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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It would appear that the smaller vorticies are rotating around a broader, weaker low...

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Quoting ncstorm:
If they named this in a few..will there be a cone as well or will they wait until 5?

5
Member Since: June 17, 2011 Posts: 11 Comments: 6461
i think we would have a bigger problem if the coc was under the convec
Member Since: February 11, 2012 Posts: 0 Comments: 9718
Flood gates are being closed in Terrebonne Parish...The NWS in Lake Charles, LA is briefing now on the possible impacts of this storm on our coastline
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183430 2549N 08741W 9736 00255 0023 +230 +230 227008 009 010 002 01
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting CosmicEvents:
You're right Ta13....I'd look for a special update between 3-4EST calling this a TD or TS. The first discussion will be at 5EST. Coming up with a cone and where to place watches/warnings in this situation is why the NHC folks earn the big bucks. :)



this wont be a TD at 1st update this is going right too a TS
Member Since: May 21, 2006 Posts: 5091 Comments: 114653
Quoting bigwes6844:
I thought they had to wait till it became a td or ts right?



Not necessarily. If the intensity forecast is for a TS, you need not wait till a TS is actually named to issue a WATCH, since a WATCH is for "possible" conditions within the allotted area and time. Although it is very rare for a Watch to be issued before classification, but technically there's no reason it couldn't or would be done if the forecast strength became obvious.

It looks like this is going to make at least TS classification eventually anyway.
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upgrade or not...TS conditions exist, already, and will affect people...particularly those on the NE and E of the CoC.

Don't think it'll ever make it to hurricane strength.

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Quoting weathermanwannabe:
They will most likely post TS warnings later today from Florida to the TX-LA border and fine tune that by tomorrow. If she really blossoms tonight, we could see an upgrade to include Hurricane watches along the same swath by the 2:00 advisory tomorrow morning. Gonna be really interesting to see how strong she can get by tomorrow morning.

I think posting hurricane watches is risky at this point because of the lack of confidence in the track.
Member Since: February 11, 2012 Posts: 82 Comments: 7566
Quoting MiamiHurricanes09:


WEST WIND
Member Since: June 17, 2011 Posts: 11 Comments: 6461
Quoting Hurricanes101:


not necessarily

you could issue a wind watch or warning for an area




thats ture
Member Since: May 21, 2006 Posts: 5091 Comments: 114653
Quoting Sfloridacat5:


Comparing this to Katrina is a stretch to say the least. Katrina was a cat 5 (180 mph gusts) when it was in this location in the GOM.
Yeah true but if it gets close they still should be able to know wats going on at least. We have a lot of last minute people out here who just dont pay attention to weather. this is the most important time too.
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They will most likely post TS warnings later today from Florida to the TX-LA border and fine tune that by tomorrow. If she really blossoms tonight, we could see an upgrade to include Hurricane watches along the same swath by the 2:00 advisory tomorrow morning. Gonna be really interesting to see how strong she can get by tomorrow morning.
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1082. Grothar
.
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Quoting reedzone:


Maybe no upgrade at 5 p.m.


It's only 2:30.

How often do those updates from ATCF come out?
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1080. Patrap
Best take a deep breath first
Member Since: July 3, 2005 Posts: 419 Comments: 127371
Quite the headache. The TVCN just has it wobbling around throughout the forecasting period.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Tazmanian:




no they olny issue Warnings for TD TS and hurricanes


not necessarily

you could issue a wind watch or warning for an area
Member Since: March 10, 2010 Posts: 1 Comments: 7337
Quoting WxGeekVA:


They need to go back and see if that second swirl is closed.


2nd swirl?
Member Since: February 11, 2012 Posts: 0 Comments: 9718
You're right Ta13....I'd look for a special update between 3-4EST calling this a TD or TS. The first discussion will be at 5EST. Coming up with a cone and where to place watches/warnings in this situation is why the NHC folks earn the big bucks. :)
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1074. Walshy
About 8 percent of oil and natural gas production in the Gulf had been suspended, the U.S. government said Saturday.

MSNBC NEWS
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Quoting bigwes6844:
I thought they had to wait till it became a td or ts right?




no they olny issue Warnings for TD TS and hurricanes
Member Since: May 21, 2006 Posts: 5091 Comments: 114653
Looks like HHs are finding multiple centers within a close area, maybe the center is relocating further East or just a very broad center.
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Quoting ncstorm:
Look towards africa..

Supposedly the GFS is the best of all models in detecting cape verde system correct?
Member Since: October 15, 2011 Posts: 0 Comments: 3958
Quoting aislinnpaps:


And some people will be caught unaware. I'm amazed at how many friends knew nothing about what has been going on in the Gulf.


I've got some family down in Panama City and Pensacola... might wanna let them know...
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Normally we don't get a renumber till 3:30 or so, Recon aint done.
Member Since: July 8, 2005 Posts: 259 Comments: 23499
Quoting weatherh98:


They can issue Warnings on an invest
I thought they had to wait till it became a td or ts right?
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Quoting ncstorm:
If they named this..will there be a cone as well or will they wait until 5?

If they name this the advisory won't come out until 5PM EDT.
Member Since: July 6, 2010 Posts: 112 Comments: 31336
Well if the plane would just fly over that Buoy generating all that wind we have a storm.
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1065. Patrap
18:28:30Z 26.067N 87.517W 973.5 mb
(~ 28.75 inHg) 259 meters
(~ 850 feet) 1002.6 mb
(~ 29.61 inHg) - From 80° at 9 knots
(From the E at ~ 10.3 mph) 23.6°C
(~ 74.5°F) 22.9°C
(~ 73.2°F) 10 knots
(~ 11.5 mph) 8 knots
(~ 9.2 mph) 3 mm/hr
(~ 0.12 in/hr) 7.2 knots (~ 8.3 mph)
80.0%
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 toEst. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 18:19:00Z (first observation), the observation was 288 miles (463 km) to the S (178°) from Pensacola, FL, USA.
Member Since: July 3, 2005 Posts: 419 Comments: 127371
Quoting HurricaneHunterJoe:
Looks like HH gonna pinpoint that further east circ?


That's probably just a Meso embedded in the convection, but I did expect this and they'll probably fly through both areas several times to figure out just what's going on.
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some convection over the coc and were off, could be like beryl

my only wonder is why the coc is going s
storm has nice outflow lines though, especially around the bahamas and cuba:
Member Since: February 11, 2012 Posts: 0 Comments: 9718
Quoting bigwes6844:
I know because im on the way to work in a few and people are going around like nothing is going on. Then when i say oh we have a storm in the GOM, then theyre concern all of sudden. Uthink people would have learned from Katrina but some hasnt


Comparing this to Katrina is a stretch to say the least. Katrina was a cat 5 (180 mph gusts) when it was in this location in the GOM.
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Quoting MiamiHurricanes09:
AL, 96, 2012062318, , BEST, 0, 260N, 876W, 40, 1001, LO,
This will likely stop the debate if it is going to be upgrade to td or to ts.if it is upgrade it will be to Ts Debby.
Member Since: October 15, 2011 Posts: 0 Comments: 3958
Quoting GeorgiaStormz:
See the wind shift, google earth has terrible vis but the coc is under there



They need to go back and see if that second swirl is closed.
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Quoting TropicalAnalystwx13:

That's the typical 18Z update. Look for a renumber between 3PM EDT and 4PM EDT.


Ahh, I see, thanks.
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1058. ncstorm
If they named this in a few..will there be a cone as well or will they wait until 5?
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Quoting bigwes6844:
wow this storm is gonna be a last min. decision and watches and warning are gonna be huge probably from texas to Florida


They can issue Warnings on an invest
Member Since: June 17, 2011 Posts: 11 Comments: 6461
1056. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 36665
with winds of 45 mph for 96L i really see them puting up a hurricane watch for some one
Member Since: May 21, 2006 Posts: 5091 Comments: 114653
1054. ncstorm
144 hours out

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1053. Walshy
QUE RENUMBER...INBOUND SOON
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1052. dewfree
25°20'24" N 87°27'36" W
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Quoting aislinnpaps:


And some people will be caught unaware. I'm amazed at how many friends knew nothing about what has been going on in the Gulf.
I know because im on the way to work in a few and people are going around like nothing is going on. Then when i say oh we have a storm in the GOM, then theyre concern all of sudden. Uthink people would have learned from Katrina but some hasnt
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Observation Time: Saturday, 17:59Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 26.6N 87.2W
Location: 265 miles (427 km) to the S (180°) from Pensacola, FL, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 340 meters
Flight Level Wind: From 110° at 17 knots (From the ESE at ~ 19.5 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 24°C
Flight Level Dew Point: 24°C
Weather (within 30 nautical miles): Thunderstorm(s)
Mean Sea Level Pressure (MSLP): 1001 mb (extrapolated)
Member Since: February 11, 2012 Posts: 0 Comments: 9718
1048. Patrap
Member Since: July 3, 2005 Posts: 419 Comments: 127371
Quoting reedzone:


Maybe no upgrade at 5 p.m.


recon is in the system, that usually overrides anything the atcf puts out
Member Since: March 10, 2010 Posts: 1 Comments: 7337
46 mph.. thats debby huh?
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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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