Humidity Up, Afternoon Rain, Thunderstorm Possible.

I’m writing via Chromebook in an Atlanta hotel. Not optimal. I’ll be light on graphics this morning.

Today’s dewpoint will climb close to 70. That’s near-oppressive humidity.

Today’s high is 93. Add that to a more humid airmass and you get a heat index up to 97 this afternoon.

The heat and humidity combo should break the cap and cause rain and thunderstorms to form in Middle Tennessee beginning mid-afternoon. Exactly when and where rain and storms will develop is unknown, but models are consistent popping them up in our region.

HRRR model thru 4 PM Sunday

Lightning and locally heavy downpours will be the main features of developing storms, which should begin to die off after sunset.

This Week

Another storm lottery again Monday: hot, humid, chance of that afternoon shower or thunderstorm.

Stronger storms are possible late Tuesday as a front tries to dive southward from Kentucky into Middle Tennessee. Models think the worst of it will stay north of us, though. There is significant uncertainty over how far south these will go and whether they’ll even reach us on Tuesday. Even if storms make it, there’s a question about whether they’ll be well organized and strong or circus music will be playing and the storms will be weak.

If the front doesn’t deliver storms Tuesday night, it should bring them in Wednesday. The front will then stall as it passes south of us, and it may even wander back north, which means we can expect numerous, off and on showers and storms Wednesday and Thursday. Nothing severe is expected, but we might see a few storm-chosen backyards or creeks fill up with water though heavy downpours. Lightning will also feature for the storm-chosen.

The pattern appears unsettled Friday through the weekend. GFS and Euro models disagree. The GFS is dry, the Euro is very wet, so it’s reasonable to expect the truth to sit in the middle. It’ll be humid, creating clouds to toss us shade and keep high temps under 90. Classic early August, where storms scatter, leaving some dry, some wet, and making rainbows.

I will update the forecast (and include more graphics) tonight.