Thursday, March 25, 2021 5:30 P.M.
Lots of wind, possibly strong storms
The atmosphere is certainly in a severe storms state. Moisture rushing northward and really strong wind fields to work with. That’s pretty much the story from the deep south to the Great Lakes region. But, I’ll try to pin things down to more detail.
The easiest part of the forecast is the location of the worst weather. Severe thunderstorms and tornadoes are likely over a large part of the south – eastern MS, northern half of AL and most of TN are the primary spot for damaging storms.
Next, northeast MO, southeast IA and northern IL and IN are likely to see heavy rain and, especially, very strong winds. These will not be thunderstorm wind gusts. The combination of storm development and upper level winds will combine to generate sustained winds over 40 mph with gusts over 60 mph for several hours tonight. I wouldn’t be surprised if a few reports of gusts over 70 mph are measured.
So, I guess the good news is that the worst weather conditions expected tonight will be either considerably north or south of the Ohio River. But, what happens to that space in between? That’s us.
The Storm Prediction Center has the western half of Kentucky and southwest corner of IN (and others) in a Tornado Watch until Midnight. They expect a line of strong to severe thunderstorms to develop just east of the Mississippi River during the next hour or so. They expect intensification of the line as it sweeps eastward toward us. Primary threat time for the Louisville area will be 9 P.M. until 11 P.M. They say severe storms are likely and some tornadoes are expected, especially over the western third of KY and TN.
Most forecast models are downplaying this line of storms for central KY and southern IN. We’ll have to keep an eye out to see how things evolve over the next few hours. The models suggest the instability will remain quite low tonight. If that is correct, we’ll see a quick-hitting line of gusty thunderstorms tonight, but no major problems.
However, a different problem could create troubles for a few hours after Midnight – strong winds! Several paragraphs above I mentioned the non-thunderstorm winds likely northwest of us this evening. Well, as the surface storm center moves across Indiana this evening, the door opens for the northwesterly winds behind the system to rotate southeast into our area. We’ll see about 4-6 hours of wind gusts above 40 mph here and probably over 50 mph over southern IN.
Note to storm watchers
We expect to see a relatively narrow line of rain/thunderstorms to cross the area during the evening. Severe storms will likely be embedded in this line, especially to our west. If, however, if you see any “discrete” cells of thunderstorms, WATCH OUT. These stand-alone single cells can be very dangerous in situations like this. The strongest tornadoes almost always are produced by these rapidly moving discrete cells. It is not too uncommon for very intense dynamics (the strong wind fields) to overcome a weak moisture supply. The next six hours could become very interesting.
A PREDICTION: A Severe Thunderstorm Warning will be issued for Jefferson County KY later this evening. (When is the last time you remember when a storm Warning has NOT been issued for Jefferson County as a line of strong thunderstorms passes through? Yep, I can’t remember either. )