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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12z UKMET
Member Since: June 9, 2007 Posts: 4 Comments: 15945
Quoting WxGeekVA:
I mapped out the low clouds from the recent NASA Hi-res pass, and from what I can tell we have a slightly elongated low with 2 eddies in it that are merging. This should be declared a T.S. after the Hurricane Hunters are done.



BTW do you all like me doing these drawings? I do them because I think it helps everyone understand things a little simpler and easier to understand.


Nice drawings. And greatly appreciated.
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Amateur questions:

1) Is the naked swirl aka soon to be Debby really moving towards the SW? I swear it looks that way on the visible...

2) Why would it be moving SW right now? I thought she was supposed to be moving North (for now)... slowly stop, maybe meander around for a while, then make her turn E or W depending how things unfold (the strength of the storm, trough, and ridge)???

Thanks in advance for any replies.
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My kid wants the computer........Be back later.... :)
Member Since: August 8, 2006 Posts: 0 Comments: 9323
Quoting allancalderini:
We probably have ts Debby right now or ta least a td it will be interesting which forecast track does the NHC use to the East or to the west.
The East.
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Quoting msglfcst:


Katrina hit Mississippi.....not Louisiana.


Just a hint to my fellow Mississippian, don't start that argument. :-)

However, Katrina's first Gulf landfall was in Louisiana.
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96L Long Floater - Rainbow Color Imagery Loop
Member Since: July 3, 2005 Posts: 426 Comments: 129089
I mapped out the low clouds from the recent NASA Hi-res pass, and from what I can tell we have a slightly elongated low with 2 eddies in it that are merging. This should be declared a T.S. after the Hurricane Hunters are done.



BTW do you all like me doing these drawings? I do them because I think it helps everyone understand things a little simpler and easier to understand.
Member Since: September 3, 2011 Posts: 13 Comments: 3476
makin a prediction here...new "center" at about 25n and 85w...see some low clouds not centering around the naked swirl...
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Quoting Patrap:
Ike is on FB, he just dosen't yakk here anymore.


Ike was a downcaster.
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Quoting Patrap:
Shear is the detriment to 96L.

The CoC is whifferdilling around to the South..as the Convection imparts a tug from the east on it.

Nothing is "spitting out"



I was referring to the history, not today. Last night the LLC near the Yucatan was clearly more dominate, and then it switched to where it is now...there it's remained, and will remain.
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17:28:30Z 25.417N 87.383W 973.4 mb
(~ 28.74 inHg) 267 meters
(~ 876 feet) 1003.5 mb
(~ 29.63 inHg) - From 239° at 19 knots
(From the WSW at ~ 21.8 mph) 23.0°C*
(~ 73.4°F*) 23.0°C*
(~ 73.4°F*) 19 knots
(~ 21.8 mph) 14 knots
(~ 16.1 mph) 1 mm/hr
(~ 0.04 in/hr) 14.0 knots (~ 16.1 mph)
73.7%
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 17:19:00Z (first observation), the observation was 323 miles (520 km) to the SSE (155°) from New Orleans, LA, USA.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
200 miles west of Naples:

Station 42003
NDBC
Location: 26.044N 85.612W
Date: Sat, 23 Jun 2012 16:50:00 UTC

Winds: SE (140°) at 31.1 kt gusting to 38.9 kt
Significant Wave Height: 13.8 ft
Dominant Wave Period: 11 sec
Mean Wave Direction: SSE (163°)
Atmospheric Pressure: 29.65 in and falling
Air Temperature: 78.6 F
Water Temperature: 82.4 F

She is generating TS force winds already in some quadrants; once they are able to close off the center, whether this afternoon of later today, they are going to skip right to TS.
Member Since: August 8, 2006 Posts: 0 Comments: 9323
Quoting Hurricanes101:
circulation is moving South now and would not shock me if it spins back east towards the convection again


Exactly my thinking..
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Quoting hydrus:
Category One Hurricane

Maximum Sustained Wind Speed: 74-95 miles per hour
Damage Category: Minimal
Approximate Pressure: Above 980 mb
Approximate Storm Surge: 3-5 feet
Examples: Hurricane Lili (2002) in Louisiana; Hurricane Gaston (2004) in South Carolina

Category Two Hurricane

Maximum Sustained Wind Speed: 96-110 miles per hour
Damage Category: Moderate
Approximate Pressure: 979-965 mb
Approximate Storm Surge: 6-8 feet
Example: Hurricane Isabel (2003) in North Carolina

Category Three Hurricane

Maximum Sustained Wind Speed: 111-129 miles per hour
Damage Category: Extensive
Approximate Pressure: 964-945 mb
Approximate Storm Surge: 9-12 feet
Examples: Hurricane Katrina (2005) in Louisiana; Hurricane Jeanne (2004) in Florida; Hurricane Ivan (2004) in Alabama

Category Four Hurricane

Maximum Sustained Wind Speed: 130-156 miles per hour
Damage Category: Extreme
Approximate Pressure: 944-920 mb
Approximate Storm Surge: 13-18 feet
Example: Hurricane Charley (2004) in Florida; Hurricane Iniki (1992) in Hawaii; the Galveston Hurricane (1900) in Texas

Category Five Hurricane

Maximum Sustained Wind Speed: 157 miles per hour and higher
Damage Category: Catastrophic
Approximate Pressure: Below 920 mb
Approximate Storm Surge: More than 18 feet
Examples: Only three Category 5 hurricanes have struck the United States since records began: The Labor Day Hurricane (1935) in the Florida Keyes, Hurricane Camille (1969) near the mouth of the Mississippi River, and Hurricane Andrew (1992) in Florida


Katrina hit Mississippi.....not Louisiana.
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I agree, but even if it's on the fringe they will normally classify it to get advisories posted.

Just my experience- What do i know....
Member Since: November 19, 2008 Posts: 0 Comments: 23
Quoting Patrap:
Shear is the detriment to 96L.

The CoC is whifferdilling around to the South..as the Convection imparts a tug from the east on it.

Nothing is "spitting out"

whfferdilling???
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The HWRF 12z still taking 96L westward.

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Quoting FSUCOOPman:


Agreed...no doubt, now. We finally have a definitive fix!

Just took a few days to get there.


The CoC we see has been there since 06Z early this am.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Well, we'll see what happens here in a few hours. It has definitely ejected several llc's in the last few days. This one may hang on. Part of the problem with vort's rotating within the larger gyre of the broad low.
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Looks like Africa is about to collide with Florida!
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Ike is on FB, he just dosen't yakk here anymore.
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting MississippiWx:
I don't think there is much doubt about finding a closed low.



Agreed...no doubt, now. We finally have a definitive fix!

Just took a few days to get there.
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Quoting KORBIN:
I think they will classify this because of it's proximity to land. It's just too close to the E Gulf Coast to take any chances.


They will classify it because it meets the criteria, not because it is close to land.
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Shear is the detriment to 96L.

The CoC is whifferdilling around to the South..as the Convection imparts a tug from the east on it.

Nothing is "spitting out"

Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting MississippiWx:
About Ike, maybe he wasn't banned. His blog still shows up. Hope nothing happened with his health.

Link
bloggers.dont.get.old.they.just.fade.away
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I don't think there is much doubt about finding a closed low.

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circulation is moving South now and would not shock me if it spins back east towards the convection again
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I think they will classify this because of it's proximity to land. It's just too close to the E Gulf Coast to take any chances.
Member Since: November 19, 2008 Posts: 0 Comments: 23
Quoting jpsb:
Wasn't Anita a 200mph storm? Crossed the Gulf and went into MX, correct? I do not see 96L as another 77 Anita.


Member Since: June 9, 2007 Posts: 4 Comments: 15945
Quoting LargoFl:


Shows up well spitting out a LLC she didnt like and finding one she does.......lol
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these forcast are confusing me they need to make up there mind 50/50 for texas and florida thats just crazy
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I'd say 90-100% on the next TWO.
Member Since: June 9, 2007 Posts: 4 Comments: 15945
Quoting FSUCOOPman:


Definitely a recurring theme with 96L... I was trying to count how many different LLCs I watched get spit out in the last 36 hours. I think we're up to about 4.


Yeah moving rapidly SW away from the convection.
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761. jpsb
Quoting windshear1993:
could hurricane anita from 1977 be an anologue??
Wasn't Anita a 200mph storm? Crossed the Gulf and went into MX, correct? I do not see 96L as another 77 Anita.
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There is only one center.

Member Since: July 3, 2005 Posts: 426 Comments: 129089
Seeing WSW winds so I'm sure will see a Tropical Storm. When they fly into the strongest wind field to the East they'll find their T.S. winds.
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Click on FRONTS and MSLP here.

96L Long Floater - RGB Color Imagery Loop
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting charlottefl:


If you look at the latest vis, that low level swirl is being ejected from the convection off to the West. Seems to be a pattern with this system.


Definitely a recurring theme with 96L... I was trying to count how many different LLCs I watched get spit out in the last 36 hours. I think we're up to about 4.
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Lordy,..

: )
Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting charlottefl:


If you look at the latest vis, that low level swirl is being ejected from the convection off to the West. Seems to be a pattern with this system.


It's the actual center and it will remain dominant.
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Quoting MississippiWx:


Looks like we pinpointed the center last night, Coop. Hope you're doing well today.


Back atcha, MSWX!

even a blind squirrel finds a nut, some days! :-)

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Quoting reedzone:
If and a big IF wind shear does relax and the ULL pushes away. With the warm temps in the GOM.. This could really turn out to be a dangerous storm.. Big IF though.. Dry air isn't a problem, outflow is impressive, and it's got a nice tight (naked) LLC. We'll see what happens. Some fo the models predicting "Hurricane" are not off if wind shear does indeed do what it's forecast to do, which is decrease.


If that scenario plays out, She will have the Northern Gulf all to herself to do with as she pleases....if she does go towards the West, for however long, the coast is going be really battered and lots of beach erosion along the Florida Emerald Coast.
Member Since: August 8, 2006 Posts: 0 Comments: 9323
We probably have ts Debby right now or ta least a td it will be interesting which forecast track does the NHC use to the East or to the west.
Member Since: October 15, 2011 Posts: 0 Comments: 4448
Quoting MississippiWx:


Looks like we pinpointed the center last night, Coop. Hope you're doing well today.


If you look at the latest vis, that low level swirl is being ejected from the convection off to the West. Seems to be a pattern with this system.
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96L Long Floater - RGB Color Imagery Loop

click image for Loop

Member Since: July 3, 2005 Posts: 426 Comments: 129089
Quoting Doppler22:
I wanted to do a poll :)

so Debby may form in the Gulf but how strong will she peak as?
A) Low End Tropical Storm
B) Upper end Tropical Storm
C) Minimal Hurricane (Categories 1 and 2)
D) Major Hurricane
E) Won't develope



B
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Quoting FSUCOOPman:


Those coords are right where the naked swirl is.


Looks like we pinpointed the center last night, Coop. Hope you're doing well today.
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Quoting hurricanehunter27:
...In meteorological terms its a minimal hurricane. That is all I am going to say about that.


*cough* MODERATE *cough*
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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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