Huntsville topped out at 93ºF for the third time in 2017 on Tuesday; Muscle Shoals hit 95ºF. Both of those are the highest temperatures for the year so far! Expect a low in the lower-70s with a fair sky and a light wind overnight; hot, humid weather on Wednesday along with a weak upper-air disturbance sets the stage for some widely scattered, locally-heavy thunderstorms.
Spotty storms Wednesday develop as early as 11 AM and last through sunset. It won’t be an all-day, excessively-heavy, downpour-after-downpour situation like last week, but some of the storms have potential to drop a quick 0.50″ to 1.00″ of rain because they move so slowly. The same goes for scattered storms on Thursday, Friday and Saturday: locally-heavy rain plus slow movement can bring a lot of rain to very few places, a little rain to most of the area, and zero rain to a few spots as well.
Any measurable risk of severe storms stays well north of Alabama and Tennessee; however, a summertime storm can turn nasty in a heartbeat! The processes creating the storms aren’t enough to sustain them for long distances, so they will occasionally collapse in a torrent of heavy rain and strong winds as rain-cooled air falls to the ground.
How much rain through Saturday? It’s been a wet summer so far to say the least, but Huntsville shows a small surplus for the entire year to date: 0.92″ above average. We need close to an inch of rain per week to stay near or slightly above the norms for this time of year, and these scattered downpours in the forecast should be able to take care of that for the majority of North Alabama and Southern Tennessee.
The greater threat of rain and storms in the picture for Friday and Saturday comes from two different sources: another weak upper-air disturbance on Friday, a weak ‘cool front’ on Saturday. That front won’t make much difference in the temperature around here, but it will knock down the humidity and help cut down (not eliminate) the widespread showers and storms from Sunday through the first part of next week.