[tabi] FW: Significant Storm System To Affect North Florida By Tuesday Night - 11/30/2009

From: Lighthouse of the Big Bend <lighthousebigbend@xxxxxxxxx>
To: tabi <tabi@xxxxxxxxxxxxx>
Date: Mon, 30 Nov 2009 09:19:48 -0500
From: Chris Floyd [mailto:floydchris@xxxxxxx]
Sent: Monday, November 30, 2009 7:25 AM

A Severe Weather Briefing for North Florida from the Tallahassee
Forecast Office of the National Weather Service can be found at the
following web site:

http://www.bbcoad.org/index.html#weather

Early Morning Weather Briefing for Emergency Managers November 30, 2009
• Significant Storm System to affect the region by Tuesday night
• Multifaceted hazardous weather threat expected including severe weather

An area of low pressure will develop
over the Western Gulf of Mexico on Tuesday
afternoon. This area of low pressure will initially move
along a stalled frontal boundary across the
Northern Gulf. As this low moves to the
northeast, the front will begin to lift back north
bringing a more moist and unstable airmass back into the region.

In addition to the incoming moist and unstable airmass, this low
pressure area is forecast to strengthen rapidly as it interacts with a
strong upper level system moving across the Lower Mississippi River
Valley. This will result in strong southerly winds ahead of the low
pressure system by Wednesday morning. These strong onshore winds will
create very high surf and the potential for coastal flooding,
particularly in the flood prone areas of Apalachee Bay. Finally, this
storm system will also bring the potential for very heavy rainfall.
Thus, urbanized flooding during the event and river flooding in the
days to follow is certainly possible with this system.


Severe Weather Threat:
On Wednesday, the Storm Prediction Center has placed our region in a
Slight Risk for severe weather. Though, there is certainly potential
for some of this risk area, especially near the coast, to be increased
to a moderate risk in the days to come. This is because there is a
considerable
amount of wind shear associated with this system. However, as is
usually the case, the amount of instability is uncertain. As Wednesday
approaches we will likely have a better understanding of how unstable
we will get across the region. If, more instability is realized, the
potential exists for a significant severe weather event to accompany
this system with destructive straight line winds and isolated
tornadoes, especially with a squall line along the cold front on
Monday afternoon.

Coastal Flooding:
Currently, areas from Cape San Blas to the Suwannee River Entrance are
under a coastal flood watch. This means that we are seeing indications
that inundation of low lying areas along the coastline is possible. If
confidence in coastal flooding continues to increase, this watch may
be upgraded to a warning later tonight or on Tuesday.

Strong southerly winds ahead of this system on Wednesday morning will
begin to push water into Apalachee Bay. These strong onshore winds
will likely coincide with the time of high tide on Wednesday
afternoon. As you can see from the tide chart below, there is very
little difference between the high and low tides on Wednesday
afternoon, thus the potential exists for a prolonged period of
inundation for low lying areas along the coast.

It should be noted that some of our storm surge models are showing
storm surge values in excess of 4 feet in Wakulla, Jefferson, Taylor,
and Dixie Counties, which would create overall storm tides near 7 to 8
feet, or values very similar to Hurricane Gustav in 2008.

For more information on Storm Tide visit :
http://www.nws.noaa.gov/mdl/etsurge/index.htm?coast=gulf&load=gfmap.htm&map=0-48

In addition to the coastal flood impacts, dangerous high surf which
could cause beach erosion from Saint George Island westward to Destin
is possible. The surf could reach heights of 7 to 10 feet,
particularly from Panama City to Cape San Blas.

Inland Flooding:
The rainfall with this system is predicted to be heaviest across the
western half of the region where storm total amounts of up to 4 to 6
inches is possible. Somewhat lesser totals of 2 to 4 inches are
expected across the eastern half of the region.

Timing:
At present, we are expecting the threat for severe weather and heavy
rain to develop late Tuesday evening across the Florida Panhandle and
then begin to spread further inland into Southeast Alabama on
Wednesday morning. Then, by mid morning Wednesday, a squall line is
predicted to develop and spread eastward rapidly across the region.
This squall line could be particularly severe if enough instability is
in place. The main threats early in the event will be for isolated
tornadoes. Then, with the squall line, destructive straight line winds
and isolated tornadoes will be possible.
Look for timing graphics this afternoon in our webinar at 230 pm EST.

Watches Currently in effect:
**Coastal Flood Watch in effect for Gulf, Franklin, Wakulla,
Jefferson, Taylor and Dixie from Wednesday morning through Thursday
morning

**Gale Watch in effect for the coastal waters from late Tuesday night
through Thursday morning.

Summary:
**A significant storm system with the potential for severe weather,
coastal flooding, inland flooding, and beach erosion will approach the
region Tuesday night and into Wednesday.

**Coastal flooding, beach erosion and heavy rainfall are more certain impacts.

**Severe weather is certainly possible but there remains some
uncertainty to how significant the impact will be.

A reminder to our emergency managers, please check your email for the
invitation to the webinar briefing on Monday morning.

The National Weather Service in Tallahassee will continue to monitor
this storm’s progress over the next couple of days. If you have any
questions, please give our office a call at 850-942-8833 or on our
toll free line at 800-598-4562 and ask to speak to a meteorologist. We
are available 24 hours a day, 7 days a week. You can also reach us on
our Southern Linc phone at 1*77*184.

Chris Floyd
Manager
Big Bend Community Organizations Active in Disaster
A Program of VolunteerLEON

850/241-3565 (Cell)




-- 
Lighthouse of the Big Bend
Guiding People Through Vision Loss
1286 Cedar Center Drive
Tallahassee, FL 32301
(850) 942-3658
Check out the TABI resource web page at http://acorange.home.comcast.net/TABI
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[tabi] FW: Significant Storm System To Affect North Florida By Tuesday Night - 11/30/2009

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