Risk of severe weather in the Southeast Thursday into early Friday

Here we go again. Another spring day, another threat of severe weather in the South.

The Storm Prediction Center in Norman, Okla. has placed the Big Bend and South Georgia under a level 3 risk of severe weather Thursday into early Friday morning (before 8 a.m. ET).

Severe weather risk for Thursday into early Friday morning. Source: Storm Prediction Center / NOAA.

But this approaching storm system isn’t as clear cut when it comes to thunderstorm development timing, location, and design. Let’s explain as best I can.

MId-level wind and pressure pattern as of Wednesday morning. Source: University of Wyoming.

A trough of low pressure, shown above over the Texas and Oklahoma panhandles, was moving eastward Wednesday morning. This trough is helping to develop a center of low pressure at the surface. Of course, cold and warm fronts will move along with it. The warm front is expected to move northward through the Big Bend and South Georgia Thursday morning as the low inches eastward, removing the nice dry weather the area has been experiencing since early week and inserting that muggy, juicy and buoyant air into the area.

Along with moist (eww) air, the stronger low along with the trough of low pressure aloft will once again provide some fairly decent wind shear – especially in the lower levels. All you need is a lifting mechanism (the trough and/or cold front) and you got yourself another threat of severe storms – specifically damaging winds and tornadoes. There is a chance of hail, but so far I believe it’s a lower risk.

Now here comes the hard part. Some runs of the global models are throwing in two “waves” of energy ahead of the trough. Those waves are more or less ways of providing lift. But the newest runs of the American GFS and European models are hinting at two waves of showers and storms – one in the afternoon for the Big Bend and South Georgia, while the second one comes after midnight. The GFS is not as aggressive with intensity as the European. Smaller-scale, convection-allowing models are also differing with rain/storm intensity of waves one and two. In other words, there is not a lot of agreement with what and when – but there is confidence of a setup that will allow for some thunderstorms to become severe. And some of these storms may not necessarily be from a squall line – they could be isolated, and pose a risk of becoming supercells.

The Wednesday morning model run of the NAM-3km showing its scenario with strongest round of convection for the Big Bend and the South Georgia border counties Friday morning. Source: College of DuPage.

If you live in the Southeast, be sure to check on the latest forecast for your area. Have multiple ways to receive weather watches and warnings (e.g. NOAA Weather Radio, smartphone app, etc.).

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