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 Patrap:


No, the mean coc is well embedded in the Grids, its the Upper air steering that's giving the Models trouble on a consensus solution.


so, no matter where the models initialize the CoC the upper atmosphere is going to do the same thing with steering?

I don't understand that.

Wouldn't the position of the CoC ultimately be affected differently by the upper atmosphere depending on its coordinates?

Learning, Pat...be easy on me.
Member Since: August 29, 2008 Posts: 0 Comments: 376
Quoting Grothar:
With Convergence




that is why I think a new center will form under the convection
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Quoting reedzone:


Tropical Storm Lee was fully Tropical.. I don't understand why many on here are denying that.. Look it up. Formed form a TROPICAL wave, became TROPICAL Depression, then a TROPICAL Storm. It may have had the look of a Subtropical Storm, but Lee was fully Tropical.


Maybe I need to look at wiki before I post stuff like this..

By September 3, the storm sustained a large radius of maximum winds within the still elongated circulation; this unusual structure to purely tropical cyclones, combined with an overall hybrid appearance on satellite images, suggested Lee transitioned into a subtropical storm as it approached the Louisiana coast, similar to the transition of Tropical Storm Allison in 2001.[16]
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Some on here have such a desire for a storm in the gulf that it has cloulded their judgment. This system is a convoluted mess.
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1142. teammc
We have TS Debby
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1141. LargoFl
WEST CENTRAL FLORIDA

CITY SKY/WX TMP DP RH WIND PRES REMARKS
CRYSTAL RIVER FAIR 82 73 74 E6 29.95R
INVERNESS FAIR 82 72 69 S8 29.97R
BROOKSVILLE CLOUDY 82 73 74 SE6 29.96R
CLEARWATER CLOUDY 80 73 79 SE13G21 29.94S
TAMPA INTL CLOUDY 80 73 79 VRB7 29.96R
TAMPA EXEC DRIZZLE 81 73 78 SE8 29.96R
PLANT CITY CLOUDY 82 75 78 SE7 29.98R
MACDILL AFB DRIZZLE 79 77 94 SE12 29.95R
PETER O KNIGHT DRIZZLE 79 72 78 SE8 29.96R
ST PETERSBURG LGT RAIN 80 75 84 S16 29.93R
SARASOTA LGT RAIN 78 75 90 SE10 29.94R
VENICE RAIN 77 75 94 SE6 29.95S
Member Since: August 6, 2011 Posts: 4 Comments: 39052
1140. Patrap
Quoting bigwes6844:
well Pat me and you are about to go under a tropical strom warning at 4pm ct


I know, I was on the Loop.

Thanx
Member Since: July 3, 2005 Posts: 426 Comments: 128621
1139. Grothar
With Convergence


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Quoting reedzone:


Tropical Storm Lee was fully Tropical.. I don't understand why many on here are denying that.. Look it up. Formed form a TROPICAL wave, became TROPICAL Depression, then a TROPICAL Storm. It may have had the look of a Subtropical Storm, but Lee was fully Tropical.


Well after post season analysis the NHC saw that it made landfall as a sub-tropical system.
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Quoting Dakster:
Will the people of NOLA take it serious this time around?



No

Bourbon is prolly rockin right now
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well Pat me and you are about to go under a tropical strom warning at 4pm ct
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1135. Patrap
Quoting Dakster:
Will the people of NOLA take it serious this time around?



Certainlty,as in Gustav..2008.

No one hardly stayed,plus this aint August neither.
Member Since: July 3, 2005 Posts: 426 Comments: 128621
Or as Johnny Cash would say " I hear the train a coming."
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Recon Has Found West Winds renumber appears very likely within the hour BUT 96L is not well organized at this time to intensify quickly it will take a while to get going
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Oh, and I'm on the S.W. coast of Fl. and this storm doesn't worry me at all.
Right now the greatest threat is coastal flooding in La.
Member Since: September 16, 2007 Posts: 0 Comments: 7289
Hopefully, the folks having afternoon drinks at the FloraBama Lounge on the beachfront have the TV on...
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Quoting FSUCOOPman:


Don't listen to me, listen to NHC or official authorities, but I don't think this will be a high wind event, especially for the Tampa area.
I already put duct tape on all my windows
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1129. aquak9
Quoting flowrida:
I live in Tampa, I am getting really nervous. Should I go and buy some plywood to put over my windows?


concrete would be better
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1128. Patrap
18:38:30Z 25.933N 87.867W 974.2 mb
(~ 28.77 inHg) 250 meters
(~ 820 feet) 1002.3 mb
(~ 29.60 inHg) - From 68° at 12 knots
(From the ENE at ~ 13.8 mph) 23.0°C*
(~ 73.4°F*) 23.0°C*
(~ 73.4°F*) 14 knots
(~ 16.1 mph) 11 knots*
(~ 12.6 mph*) 4 mm/hr*
(~ 0.16 in/hr*) 9.4 knots* (~ 10.8 mph*)
78.6%*
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 18:29:00Z (first observation), the observation was 304 miles (489 km) to the S (184°) from Pensacola, FL, USA.

At 18:38:30Z (last observation), the observation was 310 miles (499 km) to the SSE (154°) from New Orleans, LA, USA.
Member Since: July 3, 2005 Posts: 426 Comments: 128621
1127. rxse7en
Quoting WxGeekVA:
It would appear that the smaller vorticies are rotating around a broader, weaker low...

Mini-Fujiwara system.
Member Since: August 21, 2005 Posts: 0 Comments: 530
Quoting flowrida:
I live in Tampa, I am getting really nervous. Should I go and buy some plywood to put over my windows?


If I was in Tampa I wouldn't be worried. If the storm does move towards Fl. it would be weaker.

A slow moving westward moving storm would have a better chance of strengthening. Even then, the conditions are not the best.
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1125. Dakster
Will the people of NOLA take it serious this time around?

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Well I'll forecast one thing for sure today. Jedkins will no longer be worried about Fl. rainfall after tonight. Look at the Key West radar OMG.
Member Since: August 18, 2008 Posts: 0 Comments: 3113
Quoting flowrida:
I live in Tampa, I am getting really nervous. Should I go and buy some plywood to put over my windows?


Don't listen to me, listen to NHC or official authorities, but I don't think this will be a high wind event, especially for the Tampa area.
Member Since: August 29, 2008 Posts: 0 Comments: 376
Quoting reedzone:


Tropical Storm Lee was fully Tropical.. I don't understand why many on here are denying that.. Look it up. Formed form a TROPICAL wave, became TROPICAL Depression, then a TROPICAL Storm. It may have had the look of a Subtropical Storm, but Lee was fully Tropical.

Lee transitioned into a subtropical storm at landfall.
Member Since: July 6, 2010 Posts: 113 Comments: 32250
Quoting flowrida:
I live in Tampa, I am getting really nervous. Should I go and buy some plywood to put over my windows?
NO , looks to be a Heavy Rain event with gusty winds now if w are talking about a hurricane thats a different story
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1120. Patrap
Quoting FSUCOOPman:


great graphic WxVA, agree...

that makes all of the wind barbs make sense, and a setup like that will continue to give the models fits!


No, the mean coc is well embedded in the Grids, its the Upper air steering that's giving the Models trouble on a consensus solution.
Member Since: July 3, 2005 Posts: 426 Comments: 128621
Quoting GeorgiaStormz:


2nd swirl?


Yeah, as usual the mid and low levels are not perfectly stacked.

All of this data is going in the models anyway, just sit tight, that's the whole point; to sample not just the CoC but any curious features in the environment, so the models have better fix and resolution.

I figure the 8pm outputs should be much more reliable than the jokes we've had so far.
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Quoting tropicfreak:
Like I said yesterday... this storm has similar characteristics to what Lee attained, 2 swirls, and a similar form (comma shape). Only difference is Lee was subtropical and obviously 96L isn't.


Tropical Storm Lee was fully Tropical.. I don't understand why many on here are denying that.. Look it up. Formed form a TROPICAL wave, became TROPICAL Depression, then a TROPICAL Storm. It may have had the look of a Subtropical Storm, but Lee was fully Tropical.
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Would not be surprised to see the center relocate further east as for TS Warnings i expect from Morgan City Louisiana to Indian Pass florida . i highly disagree with Hurricane watches At this time but everyone from louisiana to Central florida appear to be under the gun i dont see this moving west (IMO)
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Quoting bigwes6844:
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.


I agree. NHC has to go with what they've got. And the NHC has to worry about alarming people that don't need to be "alarmed."
The NHC has taken a some heat for some of its intensity forecasts over the past couple years.
Member Since: September 16, 2007 Posts: 0 Comments: 7289
Quoting stormpetrol:
Looks like HHs are finding multiple centers within a close area, maybe the center is relocating further East or just a very broad center.


Or multiple tstorms jahaha a jk
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Quoting WxGeekVA:
It would appear that the smaller vorticies are rotating around a broader, weaker low...



great graphic WxVA, agree...

that makes all of the wind barbs make sense, and a setup like that will continue to give the models fits!
Member Since: August 29, 2008 Posts: 0 Comments: 376
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


I have observed the same thing with people here when there is suddenly the possibility of a tropical storm on the way, I'm get all excited and most people have heard nothing about it, or do not care. In general, however, tropical storms are nothing to panic over or get too concerned about. For those in the path, just be prepared and if in a low-lying area, evacuate if advised to. This system, soon to be TS Debbie, will not be anything like Major Hurricane Katrina.

Also, looking at the main computer models, I would likely begin to discount the possibility of a Florida Peninsula landfall if it weren't for the GFS being so incredibly consistent with the path for the last few days, even as the other models have shuffled around on their projected paths.
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I live in Tampa, I am getting really nervous. Should I go and buy some plywood to put over my windows?
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Quoting RTSplayer:



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.
okay i see now. so heres my next question, since this storm is edgeing the coast of Florida with the rain how far do u expect the warnings to go if named at 5?
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1109. Patrap
Quoting spathy:


When they close those,are they also pumping water out?


Thats just standard procedure..NOLA has to close floodgates as well and that takes 8-12 Hours depending upon path
Member Since: July 3, 2005 Posts: 426 Comments: 128621
Quoting ncstorm:
144 hours out




That would actually be quite beneficial, especially if we could get a northern hook out of it after that position, would bring some much needed rain to all of the desert states.
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Quoting MAweatherboy1:

I think posting hurricane watches is risky at this point because of the lack of confidence in the track.


Agree. That is why I said they will probably make that call tomorrow morning depending on how she looks in the am and can do another set of models with fresher data all the way around.
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Quoting MiamiHurricanes09:
Quite the headache. The TVCN just has it wobbling around throughout the forecasting period.


That's not bad compared to this.
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1105. LBAR
I'm not sure how this storm goes west.
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Quoting MAweatherboy1:
Now I see confirmed west winds... Probably a renumber in about an hour and a half and then a 5PM advisory.


Debby is imminent....
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1103. Walshy
Quoting GeorgiaStormz:
i think we would have a bigger problem if the coc was under the convec


obvious is obvious
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1102. Patrap
18:15 Viz

Member Since: July 3, 2005 Posts: 426 Comments: 128621
Like I said yesterday... this storm has similar characteristics to what Lee attained, 2 swirls, and a similar form (comma shape). Only difference is Lee was subtropical and obviously 96L isn't.
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Now I see confirmed west winds... Probably a renumber in about an hour and a half and then a 5PM advisory.
Member Since: February 11, 2012 Posts: 83 Comments: 7833
Quoting Patrap:
Best take a deep breath first
Hi Pat,do you think the northern gulf is at risk?
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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.


To not know anything surprises me as well. It has been overcast and rainy in Florida for at least the past three days which is not typical of the normal Florida rainy season. Most people here on the Florida west coast know that mornings are clear blue skies with increasing cloudiness by the afternoon and thunderstorms in the late afternoon/evening. The last few days have been atypical and people here should know better than to let their guard down.
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It would appear that the smaller vorticies are rotating around a broader, weaker low...

Member Since: September 3, 2011 Posts: 13 Comments: 3474

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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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