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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How fast do H.H. fly?
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Rise of the drones!

Tiny Airplanes and Subs Could Be Next Hurricane Hunters
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Quoting Ricki13th:
Florida is going to get soaked. Starting Tonight and into Friday. I'm not seeing too much in rain for Northern Florida and the panhandle. It consolidated and moved east where the convection was. Now trying to wrap up and tightening up.

You see the center shifting or relocating under the deeper convection...?
Member Since: April 16, 2013 Posts: 27 Comments: 3168
Latest reconn:

Time: 20:15:30Z
Coordinates: 26.0N 87.0167W
Acft. Static Air Press: 987.8 mb (~ 29.17 inHg)
Acft. Geopotential Hgt: 178 meters (~ 584 feet)
Extrap. Sfc. Press: 1008.1 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 79° at 32 knots (From the ENE/E at ~ 36.8 mph)
Air Temp: 22.9°C (~ 73.2°F)
Dew Pt: 20.9°C (~ 69.6°F)
Peak (10s) Flt. Lvl. Wind: 34 knots (~ 39.1 mph)
SFMR Peak (10s) Sfc. Wind: 33 knots* (~ 37.9 mph*)
SFMR Rain Rate: 2 mm/hr* (~ 0.08 in/hr*


2. 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
20:06:00Z 25.950N 86.367W 988.0 mb
(~ 29.18 inHg) 170 meters
(~ 558 feet) 1007.4 mb
(~ 29.75 inHg) - From 91° at 41 knots
(From the E at ~ 47.1 mph) 21.6°C
(~ 70.9°F) 20.8°C
(~ 69.4°F) 42 knots
(~ 48.3 mph) 36 knots*
(~ 41.4 mph*) 6 mm/hr*
(~ 0.24 in/hr*) 35.1 knots* (~ 40.4 mph*)
Tropical Storm* 85.7%*
20:06:30Z 25.950N 86.383W 987.4 mb
(~ 29.16 inHg) 171 meters
(~ 561 feet) 1007.2 mb
(~ 29.74 inHg) - From 92° at 44 knots
(From the E at ~ 50.6 mph) 22.2°C
(~ 72.0°F) 20.4°C
(~ 68.7°F) 45 knots
(~ 51.7 mph) 33 knots*
(~ 37.9 mph*) 4 mm/hr*
(~ 0.16 in/hr*) 32.3 knots* (~ 37.1 mph*)
73.3%*
20:07:00Z 25.950N 86.433W 987.7 mb
(~ 29.17 inHg) 169 meters
(~ 554 feet) 1006.8 mb
(~ 29.73 inHg) - From 92° at 43 knots
(From the E at ~ 49.4 mph) 22.4°C
(~ 72.3°F) 20.2°C
(~ 68.4°F) 45 knots
(~ 51.7 mph) 39 knots
(~ 44.8 mph) 1 mm/hr
(~ 0.04 in/hr) 37.3 knots (~ 42.9 mph)
Tropical Storm 86.7%
Member Since: June 24, 2012 Posts: 0 Comments: 1546
Florida is going to get soaked. Starting Tonight and into Friday. I'm not seeing too much in rain for Northern Florida and the panhandle. It consolidated and moved east where the convection was. Now trying to wrap up and tightening up.
Member Since: May 28, 2013 Posts: 0 Comments: 407
I Have a feeling we will see a 60 mph Tropical storm before landfall Between Sarasota- cedar key area
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More high winds in the northern quadrant

Time: 20:07:00Z
Coordinates: 25.95N 86.4333W
Acft. Static Air Press: 987.7 mb (~ 29.17 inHg)
Acft. Geopotential Hgt: 169 meters (~ 554 feet)
Extrap. Sfc. Press: 1006.8 mb (~ 29.73 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 92° at 43 knots (From the E at ~ 49.4 mph)
Air Temp: 22.4°C (~ 72.3°F)
Dew Pt: 20.2°C (~ 68.4°F)
Peak (10s) Flt. Lvl. Wind: 45 knots (~ 51.7 mph)
SFMR Peak (10s) Sfc. Wind: 39 knots (~ 44.8 mph)
SFMR Rain Rate: 1 mm/hr (~ 0.04 in/hr)
Member Since: June 24, 2012 Posts: 0 Comments: 1546
Quoting Ricki13th:


Thanks alot man. This whole kinda ruin my plans here in Naples. Lol
Raining all day in Naples?
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Quoting Ricki13th:
This is seriously get better looking as new frames come in. Wow! Glad it took this long to get its act together or the CMC ghost hurricane might have came true. This is going to be one hell of a season.

Tell me about it.
Sarcasm flag: Off
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Forgive me as I know this hasn't officially been named yet...but she is one hell of a fighter. I mean look at that dry air column to her west. Incredible.

Member Since: April 16, 2013 Posts: 27 Comments: 3168
Quoting Gearsts:
Dmin
The Yucatan Channel is really feeding convection into 91L.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting Gearsts:
For this system TS or not means nothing with winds of 45 and heavy rain so people should still prepared the same named or not.

Agreed
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Quoting cg2916:


One heck of a DMIN. What's that convection burst down south doing there?
Warming over center
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Quoting Levi32:


Exactly, but it has to be considered if it's an extremely isolated incident. If you're flying a hurricane and get a 10-second SFMR gust 30mph higher than everything around it, it's probably not at all representative of the storm's intensity. You want at least a couple obs showing consistent values. It's also silly to consider SFMR data if it's significantly higher than the flight-level wind speed.
Quoting nrtiwlnvragn:


 Two reasonsfor this overestimation:
 Current Geophysical Model Function (GMF) tuned to weak precipitation
conditions
 Current rain absorption model over-predictsthe absorption due to rain
Thanks guys, appreciate it.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
566. SLU
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For this system TS or not means nothing with winds of 45 and heavy rain so people should still prepared the same named or not.
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So here in Bradenton(near Sarasota) the rain has started. The winds are calm right now but we are expected 5 plus inches of rain. Also they are saying a possibility of tornadoes tonight and tomorrow as system gets closer. Hope it does not ramp up too fast as it looks to be tracking more east now...

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Quoting Gearsts:
Dmin


One heck of a DMIN. What's that convection burst down south doing there?
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Dmin
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Recon now turning for second pass.

Standby folks we will know very very soon now.
Member Since: June 24, 2012 Posts: 0 Comments: 1546
If this is a TS, I'd put it at 45 mph, 1005 mb.
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91 has gotten much better organized today, looking good to maybe get minimal TS strength like Doc said. Rainy days ahead.
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Quoting DataNerd:
40+mph winds all through this thing

Time: 20:03:30Z
Coordinates: 26.0N 86.2167W
Acft. Static Air Press: 988.2 mb (~ 29.18 inHg)
Acft. Geopotential Hgt: 170 meters (~ 558 feet)
Extrap. Sfc. Press: 1007.8 mb (~ 29.76 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 97° at 34 knots (From the E at ~ 39.1 mph)
Air Temp: 21.7°C (~ 71.1°F)
Dew Pt: 21.2°C (~ 70.2°F)
Peak (10s) Flt. Lvl. Wind: 35 knots (~ 40.2 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 6 mm/hr (~ 0.24 in/hr)


Wind vectors still dont exactly support a closed low however


Its strengthen as it gets closer the coast. Very impressive system.
Member Since: May 28, 2013 Posts: 0 Comments: 407
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?


 Two reasonsfor this overestimation:
 Current Geophysical Model Function (GMF) tuned to weak precipitation
conditions
 Current rain absorption model over-predictsthe absorption due to rain
Member Since: September 23, 2005 Posts: 14 Comments: 11271
This is seriously get better looking as new frames come in. Wow! Glad it took this long to get its act together or the CMC ghost hurricane might have came true. This is going to be one hell of a season.
Member Since: May 28, 2013 Posts: 0 Comments: 407
554. Skyepony (Mod)
Recon has turned & aimed toward the farthest west looking possible center.
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Member Since: August 31, 2009 Posts: 0 Comments: 5628
40+mph winds all through this thing

Time: 20:03:30Z
Coordinates: 26.0N 86.2167W
Acft. Static Air Press: 988.2 mb (~ 29.18 inHg)
Acft. Geopotential Hgt: 170 meters (~ 558 feet)
Extrap. Sfc. Press: 1007.8 mb (~ 29.76 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 97° at 34 knots (From the E at ~ 39.1 mph)
Air Temp: 21.7°C (~ 71.1°F)
Dew Pt: 21.2°C (~ 70.2°F)
Peak (10s) Flt. Lvl. Wind: 35 knots (~ 40.2 mph)
SFMR Peak (10s) Sfc. Wind: 38 knots (~ 43.7 mph)
SFMR Rain Rate: 6 mm/hr (~ 0.24 in/hr)


Wind vectors still dont exactly support a closed low however
Member Since: June 24, 2012 Posts: 0 Comments: 1546
The center does seem to make a fair jog east. And hey y'all long time no talk, back for another season.
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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?


Exactly, but it has to be considered if it's an extremely isolated incident. If you're flying a hurricane and get a 10-second SFMR gust 30mph higher than everything around it, it's probably not at all representative of the storm's intensity. You want at least a couple obs showing consistent values. It's also silly to consider SFMR data if it's significantly higher than the flight-level wind speed.
Member Since: November 24, 2005 Posts: 635 Comments: 26684
Link


Circulation visible. Appears to be tightening it may be that it was open on the first pass and closes by the time they come around.
Member Since: June 24, 2012 Posts: 0 Comments: 1546
547. Skyepony (Mod)
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Quoting HurricaneHunterJoe:
Deepen to a 998 Cat 1 like the CMC said a week ago?.....wouldnt that be funny!


Lol with all this wind with this storm. The Tampa drought has been busted.
Member Since: May 28, 2013 Posts: 0 Comments: 407
Quoting fmhurricane2009:


Guess that "Puny sheared low pressure system" heard you. Looks very promising now.


I will give the NHC a grade of A+ on the timing of the HH Mission.......or they just got lucky?...lololol
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Highest non contaminated vector

Time: 19:48:30Z
Coordinates: 25.75N 85.6333W
Acft. Static Air Press: 970.4 mb (~ 28.66 inHg)
Acft. Geopotential Hgt: 328 meters (~ 1,076 feet)
Extrap. Sfc. Press: 1008.2 mb (~ 29.77 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 131° 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)
SFMR Peak (10s) Sfc. Wind: 42 knots (~ 48.3 mph)Peak (10s) Flt. Lvl. Wind: 46 knots (~ 52.9 mph)
SFMR Peak (10s) Sfc. Wind: 42 knots (~ 48.3 mph)
SFMR Rain Rate: 22 mm/hr (~ 0.87 in/hr)
Member Since: June 24, 2012 Posts: 0 Comments: 1546
Quoting yonzabam:


Well, there's a view that the high pressure region that steered Sandy into NJ was caused by an abnormal jet stream, and that this abnormal jet stream was, in turn caused by a warmer arctic, caused by global warming.

The warmer arctic is here to stay, so if the rest of that is correct, late season hurricanes veering east, instead of west, may become more common. My personal opinion is that there will be more hurricanes going into the NE late in the season, but Sandy merged with a nor'easter, boosting its energy. Hopefully, you'll just get regular tropical storms weakening in northern waters.

A much better detailed answer then mine :P
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You can clearly see the center in this image animation...

Member Since: April 16, 2013 Posts: 27 Comments: 3168
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.


Well, there's a view that the high pressure region that steered Sandy into NJ was caused by an abnormal jet stream, and that this abnormal jet stream was, in turn caused by a warmer arctic, caused by global warming.

The warmer arctic is here to stay, so if the rest of that is correct, late season hurricanes veering east, instead of west, may become more common. My personal opinion is that there will be more hurricanes going into the NE late in the season, but Sandy merged with a nor'easter, boosting its energy. Hopefully, you'll just get regular tropical storms weakening in northern waters.
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Quoting Ricki13th:


Not Likely Its ramping up as we speak headed for Tampa Bay. It will remain stacked until the trough brings shear down the road. bottom line it has time to deep some more.
Deepen to a 998 Cat 1 like the CMC said a week ago?.....wouldnt that be funny!
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Quoting 7544:


Nothing for the East Coast unless the storm makes it to the Atlantic alive and heads towards land
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Quoting MissUnderstood:
Could anyone please explain the possible impact on the north Orlando area? TIA.


Likely moderate to heavy rainfall and breezy. I'd guess that you end up with a couple inches of rain and 15 to 20 mph winds
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Very impressive winds even if its contaminated. Likely going to be Andrea.The Tampa Bay shield is cracking as we speak.
Member Since: May 28, 2013 Posts: 0 Comments: 407

Update via Facebook

GOES-13, at 75 degrees West, will return to GOES-East operations on Thursday, June 6, 2013, at approximately 1534 -1545 UTC (first image at 1545 UTC). Derived products from GOES-13 will begin immediately following the switchover.
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Latest correct HDOB (not the erroneous 62 mph one) supports TS winds.

19:56:00Z 26.000N 85.683W 971.3 mb
(~ 28.68 inHg) 328 meters
(~ 1,076 feet) 1009.2 mb
(~ 29.80 inHg) - From 123 at 31 knots
(From the ESE at ~ 35.6 mph) 20.3C
(~ 68.5F) 20.3C
(~ 68.5F) 38 knots
(~ 43.7 mph) 47 knots*
(~ 54.0 mph*) 33 mm/hr*
(~ 1.30 in/hr*) 38.3 knots* (~ 44.1 mph*)
Tropical Storm* 123.7%*
19:56:30Z 26.000N 85.717W 971.3 mb
(~ 28.68 inHg) 329 meters
(~ 1,079 feet) 1009.0 mb
(~ 29.80 inHg) - From 105 at 26 knots
(From the ESE at ~ 29.9 mph) 21.0C
(~ 69.8F) 21.0C
(~ 69.8F) 29 knots
(~ 33.3 mph) 58 knots
(~ 66.7 mph) 40 mm/hr
(~ 1.57 in/hr) 52.0 knots (~ 59.8 mph)
Tropical Storm 200.0%
19:57:00Z 26.000N 85.750W 968.7 mb
(~ 28.61 inHg) 351 meters
(~ 1,152 feet) 1009.0 mb

(~ 29.80 inHg) - From 106 at 38 knots
(From the ESE at ~ 43.7 mph) 20.3C
(~ 68.5F) 20.3C
(~ 68.5F) 40 knots
(~ 46.0 mph) 54 knots*
(~ 62.1 mph*) 28 mm/hr*
(~ 1.10 in/hr*) 51.3 knots* (~ 59.0 mph*)
Tropical Storm* 135.0%*
Member Since: June 24, 2012 Posts: 0 Comments: 1546
Quoting WxLogic:
After this pass, NHC might have a 5PM advisory if a close circulation is validated.

Yep.
Member Since: April 16, 2013 Posts: 27 Comments: 3168
Recon has turned now coming about for the second pass. Will verify whether low has closed up in the mean time on the south western quadrant.
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Quoting Ricki13th:


Having a great time tracking 91L which should be upgraded if this pass verifies.

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