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Odds for severe weather Thursday increase slightly

A ‘slight’ to ‘marginal’ threat of damaging winds, isolated tornadoes exists from the early morning hours through the day
Published: Oct. 26, 2021 at 5:14 PM EDT|Updated: Oct. 27, 2021 at 4:13 PM EDT
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TALLAHASSEE, Fla. (WCTV) - A threat for severe weather remains for early Thursday morning through the rest of the day, as a potent storm system is forecasted to move into the Southeast.

The Storm Prediction Center’s Wednesday afternoon update extends the level 2 (slight) risk eastward into Liberty and Franklin counties as well as portions of Leon and Gadsden counties through 8 a.m. Thursday morning. The lower level-1 risk for the early morning hours was pushed east to just west of I-75.

The risk for Thursday increased to a level 2 risk for most of the viewing area after 8 a.m. The higher risk includes the Big Bend and Georgia locations near the state line.

SPC's Severe Weather Outlook for Wednesday, Oct. 27 valid through 8 a.m. ET Thursday.
SPC's Severe Weather Outlook for Wednesday, Oct. 27 valid through 8 a.m. ET Thursday.(SPC/NOAA/WCTV Pinpoint Weather)
SPC Severe Weather Outlook for Thursday, Oct. 27, 2021 issued at 1:28 p.m. ET. The forecast is...
SPC Severe Weather Outlook for Thursday, Oct. 27, 2021 issued at 1:28 p.m. ET. The forecast is valid for after 8 a.m. ET Thursday.(SPC/NOAA/WCTV Pinpoint Weather)

The primary severe weather modes of concern, though low, are damaging thunderstorm winds and isolated tornadoes.

Wind shear, the different wind speeds and directions with increased height above the Earth’s surface will be fairly high as the cold front and squall line approach the viewing area early Thursday morning through the rest of the day. But a limiting factor will likely be the limited instability through the night into the morning. One exception may be, as the SPC noted Wednesday afternoon, higher moisture levels and convective energy as a warm front lifts north would increase the odds of severe weather in the southwestern viewing area. Recent guidance model runs do show higher dewpoints and convective energy (CAPE) over Franklin County with one model extending that slightly farther north in the Big Bend.

As daytime heating increases during the morning and early afternoon, the line may get a boost in improved convective energy. This would allow for better odds of stronger to severe thunderstorms.

Updated severe weather threat for the Big Bend and South Georgia and risk of severe modes for...
Updated severe weather threat for the Big Bend and South Georgia and risk of severe modes for Thursday, Oct. 28. Updated at 2 p.m. Oct. 27.(WCTV Pinpoint Weather)

The timing hasn’t changed much since Tuesday’s update, but the small-scale, high-resolution models differ on the idea of a second line of showers and storms developing along the cold front. But confidence remained high of the first round of showers and embedded thunderstorms moving into the western viewing area after midnight and advancing eastward through the rest of the morning. The rain could impact those on the drive to work.

Stay tuned for the latest on the severe weather threat for Thursday. Be sure to download the WCTV Pinpoint Weather App to receive location-based weather alerts on your device, radar scans, and updates from the weather team.

This story was updated at 4 p.m. to include a video update on new advisories as well as possible timing of the rough weather.

TALLAHASSEE, Fla. (WCTV) - A potent storm system forecast to move through the Southeast Wednesday into the Halloween weekend will bring a low-end threat of damaging winds and isolated tornadoes to the viewing area from early Thursday into the rest of the day.

The Storm Prediction Center has placed a level 1 out of 5 (marginal) risk of severe weather from late Wednesday night through 8 a.m. Thursday for Liberty and Franklin counties. For Thursday (after 8 a.m.), the SPC includes nearly the entire viewing area for the level-1 threat with southeastern portions of Suwannee and Lafayette counties under a higher level 2 risk (slight). The modes of concern will be damaging winds and a few tornadoes.

The Storm Prediction Center's Severe Weather Outlook for Wednesday, Oct. 27 (8 a.m. to 8 a.m....
The Storm Prediction Center's Severe Weather Outlook for Wednesday, Oct. 27 (8 a.m. to 8 a.m. Oct 28).(SPC/NOAA/WCTV Pinpoint Weather)
The Storm Prediction Center's Severe Weather Outlook for Thursday, Oct. 28, 2021.
The Storm Prediction Center's Severe Weather Outlook for Thursday, Oct. 28, 2021.(SPC/NOAA/WCTV Pinpoint Weather)

A large trough of low pressure in the mid- to upper-levels of the atmosphere was advancing westward Tuesday afternoon. That trough is forecast to help the development of a center of low pressure at the surface along with a cold front. By Wednesday morning, the low is forecast to inch eastward through Oklahoma with the front dragging through eastern Texas.

The weather for the Big Bend and South Georgia is forecast to be tranquil for the daytime hours Wednesday, but things will begin to change after dusk. Models are agreeing on switching the wind flow from the north to the southeast. This will increase the low-level moisture amounts through the night, but how quickly the wind shift and dewpoints climb will be crucial for determining how much rain and how buoyant the atmosphere will be. The moisture, as well as the forcing from the front and trough, will be mechanisms of the development of showers and thunderstorms.

So far, the timing of arrival of the rain and storms will be after midnight and through the rest of Thursday. The smaller-scale, short term models are hinting at the possibility of two waves of showers and thunderstorms. The first would be a wider (west-to-east) swath of rain and embedded thunderstorms that arrives to the western viewing area well ahead of the front after midnight and moving east through the early morning hours. A second, narrower line of showers and thunderstorms could develop along the cold front as it moves into the Apalachicola and Chattahoochee river basins around 8 a.m. Thursday and move eastward. The second line, based on guidance models, would have a better environment for severe weather with respect to wind shear. As the second line moves farther east, it could enter a more thermodynamically-favorable environment as daytime heating increases. The setup would increase the threat of stronger to severe thunderstorms - especially for eastern locations as well as Northeast Florida and into Central Florida.

Severe Weather Threat for Thursday, Oct. 28 for the Big Bend & South Georgia.
Severe Weather Threat for Thursday, Oct. 28 for the Big Bend & South Georgia.(WCTV Pinpoint Weather)

Stay tuned for the latest on the severe weather threat for Thursday. Be sure to download the WCTV Pinpoint Weather App to receive location-based weather alerts on your device as well as updates from the weather team.

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