This has been the summer of the same-old, same-old! We have had very few totally ‘dry’ days in North Alabama; however, some communities have had practically nothing rain-wise in the past two weeks.
Others with more than two inches of rain are wondering when it will stop, and that’s the rub this time of year: unevenly-spread, widely-scattered, hit-or-miss storms.
But why is it so uneven?
It’s all about the beast we’re dealing with here: the ‘scattered’ or ‘spotty’ typical summertime thunderstorm. You can see how they ‘bubble up,’ barely move, and then collapse.
What’s happening here is that the storm is using up as much available moisture as possible: pulling it in from all sides like a vacuum pump in a pool. The suction line on a vacuum may only be a few inches wide, but it will drain a pool if you give it enough time.
A thunderstorm is similar to that: like a small vacuum pulling in a LOT of the moisture nearby. They’re efficient at taking the thick, tropical humidity and converting it to rain! They just do it a lot faster than a pool pump, and they can drop billions of gallons of water over relatively small areas.
So, to really grasp the ‘rain chance,’ you have to think bigger than the spot you’re watching right now. We’re looking at a region for a chance of rain because there’s no way to be that specific with these chaotic little air bubbles that end up creating big, monstrous thunderstorms in this summertime heat.
So is this the start of a drought?
Alabama and Tennessee endured a brief season of drought late last summer into the Fall of 2019, but we do not expect that same exact scenario this go-around.
The latest guidance from the Climate Prediction Center shows a better-than-average chance of daily scattered thunderstorms through August 20th. While those storms are unevenly spread, spotty, and hit-or-miss, they are also very heavy: the heaviest of them producing more than 1-2″ in less than 60 minutes.
There could also be some tropical influence later in the month.
The Atlantic is all quiet right now (August 6th), but there are signs of tropical development around the Caribbean and Gulf of Mexico within the next two weeks.
NOAA’s Weather Prediction Center released the August update to the 2020 hurricane season forecast on Thursday, and it’s calling for an ‘extremely active’ season: