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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Tropical Storm watches are about to be issued
Member Since: August 14, 2010 Posts: 0 Comments: 183
Quoting LightningCharmer:

There are now:

National Weather Service Enhanced Radar Image Loop - Key West, FL Radar

Be careful out there.
TY
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NHC might withhold the advisory until a little later if we're dealing with 70mph flight level winds.
Member Since: July 8, 2005 Posts: 259 Comments: 23898
lol ya
Quoting weatherh98:
I think the NHC made the decision to go through this thunderstormds just to see now
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bad news is if that warned cell holds together till immokalee lots of folks there live in trailers
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man this thing is all most hurricane
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Quoting DocNDswamp:
As others have mentioned, close up of vis sat imagery from NASA site clearly shows the LLC has been comprised of 2 swirls rotating around each other for several hrs, drifting SSW by about a full degree latitude from earlier position this morn... Latest view or so suggests might be consolidating some and shifting EWD, still a rather large, elongated / distended LLC... and good grief, seen many sheared TC's with displaced convection, but this one is tough call in meeting criteria with heaviest convection (and perhaps it's greatest mid level vorticity) over 100 miles to the east of the sfc low! Little doubt the sfc low pressure and winds are strong enough, just if its organized enough vertically to call by this point...


Very well said. I agree. It looks pathetic right now. Naked swirl void of any deep convection. I would see maybe a 40 or 45mph Tropical Storm, with a track to the North Texas Coast.
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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
Member Since: September 18, 2010 Posts: 0 Comments: 5220
Quoting WxGeekVA:
The wind profile is almost subtropical in nature....

Note the key word ALMOST


yes but it isnt because it has thse thunderstorms. but if it didnt it would be subtropical
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I think it is spliting in two, just like the GFS predicted.
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Debby is much stronger than I thought it would be at this point.
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Quoting weatherh98:


65 mph or so then surface would be roughly 55


As a rule, Dr. Steve Lyons used to say that flight level in Knots was roughly equal to MPH at the surface, so yeah.

57knts flight level ~= 57mph surface winds.

But that could have been a local thunderstorm, so that doesn't necessarily mean they'll make that the official wind speed.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Just heard on twc that the flight level picked up on 69mph winds
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I think the NHC made the decision to go through this thunderstormds just to see now
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Quoting Drakoen:


No, I don't think that the GFS solution is more probable than the UKMET. I'm pointing out the subtleties in the models that are making the difference in the tracks of Debby.
Thank you!!
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Quoting unf97:


That's seemingly true. It seems Seidel always get the worst end of the stick in covering these storms. He was here in Jacksonville covering Beryl's landfall last month.

Cantore will be in Pensacola covering the system tomorrow.


Well we now know that Pensacola is 100% safe from Debby cause Cantore is the storm shield
Member Since: August 14, 2010 Posts: 0 Comments: 183
Quoting masonsnana:
More tornado warnings in SWF but not a tornado watch box yet?

There are now:

National Weather Service Enhanced Radar Image Loop - Key West, FL Radar

Be careful out there.
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Quoting HurricaneHunterJoe:


There was on the Tampa Nexrad Radar
Ok ty :) I have the weather radio on and all I've heard were the warnings not the watches..
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Quoting Sfloridacat5:
Public reporting tornado on the ground (Collier County Fl.)
OMG! Hope folks down there are heeding the warnings.
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Quoting Stormchaser2007:
60-knot flight level winds!




omg this is not good
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The wind profile is almost subtropical in nature....

Note the key word ALMOST
Member Since: September 3, 2011 Posts: 13 Comments: 3470
I'm telling you heads up people in S. Fl and the keys the weather coming up the straits looks scary and it's been very calm wind wise in Miami, the quiet before the you no what sometimes.Anybody, Patrap want to post a loop.
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Debby is a 60 to 65mph storm !!:)
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60-knot flight level winds!
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1672. Levi32
SFMR winds well above tropical storm force:

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good news is where that cell passes east of me very few people live out there
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1670. unf97
Quoting NCHurricane2009:

The way I look at it...they are placing them where their all already impacts. The east side of Debby has been lashing Florida with heavy rains...maybe some light gusty winds...and possible tornadoes...the impacts being worse the closer you are to the Gulf coast of Florida.


That's seemingly true. It seems Seidel always get the worst end of the stick in covering these storms. He was here in Jacksonville covering Beryl's landfall last month.

Cantore will be in Pensacola covering the system tomorrow.
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Quoting masonsnana:
More tornado warnings in SWF but not a tornado watch box yet?


There was on the Tampa Nexrad Radar
Member Since: September 18, 2010 Posts: 0 Comments: 5220
t. Lvl. Wind (30s): From 143° at 60 knots (From the SE at ~ 69.0 mph)
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Public reporting tornado on the ground (Collier County Fl.)
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If Debby is a 60mph storm all ready maybe Joe's whacky forecast may not be that off.
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Quoting FLWeatherFreak91:
Thanks for reporting :) It's heading in my general direction
Yes,I called my friend in Estero, he told me the storm was extreme
Member Since: September 18, 2010 Posts: 0 Comments: 5220
Whether Debby is pretty or ugly...it still has some nasty weather with it right now.
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1663. Drakoen
Quoting Hurricane1956:
Hello,if I may ask what this all means? that you believe that the GFS solution is more probable than the UKMET?,I'm not a weather expert,but has being following hurricanes for more than 25 years,my gut feeling was always with the GFS eastern solution,I'm probably wrong,but looking at the whole picture in the Gulf of Mexico and the way this system wants to go East this is my 2 cents worth opinion.


No, I don't think that the GFS solution is more probable than the UKMET. I'm pointing out the subtleties in the models that are making the difference in the tracks of Debby.
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Local news (Ft. Myers channel 2)showing 2 separate tornado warnings.
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1661. nigel20
Quoting TropicalAnalystwx13:
Recon has found peak flight-level winds of 57 knots.

Wow!
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More tornado warnings in SWF but not a tornado watch box yet?
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Alright lets not try to flood this blog with the first advisory post. One or two will do.
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Quoting TropicalAnalystwx13:
Uncontaminated surface winds of 49 knots.



that would put winds right a round 60mph
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1657. gator23
Quoting trHUrrIXC5MMX:
someone could not wait...

UH THEY ARE NOT SUPPOSED TO DO THAT.
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Quoting TropicalAnalystwx13:
Uncontaminated surface winds of 49 knots.


.9"/hr rates with 43 knot flight level...

Suspicious
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Quoting FLWeatherFreak91:
I'm debating whether or not the big slug of convection is going to continue with its momentum NE into west florida, or if it is going to wrap around the center and just scrape the coast for a couple hours... Any opinions on this west coasters?


Don't know if Im late on this or if it was already posted. Tornado warnings for 2 tornados in Collier County
Member Since: September 18, 2010 Posts: 0 Comments: 5220
Quoting BrickellBreeze:


What if the center redevelops under the convection?


Probably NOT going to happen at this point. The LLC at 26N 87.6W is too powerful and well developed now.
Member Since: January 25, 2012 Posts: 33 Comments: 1520
Quoting stormchaser19:
I THINK AT 5:00 PM WILL BE DEBBY, I CANT WAIT TO SEE THE CONE OF ERROR OF THE NATIONAL HURRICANE CENTER

GFS OR ECMWF?
FLORIDA OR TEXAS?

THIS IS GETTING GOOD!!!!!LOL


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

THE CONE OF DOOM, DEATH, and DISTRUCTION
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Quoting floridaT:
that tornado warned cell east of naples just passed about 1 mile east of me. looked intense very low fast moving clouds and frequent lightning.
Thanks for reporting :) It's heading in my general direction
Member Since: December 1, 2006 Posts: 2 Comments: 3619
As others have mentioned, close up of vis sat imagery from NASA site clearly shows the LLC has been comprised of 2 swirls rotating around each other for several hrs, drifting SSW by about a full degree latitude from earlier position this morn... Latest view or so suggests might be consolidating some and shifting EWD, still a rather large, elongated / distended LLC... and good grief, seen many sheared TC's with displaced convection, but this one is tough call in meeting criteria with heaviest convection (and perhaps it's greatest mid level vorticity) over 100 miles to the east of the sfc low! Little doubt the sfc low pressure and winds are strong enough, just if its organized enough vertically to call by this point...
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Uncontaminated surface winds of 49 knots.
Member Since: July 6, 2010 Posts: 113 Comments: 31906
that tornado warned cell east of naples just passed about 1 mile east of me. looked intense very low fast moving clouds and frequent lightning.
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1647. Levi32
Flight-level winds are punching it in the thunderstorms well east of the center:

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Quoting Drakoen:
Here's a great link to compare the 500mb patterns among various models. As a test I chose the GFS and the UKMET to see the different 500mb spatial differences among opposing models. The trough on the GFS extends about 700km farther south than the UKMET and the ridge extends about 250km farther eastward on the UKMET than on the GFS.

HPC 500mb models
Hello,if I may ask what this all means? that you believe that the GFS solution is more probable than the UKMET?,I'm not a weather expert,but has being following hurricanes for more than 25 years,my gut feeling was always with the GFS eastern solution,I'm probably wrong,but looking at the whole picture in the Gulf of Mexico and the way this system wants to go East this is my 2 cents worth opinion.
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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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