We will have to dodge a few showers or thunderstorms through about 8:00 PM. They will be few, but those that develop can become strong. Threats from stronger storms will include 50 mph winds, gusting up to 60 mph, brief heavy bursts of rain, and frequent cloud-to-ground lightning. More of the Tennessee Valley is likely to miss the storms than actually get storms this evening.
The heat may be the bigger issue for us. Heat indices were around 105 degrees this afternoon. The heat index won't drop below 90 for many of us until almost 9 PM. The heat index will be back up to near 100 by noon Thursday. It can climb toward 105 again before scattered showers and a few thunderstorms help to ease the heat a bit.
Showers and a few thunderstorms will be scattered across the Tennessee Valley on Thursday. Everyone is fair game, but not everyone will actually get any rain. Areas south of the Tennessee River are in an area that may be more favored for the showers and storms. The showers and thunderstorms will begin developing between noon and 2 PM. They will increase in coverage, gradually growing more widespread, through about 6 PM, then they'll fade to an end by around 8 PM.
Keep in mind that any time we have thunderstorms forming in 90 degree heat, a stray severe thunderstorm is always possible. Be ready to move to safety if that happens. With the heat, be sure you stay hydrated by drinking plenty of water. Don't overdo it outside, and take frequent cool breaks if you will be outside for long periods of time.