Gulf of Mexico disturbance 96L close to tropical storm status

By: Dr. Jeff Masters , 1:26 PM GMT on June 23, 2012

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An area of low pressure and heavy thunderstorms in the Central Gulf of Mexico (96L) is close to tropical depression or tropical storm status, and all interests along the Gulf of Mexico coast should pay attention to the progress of this disturbance. The disturbance has brought heavy rains to Western Cuba, South Florida, and Mexico's Yucatan Peninsula over the past two days, but the disturbance's heaviest rains are located well offshore over the Eastern Gulf of Mexico, where heavy thunderstorms are generating winds near tropical storm-force. A buoy 243 miles east of Naples, FL measured sustained winds of 31 mph, gusting to 38 mph, with 10-foot waves, at 8 am EDT Saturday morning. Our wundermap for the surrounding ocean areas shows a large region of the northern and eastern Gulf of Mexico is experiencing winds of 20 - 30 mph. Satellite-based surface wind measurements taken at 7:22 am EDT Saturday from the newly-available Oceansat-2 scatterometer, courtesy of India, showed a broad, elongated surface circulation over the Central Gulf of Mexico that was not well defined. The satellite saw top surface winds of 30 - 40 mph over the Eastern Gulf of Mexico. Visible satellite loops show that the circulation of 96L has become more defined this morning, and the heavy thunderstorm activity is slowly expanding and growing more intense. Upper-level winds out of the west are creating a moderate 10 - 20 knots of wind shear over the region. Water vapor satellite loops show a modest region of dry air over the Central Gulf of Mexico, which is interfering with development and keeping the western side of 96L's circulation free of heavy thunderstorms. Ocean temperatures are about 28.5°C (83°F) in the Central Gulf of Mexico, which is about 1°F above average. A hurricane hunter mission is scheduled to investigate 96L this afternoon to see if a tropical depression or tropical storm has formed.


Figure 1. Saturday morning satellite image of tropical disturbance 96L in the Gulf of Mexico.


Figure 2. Radar-estimated precipitation for South Florida from tropical disturbance 96L.

Forecast for 96L
Wind shear is predicted to remain in the moderate range through Sunday night, which is likely low enough to allow 96L to develop into a tropical depression or tropical storm by Sunday; NHC gave 96L a 90% chance of developing into a tropical depression by Monday morning, in their 8am EDT Tropical Weather Outlook. The future path of 96L is still unclear. The disturbance will drift slowly northwards through Sunday night, which will likely bring heavy rains of 2 - 4 inches to the Gulf Coast from Central Louisiana to Central Florida. A storm surge of 1 - 3 feet is also likely along the Southeast Louisiana coast on Sunday; coastal flood advisories have already been posted there. By Monday, the majority of the reliable models, including the ECMWF, NOGAPS, HWRF, and UKMET, agree that a ridge of high pressure will build in over the Southern U.S., forcing 96L westwards across the Gulf of Mexico and into South Texas by Wednesday. However, the GFS model, which has been our 2nd most reliable track model over the past two years (behind the ECMWF), has consistently been predicting that a trough of low pressure pushing off of the U.S. East Coast will be capable of grabbing the disturbance and accelerating it to the northeast across Florida north of Tampa Bay on Monday. The GFDL model splits the difference between these extremes, taking 96L northwards to a landfall near the Alabama/Florida border on Tuesday. Given that the majority of the models predict a westward track to Texas, that should be viewed as the most probable path for 96L, but this is a low-confidence forecast. None of the models is predicting 96L will become a hurricane, and the SHIPS model is predicting just a 4% chance of rapid intensification for 96L. Given the moderate levels of wind shear and dry air over the Gulf, only slow to modest intensification of 96L is likely over the next few days.

Jeff Masters

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Quoting wakd3Xn04:
just got done with a round trip Sarasota to Naples and back to pick up daughter for summer break. Rain the whole way, both ways. Nothing heavy, just steady.


Heavy weather is just moving into S.W. Fl. Gentle rain all day in Fort Myers but now lot of thunder with strong storms in the area.
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1795. rxse7en
Quoting tornadodude:
Classic hook.
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Quoting Tazmanian:
this think when shear drops too all most 0 this thing will really take off


It is a very large system and it has all the fuel in the world. I agree once this becomes stacked. It's only a ULAC over it away from a rapid intensification process.
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Quoting CybrTeddy:
Advisory might be held back a while guys, remember TS warnings have to go out, and now new data is coming in showing 70mph flight level winds, that translates to 60mph on the surface easily.


Watches and warnings were issued 20 mins ago
Member Since: August 14, 2010 Posts: 0 Comments: 183
Quoting HurricaneHunterJoe:


Yes,I pretty much shuts off north of Tampaand the feeder band goes back west toward the center.


.
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Quoting Tazmanian:
guys for get the
ATCF file for right now we may have a 50 too 60mph TS on are hands


I agree, but I don't think a relatively small area of high winds reported from the plane will make the NHC initiate advisories at any higher than 45mph. If the plane finds any more winds that high, we'll probably get the next full advisory at 8:00pm EDT to up the winds.
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1790. icmoore
Quoting HurricaneHunterJoe:
That feeder band that contained those tornados only goes inland like 20 miles and then its spotty thunderstorms,but along the coast its all hell breaking lose from the keys to tampa


Not sure I like hearing that but we all need to keep our heads up!
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Quoting Tazmanian:



yes they have fould 61kt fight level winds and a lot of 50kt winds
In that case the 5p.m advisory should have 50kt sustained winds. If they don't, I'm sure the discussion will explain it.
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Advisory might be held back a while guys, remember TS warnings have to go out, and now new data is coming in showing 70mph flight level winds, that translates to 60mph on the surface easily.
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Quoting trHUrrIXC5MMX:


excuse me... he or she asked ME! thank you very much

Does it matter how he/she asked? We're on a community forum, so anybody can answer. Chill.
Member Since: July 6, 2010 Posts: 113 Comments: 32275
Quoting MiamiHurricanes09:
Recon find anything more intense than 40kt winds?


yes
Member Since: June 17, 2011 Posts: 11 Comments: 6539
1785. Patrap
Product: Air Force High Density (HDOB) Message (URNT15 KNHC)

Transmitted: 23rd day of the month at 20:26Z

Date: June 23, 2012

Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 302)

Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)

Mission Number: 1

Observation Number: 30


20:38:30Z 27.583N 85.000W 962.9 mb

(~ 28.43 inHg) 409 meters
(~ 1,342 feet) - - From 117° at 42 knots
(From the ESE at ~ 48.3 mph) 19.9°C*
(~ 67.8°F*) -* 44 knots
(~ 50.6 mph) 29 knots
(~ 33.3 mph) 8 mm/hr
(~ 0.31 in/hr) 27.7 knots (~ 31.8 mph)
65.9%

Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic
At 20:29:00Z (first observation), the observation was 169 miles (272 km) to the WSW (247°) from Tampa, FL, USA.

At 20:38:30Z (last observation), the observation was 157 miles (253 km) to the W (260°) from Tampa, FL, USA.
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The next 15 hours or so, particularly over night, is going to suck in the keys and lower mainland Florida.

There are quite a few more severe thunderstorms headed north in the squall, and possibly tornadic potential, as they are isolated enough.

For probably the next 12 to 18, the isolated tornadoes are going to be the biggest threat on land.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting trHUrrIXC5MMX:


excuse me... he or she asked ME! thank you very much
Why are you upset? I've got a valid point. Chill. :-)
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Quoting MiamiHurricanes09:
Recon find anything more intense than 40kt winds?



yes they have fould 61kt fight level winds and a lot of 50kt winds
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Quoting TropicalAnalystwx13:
Expect the advisory within the next 7 minutes.


6.34 actually
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting MiamiHurricanes09:
Recon find anything more intense than 40kt winds?


Yes...they even found 60 kt flight level.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting cyclonekid:
Please look at comment 1745. Thank you.


excuse me... he or she asked ME! thank you very much
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Quoting tornadodude:
Anticyclonic???
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1777. Patrap
Mobile Long Range Radar



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CROW
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just got done with a round trip Sarasota to Naples and back to pick up daughter for summer break. Rain the whole way, both ways. Nothing heavy, just steady.
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1774. Gorty
It looks so bad. I can't believe that she has at least 50 mph winds...
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Possible T.S. Watches at 5 me thinks
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I saw a flash on the screen for TWC that said Debby has formed about 20 minutes ago
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Recon find anything more intense than 40kt winds?
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Quoting cyclonekid:
It's possible, but it doesn't give the direction or speed of movement.


because it was only part of it
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting trHUrrIXC5MMX:


ATCF , look it up
Please look at comment 1745. Thank you.
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All in S FL Rain is coming now!!:)
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1767. Patrap
I'm sure some phones are ringing.
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Expect the advisory within the next 7 minutes.
Member Since: July 6, 2010 Posts: 113 Comments: 32275
Quoting WxGeekVA:
It's F5F5F5F5F5F5F5F5F5F5F5F5 TIME!!!


just click on the NHC logo on the website...easier
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Did that circulation west of the convection dissipate?
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1763. Patrap
20:15 Rainbow

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Quoting Patrap:
Time: 20:20:30Z
Coordinates: 26.4833N 85.0W
Acft. Static Air Press: 963.0 mb (~ 28.44 inHg)
Acft. Geopotential Hgt: 381 meters (~ 1,250 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 143° at 60 knots (From the SE at ~ 69.0 mph)
Air Temp: 20.4°C* (~ 68.7°F*)


Note that fer sure sp.
TWC did
Member Since: June 17, 2011 Posts: 11 Comments: 6539
The model maps are updated to reflect Debby even though NHC isn't showing it yet...



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Quoting weatherh98:


get it right. on this site its....

THE CONE OF DOOM, DEATH, and DISTRUCTION


DESTRUCTION
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1759. Patrap
Time: 20:20:30Z
Coordinates: 26.4833N 85.0W
Acft. Static Air Press: 963.0 mb (~ 28.44 inHg)
Acft. Geopotential Hgt: 381 meters (~ 1,250 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 143° at 60 knots (From the SE at ~ 69.0 mph)
Air Temp: 20.4°C* (~ 68.7°F*)


Note that fer sure sp.
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1758. LargoFl
LOOD ADVISORY
NATIONAL WEATHER SERVICE JACKSONVILLE FL
407 PM EDT SAT JUN 23 2012

FLC089-GAC049-232200-
/O.NEW.KJAX.FA.Y.0044.120623T2007Z-120623T2200Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
CHARLTON GA-NASSAU FL-
407 PM EDT SAT JUN 23 2012

THE NATIONAL WEATHER SERVICE IN JACKSONVILLE HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR MINOR FLOODING OF POOR
DRAINAGE AREAS IN...
WESTERN NASSAU COUNTY IN NORTHEAST FLORIDA...
SOUTHERN CHARLTON COUNTY IN SOUTHEAST GEORGIA...

* UNTIL 600 PM EDT

* AT 405 PM EDT WEATHER SERVICE DOPPLER RADAR INDICATED HEAVY RAIN
EXTENDING FROM WESTERN NASSAU COUNTY TO NEAR ST GEORGE AND
DRIFTING NORTHWEST. THERE HAVE BEEN DOPPLER ESTIMATES OF 1 TO
INCHES WITH AN ADDITIONAL 2 INCHES POSSIBLE WHICH COULD CAUSE
LOCALIZED FLOODING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...
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1757. Walshy
If Debby gets retired, I say we replace it with Debra.

Too early?
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Quoting cyclonekid:
I don't understand how they have that information.


ATCF , look it up
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TWC are anxious for them to name this.They've been talking about it all afternoon(like they should).The title is called "tracking tropical storms".They all ready likely know this us a tropical storm.Just don't want to confuse viewers yet.
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guys for get the
ATCF file for right now we may have a 50 too 60mph TS on are hands
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1753. WxLogic
Good evening... Looks like the HH have found quite a bit of TS force winds.
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1752. Patrap
Still Brisk out at the Plane 27N 85W
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Quoting TropicalAnalystwx13:

NHC updates all media before the advisory.


I missed the NHC conf call cause one of our stations went off the air :(


And whoever is hot linking images from Levi's site it's messing up the blog
Member Since: August 14, 2010 Posts: 0 Comments: 183
Time: 20:20:30Z
Coordinates: 26.4833N 85.0W
Acft. Static Air Press: 963.0 mb (~ 28.44 inHg)
Acft. Geopotential Hgt: 381 meters (~ 1,250 feet)
Extrap. Sfc. Press: -
D-value: -
Flt. Lvl. Wind (30s): From 143° at 60 knots (From the SE at ~ 69.0 mph)
Air Temp: 20.4°C* (~ 68.7°F*)
Dew Pt: -*
Peak (10s) Flt. Lvl. Wind: 61 knots (~ 70.1 mph)
SFMR Peak (10s) Sfc. Wind: 39 knots (~ 44.8 mph)
SFMR Rain Rate: 6 mm/hr (~ 0.24 in/hr)
(*) Denotes suspect data
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Quoting FLWeatherFreak91:
Hell must not be all that bad because I've only had spotty raindrops falling and calm wind for the past 3 hours here north of Tampa.


Yes,I pretty much shuts off north of Tampaand the feeder band goes back west toward the center.
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1747. cg2916
Navy still has 96L because although there is an 04L file, there was no renumber.
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Reports of tornado damage by news crews in Naples Fl.
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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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