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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a good attorney or a not so good one would tear you up in court with statements like these
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I assume you are aware there is really no such thing as "Criteria" to be meet to be declared an Invest?

I would assume that someone must have a definition of the criteria... but I have never been able to find one.. I know.. I have looked around for one a lot.
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Hey guys I wanted to pop back in and thank you for a wonderful little chuckle before going to bed (and an excuse to eat more carbs! I'm going to have to run 5 miles a day this summer to keep up with the carb cravings the blog drama causes :o)

The models are still looking pretty good. Our CATL low has developed some nice symmetrical surface vorticity. I noticed the models are predicting another CATL low as soon as we are done with the current one.
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goodnight everyone! Keep it real and civil! Talk to you all tomorrow!
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AOI
18.5n/77.8w
Member Since: July 15, 2006 Posts: 171 Comments: 53846
Quoting TheCaneWhisperer:


You don't think there are guidelines to follow for declaring an invest and millions of dollars? Common sense my friend and I did state In My Opinion.


I wasn't picking on you :)
I was just trying to point out there is no real criteria... I would assume that someone must have a definition of the criteria... but I have never been able to find one.. I know.. I have looked around for one a lot.

The declaration of an Invest is not a large financial decision.. the next step after that is.

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some geniuses, especially the self proclaimed ones, lack much common sense
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well maybe within 24 hours the "PUBLISHED CRITERIA" will be such tht it can be designated TD1
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Quoting Orcasystems:


Bingo.. so there is no real Criteria


You don't think there are guidelines to follow for declaring an invest and millions of dollars? Common sense my friend and I did state In My Opinion.
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Quoting TheCaneWhisperer:


Personal Criteria and common sense that someone at the NHC would use to hit the go button on an invest, to be EXACT.


Bingo.. so there is no real published Criteria
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Quoting Orcasystems:


I assume you are aware there is really no such thing as "Criteria" to be meet to be declared an Invest?

An "Invest" is exactly that.. and area of Interest.

Invest:
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as the Tropical Weather Outlook or the JTWC/TCFA should be consulted for this purpose.


Yes but they're not just going to want to investigate every little thunderstorm on the ocean. So they have their own criteria.
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Quoting Orcasystems:


I assume you are aware there is really no such thing as "Criteria" to be meet to be declared an Invest?

An "Invest" is exactly that.. and area of Interest.

Invest:
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as the Tropical Weather Outlook or the JTWC/TCFA should be consulted for this purpose.


Personal Criteria and common sense that someone at the NHC would use to hit the go button on an invest, to be EXACT.
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orca if i'm not mistaken an invest gets tropical forecast track points but then again i didnt get slapped silly tonite by the smart stick
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Quoting TheCaneWhisperer:


If convection / circulation persists overnight and model support continues, you'll have your invest AM tomorrow. IMO, all criteria have been met to declare an invest.


I assume you are aware there is really no such thing as "Criteria" to be meet to be declared an Invest?

An "Invest" is exactly that.. and area of Interest.

Invest:
A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets (e.g., microwave imagery) and/or running model guidance. Once a system has been designated as an invest, data collection and processing is initiated on a number of government and academic web sites, including the Naval Research Laboratory (NRL) and the University of Wisconsin Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS). The designation of a system as an invest does not correspond to any particular likelihood of development of the system into a tropical cyclone; operational products such as the Tropical Weather Outlook or the JTWC/TCFA should be consulted for this purpose.
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Starting to disrupt the Low Cloud Deck. This may be real folks.
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ok thanks :)
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Quoting extreme236:


I wouldnt be so sure about that mid atlantic system. While they may not be paying tons of attention to it, I'd use Ana from 03 as a reference for it.


If convection / circulation persists overnight and model support continues, you'll have your invest AM tomorrow for the Caribbean AOI. IMO, all criteria have been met to declare an invest.
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VAbeachhurricanes they are zoomed in shots of the AOI's (Areas Of Interest at the moment)i give lat and long in every shot
Member Since: July 15, 2006 Posts: 171 Comments: 53846
that atlantic storm isnt close to being tropical or subtropical... its a regular ocean cold core storm that you can also find in the NW Territorys of Canada.. its nothing and wont be anything.
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Quoting VAbeachhurricanes:
keeper all those images i dont know what im looking at lol could you use a little wider view?


First looked like the big swirl..and the second like the one off cuba


Big Swirl



Swirl south of Cuba
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Quoting extreme236:


I wouldnt be so sure about that mid atlantic system. While they may not be paying tons of attention to it, I'd use Ana from 03 as a reference for it.


Wasn't Ana the first subtropical storm to get a name from the regular list? If so then there's your reason for her getting named. Also some sources say she almost became fully tropical at one point.

Edit- Wikipedia (Ugh use at own risk) says Ana became fully tropical.
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Quoting VAbeachhurricanes:
keeper all those images i dont know what im looking at lol could you use a little wider view?
the last one is a cen shot of the three convective cells around jamaica 18.5n/77.8w are the mark cen loc
Member Since: July 15, 2006 Posts: 171 Comments: 53846
Quoting HurricaneKing:


Mid atlantic low- I'd say should be a subtropical storm soon. Will they name it? Probably not. If it was during the season they would. This early in the year they would be called out for overly naming things.

Caribbean convection- I think will be an invest by either late tomorrow or early Monday. It's been there for a while and all the models eventually develop it.


I wouldnt be so sure about that mid atlantic system. While they may not be paying tons of attention to it, I'd use Ana from 03 as a reference for it.
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Quoting extreme236:


I'm not too sure to be honest.


:(
OH well.. I actually think its going to be in the next few days..or not until June.
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Quoting extreme236:


I'd be weary getting too ahead of ourselves on the Cuban disturbance...at least until tomorrow. Ive seen countless disturbances look good then fizzle the next day. If I see it hold up decently overnight and the models continue to show development, I'd give it more credit. Mid atlantic low still a bit more interesting to me at the moment.


Mid atlantic low- I'd say should be a subtropical storm soon. Will they name it? Probably not. If it was during the season they would. This early in the year they would be called out for overly naming things.

Caribbean convection- I think will be an invest by either late tomorrow or early Monday. It's been there for a while and all the models eventually develop it.
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Anyways, off the the night...will be back tomorrow to check on these disturbances.
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Quoting Orcasystems:


How does my May 21st date look?
pretty good big fish
Member Since: July 15, 2006 Posts: 171 Comments: 53846
keeper all those images i dont know what im looking at lol could you use a little wider view?
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Quoting Orcasystems:


How does my May 21st date look?


I'm not too sure to be honest.
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AOI
18.5N/77.8W
Member Since: July 15, 2006 Posts: 171 Comments: 53846
orca relevance factor in my world= 0 as do all rude peeps
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Quoting extreme236:


I'd be weary getting too ahead of ourselves on the Cuban disturbance...at least until tomorrow. Ive seen countless disturbances look good then fizzle the next day. If I see it hold up decently overnight and the models continue to show development, I'd give it more credit. Mid atlantic low still a bit more interesting to me at the moment.


How does my May 21st date look?
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Quoting HurricaneKing:
Right now we have a storm that's close to being a subtropical storm and a storm that's close to being called an invest. What month is this?


I'd be weary getting too ahead of ourselves on the Cuban disturbance...at least until tomorrow. Ive seen countless disturbances look good then fizzle the next day. If I see it hold up decently overnight and the models continue to show development, I'd give it more credit. Mid atlantic low still a bit more interesting to me at the moment.
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Quoting extreme236:


Nope



rates
Member Since: May 21, 2006 Posts: 5091 Comments: 115131
Quoting HurricaneKing:
Right now we have a storm that's close to being a subtropical storm and a storm that's close to being called an invest. What month is this?


I think its May,
I might be wrong though.
Member Since: September 7, 2008 Posts: 17 Comments: 1604


AOI
31N/53W
Member Since: July 15, 2006 Posts: 171 Comments: 53846
Quoting HurricaneKing:
Right now we have a storm that's close to being a subtropical storm and a storm that's close to being called an invest. What month is this?



Nothing is allowed to be named until the 21st
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Sleep tight jfv,
See ya tommorow.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Quoting aAnd one more, whatcaster...he whom type a question mark every other post, normally paired with a sir or b


LOL lmao
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Quoting K8eCane:
Orca
only BS you missed is where the who might be who lives


We already know where he lives.... or the real one anyway... relevance factor..."0"
Any weather news on the big swirl in the Atlantic.. or the one south of Cuba
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Right now we have a storm that's close to being a subtropical storm and a storm that's close to being called an invest. What month is this?
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846. beell
As a follow up to earlier posts using the latest GFS:

Both frames from 00Z 05/17 GFS 850mb

After the passage of the cold front, high pressure builds in north of the system-closing the trough to the north and adding a westerly component to steering.

Subject to change/other opinions. Night all. Will have to dream on it for now!

Valid Tuesday/18Z
Photobucket

Valid Thursday/00Z
High pressure to the north continues to slide E or NE as a lee trough develops over the Plains States.

Photobucket
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Evening Ladies and Gentleman! After 6 hours of basketball it is now time to relax and do some blogging on the Underground...lol

Feels weird that I haven't been on much today... like I am kinda out of the loop.

I don't think there is a chance of the Cuban low to become a TD until MAYBE Mon/Tues... that's a big IF on the conditions...

Let's hear it folks!
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Orca
only BS you missed is where the who might be who lives
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Quoting K8eCane:
Hey Taz!
you forgot westcaster


And one more, whatcaster...he whom type a question mark every other post, normally paired with a sir or bud.

Whatcaster...
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Quoting Tazmanian:



do you ues yahoo IM??? 236??


Nope
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Member Since: July 15, 2006 Posts: 171 Comments: 53846
Quoting extreme236:
I'd still watch the system east of Bermuda. Looks to be a bit more convective activity near the center than earlier today.



do you ues yahoo IM??? 236??
Member Since: May 21, 2006 Posts: 5091 Comments: 115131
Quoting HurricaneKing:
What happened to the english language?


The 00z (Midnight run) and 12z (afternoon run) of the computer models are normally the best. They have the most data from more sources incorporated into them.


Very few upper air obs (except along major commercial flight tracks) are available to go into 06 and 18 UTC model runs. Only when there are steering questions for a developed system or a severe threat do the WFOs launch at 06 and 18.
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good night jfv
Member Since: July 15, 2006 Posts: 171 Comments: 53846
Quoting SevereHurricane:


I speak it and type it. :D


I guess that makes 2 of us.
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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.

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