Hazardous Weather Update for Wakulla County

We will continue to monitor this event and have response crews for Fire, Law Enforcement and Public Works ready to respond as needed.

-  The potential exists for Severe weather

-  Potential for straight line winds in excess of 70 mph

-  Potential for isolated tornadoes

Storm tides are predicted for Wakulla County of 5-7 feet.  This is similar to the levels experienced last year as Hurricane Gustav made landfall in Louisiana and about 1-foot higher than experienced a few weeks ago in Tropical Storm Ida.  We should expect to see minor flooding of coastal roadways in St. Marks, Panacea and Mashes Sands.  Also, for Gustav, we experienced minor road flooding in Shell Point with some homes on the lower end of Mashes Sands experiencing minor flooding.  Coastal residents in areas prone to coastal flooding should monitor this system and take steps to protect property.

Anticipated rainfall amounts of 2-4 inches with isolated higher amounts possible.

Scott L. Nelson, FPEM
Wakulla County Emergency Management Director
Wakulla County Sheriff's Office
850.926.0861

In this update:

Severe weather threat increasing starting late tonight and into Wednesday

Flash Flood Watches issued

Coastal Flood Warnings and High Surf Warnings issued

An area of low pressure has developed this morning just off the Southern Texas Gulf Coast.  It is this area of low pressure that will track northeastward over the next 24 to 36 hours and combine with a strong upper level system to produce widespread hazardous weather across our region.

As this area of low pressure moves northeast, a frontal boundary now located south of the region will begin to lift back northward. As this frontal boundary moves back to the north, a more moist and unstable airmass will overspread the region making the atmosphere more favorable for severe weather and heavy rains. As the upper level disturbance approaches, strong wind shear aloft will combine with this unstable airmass to produce a period of severe weather across the entire region. While there is still some uncertainty with how unstable  the airmass will be on Wednesday, confidence is increasing that enough instability will be present to produce a significant severe weather event.

Severe Weather Threat:

The latest update from the Storm Prediction Center places our region within a slight risk for severe weather. However, notice that the image at the right shows increased probabilities for
severe weather. These numbers have increased from 15% probability of severe weather to 30% probability for severe weather across a large portion of the region.  Also, notice the area within the blue hatching. Areas within this blue area are at an increased risk for significant severe weather, like destructive winds in excess of 70 mph and strong tornadoes.  It is possible if better agreement in our computer models develops and greater instability is indicated, a portion of our region will be upgraded to a moderate risk area later today.  For more information on these outlooks, please visit http://www.spc.noaa.gov/.

At this time, we expect there to be an isolated tornado threat developing across the Florida Panhandle late tonight and early Wednesday morning.  This threat may spread into Southeast
Alabama just before daybreak.  Then after daybreak, the threat for isolated tornadoes will shift into Southwest Georgia and the Florida Big Bend.  By mid morning on Wednesday, a squall line will move into Southeast Alabama and the Florida Panhandle and race eastward.  This squall line will be capable of producing destructive winds in excess of 70 mph and isolated tornadoes.

Coastal Flooding:

A coastal flood warning is now in effect from 6 pm ET this evening through 6 am ET Thursday morning from Destin to the Suwannee River.

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

The latest computer model runs show storm surge values of 2 to 4 feet from Apalachicola eastward to Destin.  Storm surge heights up to 2 feet are possible west of Apalachicola. In addition to the potential for coastal flooding, high surf will begin to impact the beaches of the Florida Panhandle from Destin to Saint George Island late tonight and into the day on Wednesday.  This will cause moderate to major beach erosion as surf heights build to as high as 10 feet along the Walton and Bay County beaches.  High surf is not expected to impact coastal areas of Wakulla County eastward to Dixie County.

Coastal Flood Summary:

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

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 likely with isolated higher amounts up to 8
inches possible.  Somewhat lesser totals of 2 to 4 inches are expected across the eastern half of the region.  Please see the map below for more details:

Notice that the heaviest totals are located from Albany to Apalachicola and areas to the west.  If the low pressure area tracks further to the east, this heavy rain could impact areas  further to the east than presently expected.

Timing:

Overall the timing of this event has changed very little from Monday’s webinar, thus those images have been used here.  If anything, the models are indicating a slightly faster progression with the arrival of severe weather around 3 hours earlier than indicated in Monday’s webinar.  If any changes to the timing of this system are needed, these new graphics will be provided on this webinar at 230 pm ET this Tuesday afternoon.

Watches/Warnings/Advisories Currently in Effect:

**Coastal Flood Warning in effect for Walton, Bay, Gulf, Franklin, Wakulla, Jefferson, Taylor, and Dixie Counties

**High Surf Warning in effect for Walton, Bay, and Gulf Counties

**High Surf Advisory in effect for Franklin County

**Flood Watch in effect for the Eastern Florida Panhandle, Southeast Alabama, Southwestern Georgia, and the Western Florida Big Bend

**Gale Warning in effect for the coastal waters beginning early Wednesday morning

Summary:

**Severe Weather is becoming more likely with this system.

**The main threat initially will be for isolated tornadoes overnight and into the early morning hours.  Then destructive winds and isolated tornadoes will be possible with the squall line
Wednesday mid morning and afternoon.

**Coastal Flooding is expected along the entire coastline with highest totals from Ochlockonee Bay eastward to the Suwannee River

**High Surf will impact the beaches of Walton County eastward to Franklin County starting tonight.

**Inland flooding is possible with locally heavy rainfall beginning early Wednesday morning and continuing through the day.

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.

This information originally published on December 1, 2009.

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Written by :

mkwestmark

 

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