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 Dakster:


I should have put my sarcasm: on field... It was a sarcastic response.

Which is why I then looked up the site with all the data on the plane. I was curious myself.


I see. Either way, there are always some around here who could use the random aircraft speed knowledge, ha.
Member Since: July 2, 2011 Posts: 0 Comments: 1183
20:26:00Z 25.850N 87.450W 873.8 mb
(~ 25.80 inHg) 1,243 meters
(~ 4,078 feet) 1007.9 mb
(~ 29.76 inHg) - From 74° at 32 knots
(From the ENE at ~ 36.8 mph) 18.7°C
(~ 65.7°F) 14.3°C
(~ 57.7°F) 32 knots
(~ 36.8 mph) 18 knots
(~ 20.7 mph) 0 mm/hr
(~ 0 in/hr) 18.0 knots (~ 20.7 mph)
56.2%
20:26:30Z 25.867N 87.483W 876.1 mb
(~ 25.87 inHg) 1,222 meters
(~ 4,009 feet) 1008.1 mb
(~ 29.77 inHg) - From 78° at 32 knots
(From the ENE at ~ 36.8 mph) 18.5°C
(~ 65.3°F) 15.0°C
(~ 59.0°F) 32 knots
(~ 36.8 mph) 21 knots
(~ 24.1 mph) 0 mm/hr
(~ 0 in/hr) 21.0 knots (~ 24.1 mph)
65.6%
Member Since: June 24, 2012 Posts: 0 Comments: 1546


Well. Now we just sit back and see if there is a VDM or not.
Member Since: June 24, 2012 Posts: 0 Comments: 1546


more for the visual viewer....
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Greetings all. Oh great. More rain.
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Quoting notanotherwrong:
so whats in store for daytona now on the east coast? they said earlier only 2 to 4 inches of rain and a little breezy tommorow will that now change if it hits tampa


We will see some Action in Southern Florida as there is moisture coming up from the Yucatan. Worse of the weather will be tonight and on Thursday. Some lingering effects on Friday. 1-4 inches seem about right but could be more though. Chance of some gust winds and POSSIBLY a weak tornado or two there is some shear over Florida the can spark couple here or there.

Member Since: May 28, 2013 Posts: 0 Comments: 405
Quoting OrchidGrower:
Can't speak for the rest of the gang, but here in Cape Coral I will be happy to see something close to the rainfall totals Dr. Masters posted for our coast. Breeze picked up a tad today and drizzle got more "insistent," but still waiting for the showers. I'm getting suspicious that the hard rains, when/if they come, will not hang around us for long! To me, it looks like the Low has begun to genuinely move.


Going to get those big rains tonight and tomorrow I believe. Waiting also.
Member Since: February 14, 2004 Posts: 2 Comments: 664
Quoting MAweatherboy1:

Agreed, it probably would have been renumbered by now if they were going to do a 5 PM advisory, and recon really hasn't found enough to confirm a tropical cyclone.

maybe I've seen very late renumbers before so its still possible
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Quoting Slamguitar:


Mostly depends on the type of speed we're talking about. Headwinds and tailwinds effect the ground speed (GS) but don't affect your true airspeed (TAS). You want to fly a certain TAS to get right amount of air flowing around your wings to achieve lift. Fly off of your GS indicator and bad things are sure to happen. We always use indicated (IAS) or true airspeed in aviation.


I should have put my sarcasm: on field... It was a sarcastic response.

Which is why I then looked up the site with all the data on the plane. I was curious myself.
Member Since: March 10, 2006 Posts: 0 Comments: 10414
Quoting MAweatherboy1:

Agreed, it probably would have been renumbered by now if they were going to do a 5 PM advisory, and recon really hasn't found enough to confirm a tropical cyclone.


they need more information before they would want to do so
Member Since: June 17, 2011 Posts: 11 Comments: 6539
Quoting CybrTeddy:
An advisory at 5pm seems unlikely.


They could issue a special advisory fairly close to there though. TS Edoward (sp. 2008) had an advisory 1 hour after 5PM
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Quoting CybrTeddy:
An advisory at 5pm seems unlikely.
Unless we see a VDM shortly...

I agree with no 5pm. Conditions at this time do not warrant an upgrade, IMO.
Member Since: June 14, 2006 Posts: 0 Comments: 2108
Quoting CybrTeddy:
An advisory at 5pm seems unlikely.

Agreed, it probably would have been renumbered by now if they were going to do a 5 PM advisory, and recon really hasn't found enough to confirm a tropical cyclone.
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Quoting CybrTeddy:
An advisory at 5pm seems unlikely.


If that is the case,a Special Advisory may be issued.
Member Since: Posts: Comments:
Can't speak for the rest of the gang, but here in Cape Coral I will be happy to see something close to the rainfall totals Dr. Masters posted for our coast. Breeze picked up a tad today and drizzle got more "insistent," but still waiting for the showers. I'm getting suspicious that the hard rains, when/if they come, will not hang around us for long! To me, it looks like the Low has begun to genuinely move.
Member Since: Posts: Comments:
Coming up on 5:00 PM looks like we'll have to wait for a special advisory.
Member Since: August 31, 2009 Posts: 0 Comments: 5628


For all off you visual people out there
Member Since: June 17, 2011 Posts: 11 Comments: 6539
An advisory at 5pm seems unlikely.
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Quoting DataNerd:
Looks like it may be closed low now

Time: 20:25:30Z
Coordinates: 25.85N 87.4167W
Acft. Static Air Press: 889.4 mb (~ 26.26 inHg)
Acft. Geopotential Hgt: 1,064 meters (~ 3,491 feet)
Extrap. Sfc. Press: 1005.6 mb (~ 29.70 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 74° at 32 knots (From the ENE at ~ 36.8 mph)
Air Temp: 19.7°C (~ 67.5°F)
Dew Pt: 14.8°C (~ 58.6°F)
Peak (10s) Flt. Lvl. Wind: 33 knots (~ 37.9 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -


Winds on either side of the last 40 minutes of the flight path back that up but another punch through the center will have to verify.


need to see a vortex message first
Member Since: September 19, 2005 Posts: 2 Comments: 4251
Flight level winds dropping off sharply. Getting close to coc.
Member Since: June 24, 2012 Posts: 0 Comments: 1546
Quoting Dakster:


Depends on whether they are fighting a head wind or tail wind.


Mostly depends on the type of speed we're talking about. Headwinds and tailwinds effect the ground speed (GS) but don't affect your true airspeed (TAS). You want to fly a certain TAS to get right amount of air flowing around your wings to achieve lift. Fly off of your GS indicator and bad things are sure to happen. We always use indicated (IAS) or true airspeed in aviation.
Member Since: July 2, 2011 Posts: 0 Comments: 1183
417 MPH is top speed...

Here is a good place for other facts.

http://www.hurricanehunters.com/plane.html

Link
Member Since: March 10, 2006 Posts: 0 Comments: 10414
Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 5th day of the month at 20:30Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 303)
Mission Purpose: Investigate first suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 09

Mandatory Data...

Observation Time: Wednesday, 20:30Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 25.9N 87.4W
Location: 314 miles (505 km) to the S (182°) from Pensacola, FL, USA.
Turbulence: Light
Conditions Along Flight Route: In the clear
Pressure Altitude: 210 meters
Flight Level Wind: From 80° at 24 knots (From the E at ~ 27.6 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 24°C
Flight Level Dew Point: 24°C
Weather (within 30 nautical miles): Shower(s) (continuous or intermittent precipitation - from cumuliform clouds)
Mean Sea Level Pressure (MSLP): 1008 mb (extrapolated)

Optional Data...

Estimated Surface Wind: From 60° at 25 knots (From the ENE at ~ 28.7 mph)

Remarks Section...

Surface Wind Speed (likely by SFMR): 24 knots (~ 27.6mph)
Member Since: June 24, 2012 Posts: 0 Comments: 1546

Quoting cg2916:


One heck of a DMIN. What's that convection burst down south doing there?
Ruining Cancun vacations no doubt

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Quoting notanotherwrong:
who said that i thought its now going to hit tampa?


Its making a beeline towards Tampa maybe a little further north but right around the Tampa area as it is moving along with the convection to the NE.
Member Since: May 28, 2013 Posts: 0 Comments: 405
603. VR46L
Some LSU Imagery

Loops embedded
IR Imagery



Low cloud
Member Since: Posts: Comments:
Quoting masonsnana:
DataNerd and others, Thank You for all your posts :)


no problem!
Member Since: June 24, 2012 Posts: 0 Comments: 1546
601. seminolesfan
8:34 PM GMT on June 05, 2013


Dry air entrainment and unrelenting shear are preventing any persistent organized convection.

Each time a LLC spins up, it gets spun out of the larger low pressure gyre because of the lack of persistent convection to maintain its energy.

Member Since: June 14, 2006 Posts: 0 Comments: 2108
600. DataNerd
8:34 PM GMT on June 05, 2013
Looks like it may be closed low now

Time: 20:25:30Z
Coordinates: 25.85N 87.4167W
Acft. Static Air Press: 889.4 mb (~ 26.26 inHg)
Acft. Geopotential Hgt: 1,064 meters (~ 3,491 feet)
Extrap. Sfc. Press: 1005.6 mb (~ 29.70 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 74° at 32 knots (From the ENE at ~ 36.8 mph)
Air Temp: 19.7°C (~ 67.5°F)
Dew Pt: 14.8°C (~ 58.6°F)
Peak (10s) Flt. Lvl. Wind: 33 knots (~ 37.9 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -


Winds on either side of the last 40 minutes of the flight path back that up but another punch through the center will have to verify.
Member Since: June 24, 2012 Posts: 0 Comments: 1546
599. masonsnana
8:34 PM GMT on June 05, 2013
DataNerd and others, Thank You for all your posts :)
Member Since: February 14, 2004 Posts: 2 Comments: 664
598. weatherh98
8:33 PM GMT on June 05, 2013


looking pretty darn good
Member Since: June 17, 2011 Posts: 11 Comments: 6539
597. DataNerd
8:33 PM GMT on June 05, 2013
Link


New thunderstorms starting to form over the center
Member Since: June 24, 2012 Posts: 0 Comments: 1546
595. Slamguitar
8:32 PM GMT on June 05, 2013
Quoting Autistic2:
How fast do H.H. fly?


Usually cruise around 350 KTS TAS from what I hear.
Member Since: July 2, 2011 Posts: 0 Comments: 1183
594. DataNerd
8:32 PM GMT on June 05, 2013
Heading in:
Member Since: June 24, 2012 Posts: 0 Comments: 1546
593. Dakster
8:31 PM GMT on June 05, 2013
Quoting Autistic2:
How fast do H.H. fly?


Depends on whether they are fighting a head wind or tail wind.
Member Since: March 10, 2006 Posts: 0 Comments: 10414
592. Ameister12
8:31 PM GMT on June 05, 2013
Slight risk for Western/Central Florida. Likely for isolated tornadoes and damaging winds.
Member Since: August 9, 2009 Posts: 10 Comments: 5026
591. Ricki13th
8:31 PM GMT on June 05, 2013
Quoting SouthernIllinois:

You see the center shifting or relocating under the deeper convection...?


Its done that already. It now trying to wrap itself up.
Member Since: May 28, 2013 Posts: 0 Comments: 405
590. DataNerd
8:31 PM GMT on June 05, 2013
20:16:00Z 26.000N 87.050W 987.9 mb
(~ 29.17 inHg) 177 meters
(~ 581 feet) 1008.1 mb
(~ 29.77 inHg) - From 78° at 33 knots
(From the ENE at ~ 37.9 mph) 23.0°C
(~ 73.4°F) 21.2°C
(~ 70.2°F) 33 knots
(~ 37.9 mph) 32 knots
(~ 36.8 mph) 1 mm/hr
(~ 0.04 in/hr) 32.0 knots (~ 36.8 mph)
97.0%
20:16:30Z 26.000N 87.100W 987.9 mb
(~ 29.17 inHg) 177 meters
(~ 581 feet) 1008.2 mb
(~ 29.77 inHg) - From 77° at 32 knots
(From the ENE at ~ 36.8 mph) 23.1°C
(~ 73.6°F) 21.4°C
(~ 70.5°F) 35 knots
(~ 40.2 mph) 32 knots*
(~ 36.8 mph*) 0 mm/hr*
(~ 0 in/hr*) 29.3 knots* (~ 33.6 mph*)
91.4%*


pressure falling prior to southern turn: 20:25:00Z 25.867N 87.400W 927.8 mb
(~ 27.40 inHg) 698 meters
(~ 2,290 feet) 1005.3 mb
(~ 29.69 inHg) - From 80° at 30 knots
(From the E at ~ 34.5 mph) 20.6°C
(~ 69.1°F) 18.0°C
(~ 64.4°F) 30 knots
(~ 34.5 mph) - - - -
Member Since: June 24, 2012 Posts: 0 Comments: 1546
589. nigel20
8:31 PM GMT on June 05, 2013
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.

Western Cuba has been getting quite a bit of rain as well.
Member Since: November 6, 2010 Posts: 11 Comments: 8139
588. flcanes
8:30 PM GMT on June 05, 2013
Quoting Autistic2:
How fast do H.H. fly?

IDK
Member Since: August 20, 2012 Posts: 13 Comments: 1254
587. flcanes
8:30 PM GMT on June 05, 2013
Landfall between cedar key and panama city, between 2 pm tomorrow and 2 pm friday.
Member Since: August 20, 2012 Posts: 13 Comments: 1254
586. DataNerd
8:30 PM GMT on June 05, 2013
Quoting SouthernIllinois:

You see the center shifting or relocating under the deeper convection...?



Thats already been confirmed by recon scroll down.
Member Since: June 24, 2012 Posts: 0 Comments: 1546
584. Ricki13th
8:30 PM GMT on June 05, 2013
Quoting SouthernIllinois:
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.



One heck of a moisture field protecting the COC. Allowing very little to penetrate. Doesn't always need great conditions to get a storm to form.
Member Since: May 28, 2013 Posts: 0 Comments: 405
583. will40
8:30 PM GMT on June 05, 2013
you will see the center relocate many times with a developing storm
Member Since: September 19, 2005 Posts: 2 Comments: 4251
582. Doppler22
8:30 PM GMT on June 05, 2013
I have a short blog on my own Hurricane Alert System... Not much but its just for the fun of it... Look if you'd like

Link

http://www.wunderground.com/blog/Doppler22/commen t.html?entrynum=5
Member Since: February 13, 2012 Posts: 11 Comments: 3769
581. Autistic2
8:30 PM GMT on June 05, 2013
How fast do H.H. fly?
Member Since: August 29, 2008 Posts: 0 Comments: 470

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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.