Still watching for a potential early-season Atlantic subtropical storm

By: Dr. Jeff Masters , 7:10 PM GMT on May 16, 2009

Share this Blog
1
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 587 - 537

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

Quoting Weather456:
Here we go. Gotta get the butter for this popcorn.



am with you
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Can we PLEASE not start this AGAIN? Jeeeeeeez!
Member Since: Posts: Comments:
Quoting Littleninjagrl:
WPB...I told you I would send you some! :)


Indeed you did!
Member Since: July 31, 2006 Posts: 56 Comments: 8112
Here we go. Gotta get the butter for this popcorn.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Stormchaser2007:


Im sorry but that sounded exactly like something JFV would say.



was thinking the same thing,sir..lol
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Im sorry but that sounded exactly like something JFV would say.


I wish he would just admit he was JFV.
Member Since: September 7, 2008 Posts: 17 Comments: 1604
Please,.for the Love of The Blog.


Let the Wookie Win.



Member Since: July 3, 2005 Posts: 421 Comments: 127628
Quoting Stormchaser2007:


Im sorry but that sounded exactly like something JFV would say.



i think he is JFV
Member Since: May 21, 2006 Posts: 5091 Comments: 114758


On a different note convection is increasing somewhat.

Member Since: Posts: Comments:
WPB...I told you I would send you some! :)
Member Since: Posts: Comments:
.
Member Since: Posts: Comments:
Woohoo!! Its raining- Link

Member Since: July 31, 2006 Posts: 56 Comments: 8112
572. IKE
Quoting Drakoen:
You can see the mid level rotation on satellite imagery.


I see it too. Nice satellite.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
When will we see the wind shear drop?
Member Since: Posts: Comments:
Quoting Tazmanian:
Link


Good ole, hurricaneturtle
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting WeatherStudent:


Taz, who wrote that very disturbing scenerio concerning our soon to be cyclone?


Taz didn't write that.
Member Since: Posts: Comments:
Quoting Weather456:
Sounds like CCH?


Thats actually not from me. Haven't written up my own discussion yet, but will likely post one tomorrow if the models continue their consensus.
Member Since: Posts: Comments:
Quoting Tazmanian:

The area of disturbed weather in the Atlantic mentioned in the previous discussion continues to be a concern tonight. It has gone further south than originally projected by computer models, and is now a broad area of thunderstorm activity south of Cuba. It is more impressive than before due to decreasing shear, and appears to be coalescing into an organized area of convection. Some shear can still be seen on visible satellite imagery, but 200-850 mb shear is below 30 kt and should decrease further as an anti-cyclone builds above the convection. The GFS is forecasting the disturbance to become a cyclone within 24-48 hours, and the NAM is about the same. The Florida State University phase space analysis still indicates that this will be sub-tropical in nature due to cool upper-levels, but it could end up being a significant cyclone anyways. It will be over the fairly warm waters of the northern Caribbean and Florida Straits/Gulf of Mexico for a few days as it heads northward along the western periphery of the Bermuda high, so a moderate to strong sub-tropical storm is possible. I have outlined this forecast scenario in the graphic below. The biggest story with this system will likely be rain, it appears that it will move slowly across Florida which should cause high rainfall totals. Even if the disturbance doesn't become a cyclone it would still cause alot of rain in Florida. I will continue to monitor this strange pre-season disturbance.


He got it from
http://www.hurricanewarning1.com/
Member Since: September 7, 2008 Posts: 17 Comments: 1604
2009 Hurricane Season Outlook
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Link
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Sounds like CCH?
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Wow. We might have two sub-tropical (or tropical) systems in mid-May!

I give the caribbean system now 40-80% chance of becoming a storm and the CATL system now 30-50%.
Member Since: Posts: Comments:
500 mb Vorticity

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Tazmanian:

The area of disturbed weather in the Atlantic mentioned in the previous discussion continues to be a concern tonight. It has gone further south than originally projected by computer models, and is now a broad area of thunderstorm activity south of Cuba. It is more impressive than before due to decreasing shear, and appears to be coalescing into an organized area of convection. Some shear can still be seen on visible satellite imagery, but 200-850 mb shear is below 30 kt and should decrease further as an anti-cyclone builds above the convection. The GFS is forecasting the disturbance to become a cyclone within 24-48 hours, and the NAM is about the same. The Florida State University phase space analysis still indicates that this will be sub-tropical in nature due to cool upper-levels, but it could end up being a significant cyclone anyways. It will be over the fairly warm waters of the northern Caribbean and Florida Straits/Gulf of Mexico for a few days as it heads northward along the western periphery of the Bermuda high, so a moderate to strong sub-tropical storm is possible. I have outlined this forecast scenario in the graphic below. The biggest story with this system will likely be rain, it appears that it will move slowly across Florida which should cause high rainfall totals. Even if the disturbance doesn't become a cyclone it would still cause alot of rain in Florida. I will continue to monitor this strange pre-season disturbance.

You got a link for that?
Member Since: Posts: Comments:
Quoting Drakoen:

Satellite Imagery from UM
drak iam gonna grab that link nice image on favs now
Member Since: July 15, 2006 Posts: 169 Comments: 53296
Quoting Tazmanian:

The area of disturbed weather in the Atlantic mentioned in the previous discussion continues to be a concern tonight. It has gone further south than originally projected by computer models, and is now a broad area of thunderstorm activity south of Cuba. It is more impressive than before due to decreasing shear, and appears to be coalescing into an organized area of convection. Some shear can still be seen on visible satellite imagery, but 200-850 mb shear is below 30 kt and should decrease further as an anti-cyclone builds above the convection. The GFS is forecasting the disturbance to become a cyclone within 24-48 hours, and the NAM is about the same. The Florida State University phase space analysis still indicates that this will be sub-tropical in nature due to cool upper-levels, but it could end up being a significant cyclone anyways. It will be over the fairly warm waters of the northern Caribbean and Florida Straits/Gulf of Mexico for a few days as it heads northward along the western periphery of the Bermuda high, so a moderate to strong sub-tropical storm is possible. I have outlined this forecast scenario in the graphic below. The biggest story with this system will likely be rain, it appears that it will move slowly across Florida which should cause high rainfall totals. Even if the disturbance doesn't become a cyclone it would still cause alot of rain in Florida. I will continue to monitor this strange pre-season disturbance.


LINK? TIA
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Thanks StormW. :)
Member Since: Posts: Comments:

The area of disturbed weather in the Atlantic mentioned in the previous discussion continues to be a concern tonight. It has gone further south than originally projected by computer models, and is now a broad area of thunderstorm activity south of Cuba. It is more impressive than before due to decreasing shear, and appears to be coalescing into an organized area of convection. Some shear can still be seen on visible satellite imagery, but 200-850 mb shear is below 30 kt and should decrease further as an anti-cyclone builds above the convection. The GFS is forecasting the disturbance to become a cyclone within 24-48 hours, and the NAM is about the same. The Florida State University phase space analysis still indicates that this will be sub-tropical in nature due to cool upper-levels, but it could end up being a significant cyclone anyways. It will be over the fairly warm waters of the northern Caribbean and Florida Straits/Gulf of Mexico for a few days as it heads northward along the western periphery of the Bermuda high, so a moderate to strong sub-tropical storm is possible. I have outlined this forecast scenario in the graphic below. The biggest story with this system will likely be rain, it appears that it will move slowly across Florida which should cause high rainfall totals. Even if the disturbance doesn't become a cyclone it would still cause alot of rain in Florida. I will continue to monitor this strange pre-season disturbance.
Member Since: May 21, 2006 Posts: 5091 Comments: 114758
Drak, that is a nice loop, i like the colours and it does show the rotation.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Thanks Drak. I guess i should have asked my question in a different way. I need laymens terms...LOL. I guess any rotation means something is trying to form but is mid-level rotation good or bad.
Member Since: Posts: Comments:
Quoting Drakoen:

Satellite Imagery from UM


Thanks for the link.
Member Since: Posts: Comments:
Quoting Drakoen:

Satellite Imagery from UM


TY..
Member Since: July 3, 2005 Posts: 421 Comments: 127628
Quoting Patrap:
Toss that Link in if ya can Drak. Its a Keeper.

Satellite Imagery from UM
Member Since: October 28, 2006 Posts: 57 Comments: 29919
Quoting Littleninjagrl:
What does it mean when there is Mid-level rotation?


There is rotation in the mid level of the troposphere.
Member Since: October 28, 2006 Posts: 57 Comments: 29919
Toss that Link in if ya can Drak. Its a Keeper.

I got it from "properties",thanks anyway.

http://metofis.rsmas.miami.edu/~dortt/satellite/Carib/IR/atl_
Member Since: July 3, 2005 Posts: 421 Comments: 127628
Yea Guys. That's one of my favorite satellite views.
Member Since: October 28, 2006 Posts: 57 Comments: 29919
What does it mean when there is Mid-level rotation?
Member Since: Posts: Comments:
Drak, I see it also.
Member Since: Posts: Comments:
Evening Chief..Semper Paratus to yas.

Looks like you'll be doing some tropical work this week
Member Since: July 3, 2005 Posts: 421 Comments: 127628
Quoting Drakoen:
You can see the mid level rotation on satellite imagery.


I see it Drak
Member Since: September 7, 2008 Posts: 17 Comments: 1604

Viewing: 587 - 537

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
48 °F
Overcast