7:43PM July 19, 2018

FRIDAY P.M. SEVERE WEATHER POSSIBLE… Strong to severe thunderstorms are possible across the northern half of Alabama late on Friday into Saturday morning. The storms happening across south Alabama and northwest Florida this (Thursday) evening are producing heavy rain and lightning, but are not severe. It’s important to note that the Storm Prediction Center maintains vast majority of south Alabama and northwest Florida in their “general thunderstorm” zone, meaning severe weather is NOT expected across much of our local area. This will likely be a damaging wind/derecho-type event for north and central Alabama, if the threat materializes. Just because the tornado risk will be quite low, as we were reminded in June, damaging straight line winds in derecho-type events can be extremely damaging. Let’s talk details…

LEVEL 1 RISK FOR SOUTH/CENTRAL ALABAMA… The lower-end, marginal (Level 1) risk of strong to severe storms includes northern fringes of Clarke, Monroe, and Butler counties in our local area. The remainder of south Alabama and northwest Florida is included in the “general thunderstorm” zone, meaning strong storms will be possible (per our daily usual as of late) but not nearly as likely to occur compared to areas to our north. Widespread severe weather is NOT anticipated when an area is included in the general thunderstorm zone. I’ll be closely monitoring the decaying line of storms on Saturday morning as it approaches our area from the north, but most likely, our local area will not have any major issues. Significant severe weather is possible to our north, however…

SEVERE STORMS TO THE NORTH… Much of the Tennessee River Valley and northwest Alabama will have the highest potential of experiencing severe thunderstorms late Friday into Saturday. Places like Huntsville, Marion, Moulton, Russellville, Decatur, Muscle Shoals, Florence, and Athens are included in the Level 3 “enhanced” risk area valid Friday evening into Saturday. This is where widespread severe weather is more likely The Level 2 “slight” risk includes Birmingham, Tuscaloosa, Hoover, Gadsden, Anniston, Fort Payne, Oneonta, Cullman, Jasper, and Fayette. The most likely scenario is that a band of intense thunderstorms will move into northwest Alabama Friday evening. The main risk will be due to damaging straight line winds and large hail. The tornado risk is low, but it’s not zero.

HYPE MACHINE ALERT… I’ve had several questions today about a specific post making the rounds on social media. As I’ve stated many times before, I do not consider it wise (at all) to post one model/one parameter solutions. CAPE/instability values are one component of thunderstorm formation. CAPE, or Convective Available Potential Energy, values will be high across the Deep South (including our area) on Friday and on Saturday. Here’s the important part that the viral post fails to mention… CAPE is high EVERYDAY in the summer months around here. It’s not unusual to see CAPE values in excess of 2,000-2,500 j/kg. That’s just the nature of living in the Deep South. We have thunderstorms, almost DAILY in summer. Please remember before sharing “clickbait-y” one parameter, one model solutions that we need the full picture to make an informed forecast decision, not just one model.

Let me know if you have specific questions. Have a wonderful evening!

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