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 MiamiHurricanes09:
I'm thinking a an extremely large cone moving into the Louisiana/Texas border. Peak intensity of 65kts.


What about the GFS?
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1445. LargoFl
REA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
309 PM EDT SAT JUN 23 2012

...CONTINUING TO MONITOR THE GULF...

.SHORT TERM (TONIGHT-MONDAY)...
FORECAST IS STILL HIGHLY DEPENDENT UPON THE POSSIBLE DEVELOPMENT
OF THE AREA OF LOW PRESSURE IN THE CENTRAL GULF OF MEXICO. MODELS
ARE STILL VERY CONSISTENT THROUGH SUNDAY LIFTING THE LOW NORTHWARD
INTO THE NORTHERN GULF. WITH THE CONVECTION DISPLACED TO THE
EAST...THIS WILL KEEP NUMEROUS TO WIDESPREAD SHOWERS AND A FEW
THUNDERSTORMS ACROSS THE AREA THROUGH SUNDAY. WINDS WILL BE
GENERALLY SE/S AND GUSTY...WHICH MAY CAUSE SOME MINOR COASTAL
FLOODING FROM TAMPA BAY NORTHWARD. WILL ISSUE A COASTAL FLOOD
ADVISORY FOR THIS. IN ADDITION...WITH WINDS OVER THE COASTAL
WATERS INCREASING AND SWELLS COMING IN FROM THE SW...WILL ALSO
RAISE A HIGH SURF ADVISORY AND HIGH RIP CURRENT RISK FOR AREA
BEACHES FROM PINELLAS SOUTH. THESE WILL BE IN EFFECT THROUGH
SUNDAY EVENING OR MONDAY MORNING. FOR SUNDAY NIGHT AND
MONDAY...THERE IS STILL A SPLIT IN THE MODELS BETWEEN THE EASTWARD
TRACK OF THE GFS...THE NORTHWARD TRACK OF THE CANADIAN AND THE
WESTWARD TRACK OF THE ECMWF. FOR NOW HAVE LEANED TOWARD THE
CANADIAN AND ECMWF...KEEPING THE SYSTEM WEST OF THE AREA WITH
MOISTURE LIFTING NORTH MONDAY ALLOWING FOR A LITTLE LESS SKY
COVER...THOUGH STILL MOSTLY CLOUDY...AND SLIGHTLY WARMER AFTERNOON
HIGHS GOING FROM THE MID 80S SUNDAY TO THE UPPER 80S MONDAY.

.LONG TERM (MONDAY NIGHT-SATURDAY)...
WITH ALL THE UNCERTAINTIES WITH RESPECT TO THE DISTURBANCE IN THE
GULF...I HAVE LOWER THAN NORMAL CONFIDENCE IN THE EXTENDED
FORECAST. THE GFS IS THE ONLY GLOBAL BRINGING THE DISTURBANCE
EASTWARD TOWARD FLORIDA. THE REMAINDER OF THE GUIDANCE TAKES THE
SYSTEM WESTWARD AWAY FROM THE STATE. WITH THIS IN MIND...BASICALLY
USED A BLEND OF THE CANADIAN AND ECMWF THROUGH THURSDAY AND JUST
THE ECMWF THROUGH SATURDAY.

FOR TUESDAY...DESPITE THE SYSTEM BEING WELL TO THE WEST...DEEP
SOUTHERLY FLOW CONTINUES TO BRING AMPLE MOISTURE FOR AT LEAST 50
PERCENT RAIN CHANCES...WITH THE MOST LIKELY TIMING BEING THE
AFTERNOON HOURS WITH HEATING.

BY WEDNESDAY...THE ATLANTIC SUB-TROPICAL RIDGE SHOULD BE BUILDING
BACK OVER THE REGION AS THE DISTURBANCE CONTINUES TO MOVE AWAY. AN
UPPER-LEVEL TROUGH WILL BE MOVING AWAY FROM THE EAST COAST
ALLOWING AN UPPER-LEVEL RIDGE TO BUILD NORTH OF THE STATE. THIS
WOULD BE MORE OF A TYPICAL SUMMER-TIME PATTERN RESULTING IN NEAR-
CLIMATOLOGICAL RAIN CHANCES ON WEDNESDAY WHICH WILL CONTINUE
THROUGH SATURDAY. THE MORNINGS SHOULD BE PARTLY CLOUDY AND MAINLY
DRY...FOLLOWED BY A 40 PERCENT CHANCE OF AFTERNOON SHOWERS AND
STORMS. THE EVENINGS WILL START OFF WITH ISOLATED STORMS...BUT FOR
THE MOST PART WILL BE DRY.
Member Since: August 6, 2011 Posts: 4 Comments: 38197
According to GREarth, those two eddies are rotating around a common center in-between.
Member Since: July 6, 2010 Posts: 113 Comments: 31917
1441. rxse7en
Quoting Altestic2012:
WOW! 2012 is officially on, now. We already have STORMTOP wishcasting Debby into NOLA! :-)
He's still around 'casting NOLA? I thought he was gone years ago. Where's Leftyy420 to set him straight?
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1440. Patrap
Quoting FLWeatherFreak91:
It's going to rotate back around into the convection.


Thats just the MEan center spitting out Vortices on the Down stroke or South side.

It will continue to do that until the CoC can sustain a Warm column.
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Is it spliting in two?

Link
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Quoting reedzone:
Latest frame of the visible is VERY interesting.. The little vortex spin we all thought could be the LLC, just collapsed... If i'm lookin at this right...



hmmm
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1437. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 38197
Quoting TropicalAnalystwx13:
Looks like recon is going into the convection.

Maybe they'll find some 50mph winds.
Member Since: February 11, 2012 Posts: 83 Comments: 7754
Quoting AllStar17:


I don't think it would collapse that fast.
It's going to rotate back around into the convection.
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Quoting TropicalAnalystwx13:
Looks like recon is going into the convection.


Good. I am very eager to see what they find in terms of winds there.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
I'm thinking a an extremely large cone moving into the Louisiana/Texas border. Peak intensity of 65kts.
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:)
Quoting TropicalAnalystwx13:
Looks like recon is going into the convection.
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Got to love wishcasters.... Irene only gave me 60 mph winds in North Carolina but it was scary. Tropical storm is to not be messed with.
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Quoting reedzone:
Latest frame of the visible is VERY interesting.. The little vortex spin we all thought could be the LLC, just collapsed... If i'm lookin at this right...



I don't think it would collapse that fast.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Looks like recon is going into the convection.
Member Since: July 6, 2010 Posts: 113 Comments: 31917
Quoting wunderweatherman123:
i had 13 since may 1st. im sticking with it despite the very fast start to the season

Remember, activity should slow down later in the season as El Nino sets in... Early season forecasts of 10-14 storms are still on track.
Member Since: February 11, 2012 Posts: 83 Comments: 7754
2pm update has most things headed to texas but then turn to the NE and head through LA
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Debby is in the building. ;)
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Quoting VAbeachhurricanes:
Why a TS? I dont see any HH obs that have 40 mph winds


I did see a 46mph observation a while back.
Member Since: September 16, 2007 Posts: 0 Comments: 6646
Latest frame of the visible is VERY interesting.. The little vortex spin we all thought could be the LLC, just collapsed... If i'm lookin at this right...

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URNT12 KNHC 231927
VORTEX DATA MESSAGE AL962012
A. 23/18:37:40Z
B. 25 deg 54 min N
087 deg 50 min W
C. NA
D. 15 kt
E. 063 deg 14 nm
F. 165 deg 17 kt
G. 065 deg 73 nm
H. EXTRAP 1002 mb
I. 24 C / 340 m
J. 24 C / 338 m
K. 24 C / NA
L. NA
M. NA
N. 134 / 1
O. 0.02 / 5 nm
P. AF302 01AAA INVEST OB 07
MAX FL WIND 17 KT NE QUAD 18:11:00Z
MAX OUTBOUND FL WIND 26 KT SW QUAD 18:52:00Z
SLP EXTRAP FROM BELOW 1500 FT
PEAK SFC WND 32KTS NW QUAD AT 17:08:20Z
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1420. nigel20
Quoting CybrTeddy:


IMO - 12-13 named.

Agreed.
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Sticking with 15 named storms.Looks like that is going to come true.
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1418. LargoFl
Member Since: August 6, 2011 Posts: 4 Comments: 38197
Also, if the center of Debby is indeed completing a mini-loop, it should get quite a bit closer to the convection on the east side.
Member Since: June 29, 2009 Posts: 13 Comments: 5313
Quoting CybrTeddy:


IMO - 12-13 named.
i had 13 since may 1st. im sticking with it despite the very fast start to the season
Member Since: August 23, 2011 Posts: 0 Comments: 1601
Quoting Gorty:
I really have no idea where her center is. Can someone give an approx. in miles not in lat./long?


It's about 360 miles WSW of Tampa.
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1414. rxse7en
COC seem to be at 87N26W and still tracking NNE?
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Center location
308 statue miles (495 km) to the S (184°) from Pensacola, FL, USA.
Member Since: September 16, 2007 Posts: 0 Comments: 6646
1412. Patrap
19:28:30Z 24.950N 86.950W 973.3 mb

(~ 28.74 inHg) 278 meters
(~ 912 feet) 1004.5 mb
(~ 29.66 inHg) - From 228° at 33 knots
(From the SW at ~ 37.9 mph) 24.0°C
(~ 75.2°F) 22.5°C
(~ 72.5°F) 34 knots
(~ 39.1 mph) 25 knots
(~ 28.7 mph) 2 mm/hr
(~ 0.08 in/hr) 24.3 knots (~ 27.9 mph)
73.5%

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 19:19:00Z (first observation), the observation was 376 miles (604 km) to the W (274°) from Key West, FL, USA.

At 19:28:30Z (last observation), the observation was 326 miles (524 km) to the W (275°) from Key West, FL, USA.
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Quoting nigel20:

2009 had a very slow start...i think with this early and pretty active start, we should surpass 2009.


IMO - 12-13 named.
Member Since: July 8, 2005 Posts: 259 Comments: 23923
debby.will.go.up.the.riogrande.valley.beginning.the .moonsoon.season.in.sw.usa
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Why a TS? I dont see any HH obs that have 40 mph winds
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Quoting Sfloridacat5:


From Tropical Atlantic's site.
26.0N 87.6W


Sorry, use the sat map on NHC to locate the center on a map. That's what I do.
Member Since: September 16, 2007 Posts: 0 Comments: 6646
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Go back to home depot tomorrow when they get about 50 truckloads of plywood, and then see what they recommend.
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Will Debby get to do Dallas again ? Or will she head for FL or the central Gulfcoast. Time to break out the Fresca
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1404. GHOSTY1
Quoting weatherlover94:


yea Heaven forbid this should not blow up into a monster and destroy Texas....weird people these days

I see how that can be taken too far, i didnt mean some catastrophic explosion of convection but enough that we can start gettin some rain on all quads, so more rain for more areas, if it heads toward Texas. Anyways if it happens it happens, and vice versa. Relax...
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1403. Patrap
Pull up any NOAA FLoater Loop on Debby,and one can click the Menu Box, FRONTS, MSLP for the CoC..or "center"

Gulf Of Mexico - False Color RGB Loop
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My thinking: Cat 1 hurricane into Galveston... I'm pretty sold on a west track at this point, and as long as shear comes down a little Debby can become a hurricane... After all it's at 45mph already and has 3-4 days to strengthen.
Member Since: February 11, 2012 Posts: 83 Comments: 7754
1401. nigel20
Quoting Neapolitan:
Yowza:

2012

2009 had a very slow start...i think with this early and pretty active start, we should surpass 2009.
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I just got back from work. Looks like I couldn't have had better timing!
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Latest frame of the visible is VERY interesting.. The little vortex spin we all thought could be the LLC, just collapsed... If i'm lookin at this right...

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Since we have Debby, should we see a special advisory or will the NHC wait until 5:00pm EDT/4pm CDT?
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It's pretty awesome to see a cyclonic loop.
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Thunderstorms seem to be beginning to fire south of the circulation of Debby.
Member Since: June 29, 2009 Posts: 13 Comments: 5313

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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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