Questions Around Tonight’s Storms

If you were out early this morning, you know it was a cool start to the day; that’s not generally how you would think it should feel when we’re talking about the potential for severe weather within the next 18 hours! The Storm Prediction Center has placed parts of Alabama and Tennessee in a SLIGHT RISK for tonight and early Thursday morning: SPC Outlook.

Morning Lows as of 7 AM:
39º – Valley Head
42º – Crossville
43º – Cullman, Russellville
45º – Fort Payne, Muscle Shoals (TVA)
48º – Decatur
50º – Huntsville International, Muscle Shoals (NW Alabama Regional Airport)

Here’s the 10 AM analysis of temperature and dewpoint around the South; the dewpoint is very important when it comes to instability that fuels powerful storms. There are some documented cases of tornadoes in Alabama with dewpoints in the mid-50s, but we generally see severe storms associated with air masses that have dewpoints in the 60s and 70s. Higher dewpoints bring much more energy for storms, so as we watch the southerly wind drag this warm, humid air north, our threat will hinge on just how far north the really juicy air (dewpoints of 64º plus) can get!

And here’s the forecast meteogram for Huntsville’s temperature and dew point. The yellow arrow points to the highest forecast dewpoint being just above 60º around 3 to 4 AM:

Here’s how the timeline will go tonight:

5 to 7 PM: Strong to severe storms erupt from Arkansas to Louisiana along a cold front that is moving southeast. Those storms will likely form a squall line that moves into Mississippi.

8 PM to 10 PM: A line of intense thunderstorms will be near the Mississippi River from West Tennessee through the Mississippi Delta west of I-55. This is the area where the best combination of instability and dynamics could lead to some very powerful storms as well as tornadoes.

10 PM to 1 AM: Line of strong storms moves through North Mississippi toward Northwest Alabama and Southern Middle Tennessee. Intensity of individual storms will slowly fade; however, some of the storms will still be quite strong as they approach Marion, Lamar, Franklin, Colbert, and Lauderdale Counties in Northwest Alabama as well as Hardin and Wayne Counties of Southern Tennessee.

1 AM to 3 AM: Storms steadily weaken but could still be heavy with a small potential for strong winds and some rotating storms through North Central Alabama. The severe weather threat is low; however, that does not mean it is ZERO.

3 AM to 5 AM: The line of storms will be much less intense over Northeast Alabama; the severe threat is very, very marginal for Marshall, DeKalb, Jackson, Etowah, Cherokee, Lincoln (TN) and Franklin (TN). Rainfall rates will come down significantly, and a few places may barely get enough rain to measure.

The Bottom Line

You need to have a way to get weather information tonight just in case a warning is issued for your area. We are not convinced that this will be a significant severe weather event on a big scale, but as you know, it just takes ONE storm to be significant for somebody. We will be watching it closely all night so that you don’t have to; just have a way to get a warning:

NOAA Weather Radio is your best bet as long as you have it in alert mode. We also offer several mobile applications:

- Live Alert 19 is free, but it is not a warning application. We use that to communicate when we are on the air.

- iMap Weather Radio and MyWarn are apps you have to pay for, but they do allow you to get location-specific warnings that no one else can provide.

- If a tornado warning is issued for any county in the WHNT viewing area, we will be there to cover it for you.

-Jason
Connect with me!
Google+: Jason Simpson
Facebook: Jason Simpson’s Fan Page
Twitter: @simpsonwhnt