
region this evening. This cold front and its associated upper
level through will move from Oklahoma and Texas to the Gulf
coastal area late tonight and then slowly into the Louisiana and
Mississippi coastal waters Sunday and Sunday night. The sky will
clear and cooler temperatures be the rule Monday and Tuesday with
lows falling into 50s at night and in the upper 70s to around 80.


Beyond Tuesday...long range models show part of the upper level
trough associated with the cold front getting cut off in the
southeast Gulf. It is possible that the cut off low could merge
with a weak upper level low pressure system that is expected to
drift northwest from the Caribbean later this week. Any potential
development of a surface low associated with this upper level
system will be slow to occur. Confidence is not high at this time.
We will continue to watch this situation carefully. The only
change made to the long range grids was to bring in more clouds
associated with the upper low which most models move towards the
northern Gulf Coast late this week. Otherwise have not made any
changes to the long range chance of rain and weather grids.
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting dearmas:


Well here in Rivewview Florida we have had nothing but rain since Tuesday :) and looks like more to come all this week


cool.. send some of that north to pasco. cause my sprinkler pump is out of whack and I can't stay up till midnight and water on my day!!
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The Atlantic Ridge seems to be the mean Steerage thru time.
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Recent new discussion from the NHC

Link
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good day too you sir
Member Since: May 21, 2006 Posts: 5091 Comments: 114919
ECMWF rainfall for panhandle
ECMWF rainfall for South Florida
Member Since: October 28, 2006 Posts: 57 Comments: 30150
Quoting hurricanehanna:


Don't forget the Zapps...that's another necessity!


I love Zapp's.
Best in the world.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Zapps Potato Chips.

I like the Jalapeno ones.

They have Character..
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting stormhank:
Im no expert by no means but, I thought what ever formed was gonna do so after the front comin down across SE US passed down into GOM?


This system is farther south and east. The previous runs were taking this system from the Yucatan channel. Now they are saying south of Cuba.
Member Since: October 28, 2006 Posts: 57 Comments: 30150
Quoting Patrap:
I may have to add that to my Prep List on me Blog..LOL


Don't forget the Zapps...that's another necessity!
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651. beell
Quoting Drakoen:


I'm thinking more along the lines of the 18z runs since the system is being instigated further south and east than the previous runs. It should move north as the prefrontal trough advects southward. This should allow the system to come over or adjacent to South Florida before entering the GOM. Intensification here is questionable as the system becomes better stacked with a large-scale 500mb low and a negatively tilted upper trough axis. Either way we're looking at totals between 3-5 inches.


And then we watch it mill around onshore-waiting to get picked up by the next trough over the CONUS. And the rain-inducing interaction with its attendant cold-front.
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Looks like tonight's descending quicksat pass will catch the area. At most we can look for is a surface trough.
Member Since: October 28, 2006 Posts: 57 Comments: 30150
I may have to add that to my Prep List on me Blog..LOL
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Im no expert by no means but, I thought what ever formed was gonna do so after the front comin down across SE US passed down into GOM?
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Quoting Patrap:
Excellent Choice.. ummmm Abita,


Why thank you. I never start Hurricane season without it!
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Quoting cchsweatherman:


Thats most likely due to the fact that this remains mainly a mid-level system at the moment. Once it gains some surface reflection tomorrow, we should see the wind speeds increase.


yea I know
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Excellent Choice.. ummmm Abita,
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting Patrap:

CONUS front on the Move,the other Player comes on down.

Did he leave you a Cold one as he passed Hhanna..?

No, had to grab an Abita Strawberry myself (luckily the fridge is only 5 feet away!)
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Quoting RMM34667:


yeah all of FL except tampa bay. we got next to nothing from fay!


Well here in Rivewview Florida we have had nothing but rain since Tuesday :) and looks like more to come all this week
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And according to where the storm develops, if it does and tracks, the landmasses of Cuba and Florida are other factors.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
CONUS front on the Move,the other Player comes on down.

Did he leave you a Cold one as he passed hhanna..?
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting Weather456:
Not much under the bands of thunderstorms but a few knots higher the surrounding trades.



Thats most likely due to the fact that this remains mainly a mid-level system at the moment. Once it gains some surface reflection tomorrow, we should see the wind speeds increase.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
My husband just passed by the computer and said, oh no...it's the THE BLOG ...time for a beer!
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One thing I've notice, is that the advancing upper trough over the Central CONUS is critical to the cyclogensis of this feature. As dips across the area, the base becomes cut-off and secluded advecting PV into the region (which is needed for vorticity). Also it helps to split the jet causing a good size region of low wind shear.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
RMM..that's what I'm worried about. Tampa always misses out on the good stuff lol.
Member Since: August 29, 2006 Posts: 0 Comments: 843

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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.