Thursday, June 29, 2023

Mesoscale Convective System to the North


The weather sure has been throwing some curves this summer, reminds me of 2012 or 2009. A mesoscale convective system is moving out of mainly Illinois, but also some storms have formed ahead of the main cluster in Kentucky and Tennessee, prompting a Severe Thunderstorm Watch for basically all of Middle Tennessee, including the counties that border Alabama. 


And you can see, there have been numerous reports of damaging winds up in the Ohio River Valley back up into the Midwest already today. 

We've already got a temperate of 95 in Muscle Shoals, 91 in Jasper, with dewpoints in the lower 70's. So the excessive heat is real, but for anybody who does get any of these storms that survive, those storms could pack a punch in the heat and humidity. 

And the Storm Prediction Center has extended a severe thunderstorm outlook, Level 2 out of 5, for the Tennessee Valley the rest of today into tonight. The main threat is damaging thunderstorm winds, although there is a low risk of some large hail in some storms as well. This is not all that unusual for summer, but it's a little beyond what was expected around here today. If we do see some rain and storms, obviously that may mitigate the excessive heat problem for some folks. Don't count on that either way though. This summer has had some really unusual patterns, even though it's far from unheard of to have MCS trying to move in or graze the area even when the heat and humidity do get extreme. 

So I noticed this going on and decided to post about it. 

2:11 PM - Okay, now the new Severe Thunderstorm Watch extends down to counties like Marshall, Dekalb, Morgan, Lawrence, and Franklin in Alabama. Of course it also includes Huntsville and Muscle Shoals in far Northern Alabama. It does not include Cullman, Winston, Walker, Marion, Blount, or Etowah Counties as of right now. But remember that a watch means severe thunderstorms are possible in and close to the watch area. And there are storms in Middle Tennessee showing signs of severe winds. 

2:46 - From the Weather Prediction Center about the heat. 

3:10 PM - The storms appear to be in a weakening phase. Some folks are getting some rain on a hot day though. 

3:17 - Now a Severe Thunderstorm Warning for places like Lawrenceburg and Pulaski in Lawrence and Giles Counties in Southern Middle Tennessee. Storm may be producing wind gusts of 60 miles per hour and quarter sized hail. 

4:24 PM - The storms are moving into Northwest Alabama now and have a history of producing golfball sized hail in Tennessee. Also be aware they can produce damaging wind gusts. I saw a report of a large tree down, think it was from Lawrence County, TN, might have been blocking a roadway. So take these warnings seriously enough to at least stay inside, away from windows. 

One thing about it, the places getting large hail can kiss the excessive heat goodbye for a little while. Of course it cranks back up tomorrow, but the break from it is nice. 

4:36 - The hail signatures are not looking as bad, probably closer to quarter size now, but that's still severe criteria, and so are wind gusts up to 60 mph. 

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