Gulf Distubance 91L More Organized, Headed Towards Florida

By: Dr. Jeff Masters , 5:21 PM GMT on June 05, 2013

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Tropical disturbance 91L in the Southeast Gulf of Mexico has gotten more organized over the past day, and the Hurricane Hunters are scheduled to fly their first mission of 2013 this afternoon to see if the storm is becoming a tropical depression. Buoy 42003 near the heaviest thunderstorms of 91L measured sustained winds of 33 mph, gusting to 41 mph this morning at 2 am EDT. Satellite loops show a lopsided storm, with a large area of heavy thunderstorms on the east side of a center of circulation that is trying to develop at the edge of a region of dry air that covers the entire Central and Western Gulf of Mexico. This dry air is due to a trough of low pressure whose upper level winds are also creating moderate wind shear of 15 - 20 knots. Wind shear is forecast to rise to the high range, by Thursday, and 91L is forecast to make landfall along the northern Gulf Coast of Florida on Thursday evening, so the system has a short window of time to intensify. NHC is giving the disturbance a 50% chance of developing into a tropical cyclone. I put these odds higher, at 60%. If it does develop, it will be difficult for 91L to get any stronger than a 45 mph tropical storm in the Gulf of Mexico. Regardless of whether or not 91L develops into a tropical depression, heavy rains will be the storm's main threat. A swath from Florida to New England can expect 2 - 4" of rain. A few isolated EF-0 tornadoes will also be possible along the northern Florida Gulf Coast. A storm surge of 1 - 3 feet is predicted for Cedar Key, Florida, and rip currents will be a risk for swimmers who brave the high surf. Fort Pickens, located in Gulf Islands National Seashore on a barrier island offshore from Pensacola, Florida, has been closed to visitors due to the approaching storm. A single 2-lane road vulnerable to storm surges runs to Fort Pickens. Officials want to prevent a repeat of the situation that occurred in September 2011, when Tropical Storm Lee pushed a storm surge over the road that blocked it with sand and debris, trapping numerous campers and visitors in Fort Pickens.

The storm is getting caught up in a trough of low pressure that will pull it quickly to the north-northeast beginning on Thursday, with the center expected to move over coastal North Carolina on Friday afternoon, and over Massachusetts on Friday night. If 91L does manage to become a tropical storm before making landfall on Thursday, it will quickly degenerate into a regular extratropical low pressure system before moving up the East Coast.


Figure 1. Latest satellite image of Invest 91L.


Figure 2. Predicted precipitation for the 7-day period ending June 12, 2013 from the NWS/NCEP. A swath of 2 - 4" of rain is expected from Florida to New England from 91L.

Jeff Masters

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Quoting GeorgiaStormz:
RPM still west should shift way east as well
Hello if I may ask what is the RPM (related to rain fall?),Thank you!!.
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Quoting Ameister12:
Happy Birthday to Ricki and Nigel! Have a great one!


Having a great time tracking 91L which should be upgraded if this pass verifies.
Member Since: May 28, 2013 Posts: 0 Comments: 303
529. 7544
Quoting Seflhurricane:
if recon confirms that we have TS Andrea expect Tropical storm warnigs for much of the west coast of florida likely from fort myers to just north of cedar key,fl
what about the east coast? tia just asking
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I expect a TS at 5 PM or 11 PM
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happy to see everyone is back
Member Since: July 14, 2009 Posts: 0 Comments: 2990
Quoting MissUnderstood:
Could anyone please explain the possible impact on the north Orlando area? TIA.


A lot of rain and threat for tornadoes. Winds could be breezy to Windy... depending on the strength of it.

Like always check the MLB NWS page for the official words on effects and such.
Member Since: August 14, 2008 Posts: 4 Comments: 4881
rain, some wind, more rain, possible weak tornados , check your local news
Quoting MissUnderstood:
Could anyone please explain the possible impact on the north Orlando area? TIA.
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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
305 PM EDT WED JUN 5 2013

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
SHORT TERM GUIDANCE STARTS OFF IN REASONABLE AGREEMENT WITH WIDE
UPPER TROUGH DOMINATING THE AREA...AND OF COURSE THE LOW IN THE GULF
OF MEXICO. THIS LOW IS PROGGED TO LIFT NORTHEAST AND PHASE WITH THE
MAIN UPPER TROUGH AS A SURFACE FRONT ASSOCIATED WITH THE LATTER
SYSTEM PUSHES INTO THE SOUTHEAST. AS WE MOVE THROUGH TODAY INTO
TOMORROW...THE NAM IS A LITTLE SLOWER AND SHARPER WITH THE UPPER
TROUGH.
..WHICH ALLOWS THE GULF LOW TO LIFT NORTH TO NORTH-NORTHWEST
AND INTENSIFY...MAKING LANDFALL IN THE WESTERN FLORIDA PANHANDLE
LATE ON THURSDAY. THIS SOLUTION HOWEVER IS NOT AT ALL SUPPORTED BY
THE OTHER GLOBAL MODELS...AND THE NAM IS THUS NOT BEING CONSIDERED
FOR THIS PACKAGE ESPECIALLY AFTER 06Z TONIGHT. THE PROBLEM IS THAT
MANY HI-RES MODELS...INCLUDING OUR LOCAL WRF AND THE SREF...USE NAM
MEMBERS AND THUS ALSO MUST BE THROWN OUT
. THE GFS IS ON THE FAST
SIDE OF THE ENVELOPE...ZIPPING THE GULF LOW NORTHEAST ACROSS NORTH
FLORIDA AND SOUTHEAST GEORGIA AND INTENSIFYING IT NEAR CHARLESTON
SOUTH CAROLINA BY 06Z FRIDAY /AT THE SAME TIME THAT THE NAM IS STILL
PUSHING THE SYSTEM ONSHORE NEAR FORT WALTON BEACH FLORIDA/. SO...HAD
TO GO WITH MAINLY THE ECMWF WITH SOME GFS MIXED IN. DID INCORPORATE
HRRR AND LOCAL WRF REFLECTIVITY
FIELDS INTO THE POP/WX GRIDS FOR
TONIGHT AS THESE SEEM TO BE CAPTURING ONGOING CONVECTION VERY
WELL...BUT AS MENTIONED ABOVE BEYOND 06Z TONIGHT HAD TO REMOVE LOCAL
WRF FROM CONSIDERATION.


SO...ALL THAT SAID...LOOKS LIKE THE GULF LOW WILL BE LIFTING
NORTHEAST AND BRINGING WIDESPREAD HEAVY RAIN TO PORTIONS OF NORTH
FLORIDA AND SOUTHEAST GEORGIA
. IN THE MEANTIME...CONVECTION AHEAD OF
TE APPROACHING FRONT WILL BE MOVING THROUGH THE TENNESSEE VALLEY
TONIGHT AND TOMORROW. HAVE PRETTY HIGH POPS SOUTH CENTRAL AND
NORTHWEST TONIGHT TO ACCOUNT FOR THIS...AND DEPENDING ON HOW FAR
INTO THE STATE THE PRE-FRONTAL CONVECTION GETS TONIGHT...MAY HAVE TO
INCREASE POPS ACROSS THE METRO AREA BUT FOR NOW KEPT THE METRO AT
HIGH CHANCE POPS. SBCAPES ACROSS THE AREA HAVE INCREASED TO BETWEEN
1000-2000 J/KG...THE ONLY REASON THEY ARE NOT HIGHER IS THAT CLOUDS
HAVE KEPT TEMPS DOWN THIS MORNING AND EARLY AFTERNOON BUT WITH A
SCATTERING TREND IN CLOUD COVER...INSTABILITY WILL CONTINUE TO
INCREASE. MODIFIED 12Z KFFC SOUNDING HAD AROUND 2500 J/KG FOR THIS
AFTERNOON. THAT SAID...AND WITH THE SUPPORT OF THE FRONT...CANNOT
RULE OUT A FEW STRONG TO AN ISOLATED SEVERE STORM ESPECIALLY IN
NORTHWEST GEORGIA. HEAVY RAIN AND LIGHTNING REMAIN THREATS AS WELL.

FOR THURSDAY...AS THE TWO MAIN FEATURES INTERACT /APPROACHING
FRONT AND GULF LOW/...HAVE INCREASED POPS TO LIKELY OR CATEGORICAL
AREA-WIDE. QPF VALUES REMAIN BELOW 2 INCHES FOR THE DURATION OF
THE EVENT SO AT THIS TIME AM NOT CONSIDERING ANY FLOOD WATCH
PRODUCTS... THOUGH OF COURSE AS NEW GUIDANCE COMES IN THIS WILL
HAVE TO BE REEVALUATED /ESPECIALLY IF THE NAM EVER CATCHES UP/. AS
FAR AS SEVERE POTENTIAL...IT WILL REALLY DEPEND ON THE EVENTUAL
TRACK OF THE LOW BUT THE SITUATION FOR TOMORROW DOES NOT LOOK VERY
IMPRESSIVE EXCEPT AGAIN IN NORTHWEST GEORGIA WHERE SOME CLEARING
MAY OCCUR EARLIER IN THE DAY TO ALLOW INSTABILITY TO RISE. EVEN
THEN...ONLY ISOLATED SEVERE AT BEST AT LEAST FOR NOW. AS WITH THIS
EVENING...THE ENTIRE AREA IS IN A GENERAL THUNDER CATEGORY ON SPC
DAY2 OUTLOOK.
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Thanks for all the birthday wishes...i really appreciate it.
Member Since: November 6, 2010 Posts: 9 Comments: 7435
Quoting MiamiHurricanes09:
I've never understood why a high rain rate translates to suspect data. Wouldn't you expect to find the strongest winds in a strong thunderstorm lol?


The lower flight level winds makes it suspect as well.
Member Since: July 8, 2005 Posts: 259 Comments: 23011
Quoting CybrTeddy:
62mph on SFMR, however it was recorded in high rain-rates, which makes it suspect.
I've never understood why a high rain rate translates to suspect data. Wouldn't you expect to find the strongest winds in a strong thunderstorm lol?
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Quoting cg2916:
You can really see the center jump east:



That is a significant jump! Looks like I will be getting a little more than previously thought. Also looks like the new COC is trying to wrap convection.
Member Since: October 29, 2010 Posts: 0 Comments: 166
Could anyone please explain the possible impact on the north Orlando area? TIA.
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if recon confirms that we have TS Andrea expect Tropical storm warnigs for much of the west coast of florida likely from fort myers to just north of cedar key,fl
Member Since: July 14, 2009 Posts: 0 Comments: 2990
Hi nigel.Happy birthday and have many more.
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51.8 knots (~ 59.6 mph)
Tropical Storm


tropical storm winds
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Happy Birthday to Ricki and Nigel! Have a great one, guys!
Member Since: August 9, 2009 Posts: 10 Comments: 4498
Quoting 7544:
is it moving ne or east at this hour? tia interesting system


Its moving NE at the moment might make landfall near Tampa.
Member Since: May 28, 2013 Posts: 0 Comments: 303
Quoting allancalderini:
Happy Birthday Nigel hope you have a blast today and have fun with your family friends and the wunderground community.

Thanks Allan..very much appreciated!
Member Since: November 6, 2010 Posts: 9 Comments: 7435
Quoting popartpete:
I know this isn't going to be Sandy, but what are the chances of my hometown, Seaside Heights, NJ, getting walloped by a hurricane in October, and getting a tropical rainstorm in June? People are already freaking out. We've had enough tropical weather for a lifetime.

We won't know until later in June and October.... We can guess but you really can't make a solid prediction for October from early June... ESPECIALLY regarding hurricane landfalls
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You can really see the center jump east:

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Quoting Ricki13th:


Happy Birthday Man, two Geminis Lol

Same to you!
Member Since: November 6, 2010 Posts: 9 Comments: 7435
After this pass, NHC might have a 5PM advisory if a close circulation is validated.
Member Since: August 14, 2008 Posts: 4 Comments: 4881
Quoting nigel20:

Today is my birthday as well.


Happy Birthday Man, two Geminis Lol
Member Since: May 28, 2013 Posts: 0 Comments: 303
I know this isn't going to be Sandy, but what are the chances of my hometown, Seaside Heights, NJ, getting walloped by a hurricane in October, and getting a tropical rainstorm in June? People are already freaking out. We've had enough tropical weather for a lifetime.
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Quoting cg2916:
Unflagged 53kt/60 mph surface winds???

194900 2547N 08538W 9704 00328 0081 +200 +200 135043 044 053 034 00

Flight level winds were only at 50mph, though. Seems like a suspect reading.
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Either way, expect an increase in probabilities (%) at the next TWO.
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Quoting cg2916:
Unflagged 53kt/60 mph surface winds???

194900 2547N 08538W 9704 00328 0081 +200 +200 135043 044 053 034 00

Likely suspect due to a high rain rate. I believe anything over 0.75 inches per hour or so is generally suspect.
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I'd put the wind speed at around 35 or 40 kts, all the high winds come during heavy rain.

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Quoting Saltydogbwi1:
ime: 19:49:00Z
Coordinates: 25.7833N 85.6333W
Acft. Static Air Press: 970.4 mb (~ 28.66 inHg)
Acft. Geopotential Hgt: 328 meters (~ 1,076 feet)
Extrap. Sfc. Press: 1008.1 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 135° at 43 knots (From the SE at ~ 49.4 mph)
Air Temp: 20.0°C (~ 68.0°F)
Dew Pt: 20.0°C (~ 68.0°F)
Peak (10s) Flt. Lvl. Wind: 44 knots (~ 50.6 mph)
SFMR Peak (10s) Sfc. Wind: 53 knots (~ 60.9 mph)
SFMR Rain Rate: 34 mm/hr (~ 1.34 in/hr)
Probably an err, flight level finds don't support it.
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499. 7544
is it moving ne or east at this hour? tia interesting system
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Quoting cg2916:
Unflagged 53kt/60 mph surface winds???

194900 2547N 08538W 9704 00328 0081 +200 +200 135043 044 053 034 00

Very high rain rate.
Member Since: July 6, 2010 Posts: 108 Comments: 30241
Quoting nigel20:

Today is my birthday as well.
Happy Birthday Nigel hope you have a blast today and have fun with your family friends and the wunderground community.
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Quoting allancalderini:
HBD hope you have an awesome birthday.


Thanks alot man. This whole kinda ruin my plans here in Naples. Lol
Member Since: May 28, 2013 Posts: 0 Comments: 303
Quoting allancalderini:
HBD hope you have an awesome birthday.

Today is my birthday as well.
Member Since: November 6, 2010 Posts: 9 Comments: 7435
.
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ime: 19:49:00Z
Coordinates: 25.7833N 85.6333W
Acft. Static Air Press: 970.4 mb (~ 28.66 inHg)
Acft. Geopotential Hgt: 328 meters (~ 1,076 feet)
Extrap. Sfc. Press: 1008.1 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 135° at 43 knots (From the SE at ~ 49.4 mph)
Air Temp: 20.0°C (~ 68.0°F)
Dew Pt: 20.0°C (~ 68.0°F)
Peak (10s) Flt. Lvl. Wind: 44 knots (~ 50.6 mph)
SFMR Peak (10s) Sfc. Wind: 53 knots (~ 60.9 mph)
SFMR Rain Rate: 34 mm/hr (~ 1.34 in/hr)
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I don't think this low is closed yet, but another pass around may prove me wrong.
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62mph on SFMR, however it was recorded in high rain-rates, which makes it suspect.
Member Since: July 8, 2005 Posts: 259 Comments: 23011
Might be me but it looks like on sat image that it is trying to wrap the convection around the center finally.
Member Since: October 29, 2010 Posts: 0 Comments: 166
Quoting GeorgiaStormz:
What we're seeing is likely the beginning of the split the GFS showed....CMC has it now....ecmwf shows it but rapidly consolidates the second low & takes it inland



That will not happen until tomorrow!! afternoon
Member Since: June 20, 2012 Posts: 0 Comments: 2130
Quoting nrtiwlnvragn:
Updated coords, wind

AL, 91, 2013060518, , BEST, 0, 253N, 866W, 35, 1006, DB,
Will be going straight to Andrea if classified.
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RPM still west should shift way east as well
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by the looks of it we may have TS Andrea
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Updated coords, wind

AL, 91, 2013060518, , BEST, 0, 253N, 866W, 35, 1006, DB,
Member Since: September 23, 2005 Posts: 13 Comments: 10458
Quoting DataNerd:



Except the Low is open.


Too early to make that claim based on a single pass, it's going to be several passes I'm guessing before we get a definitive answer, always is.
Member Since: July 8, 2005 Posts: 259 Comments: 23011
Quoting DataNerd:



Except the Low is open.

It may or may not be. Enough of the circulation has not yet been sampled.
Member Since: July 6, 2010 Posts: 108 Comments: 30241
Quoting DataNerd:


Huh. Confusing little bugger is still open. Going to wait and see what the next pass around reveals but it certainly looks to be an open low to that southwest quadrant still.


Meaning not a TD yet.


Oh well... Maybe later.

I was hoping for a special tropical disturbance statement.
Member Since: March 10, 2006 Posts: 0 Comments: 9672
Quoting CybrTeddy:
45mph SFC winds, 54mph at flight level.
Quoting stormpetrol:
Time: 19:42:30Z
Coordinates: 25.4833N 85.8333W
Acft. Static Air Press: 971.4 mb (~ 28.69 inHg)
Acft. Geopotential Hgt: 306 meters (~ 1,004 feet)
Extrap. Sfc. Press: 1006.4 mb (~ 29.72 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 122° at 45 knots (From the ESE at ~ 51.7 mph)
Air Temp: 21.1°C (~ 70.0°F)
Dew Pt: 21.1°C (~ 70.0°F)
Peak (10s) Flt. Lvl. Wind: 47 knots (~ 54.0 mph)
SFMR Peak (10s) Sfc. Wind: 39 knots (~ 44.8 mph)
SFMR Rain Rate: 15 mm/hr (~ 0.59 in/hr)
(*) Denotes suspect data

I expect 91L to be upgraded to a Tropical Storm at 5pm est.



Except the Low is open.
Member Since: June 24, 2012 Posts: 0 Comments: 1534

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.