It's another fine warm day, although warm, across the Tennessee Valley. Just some scattered cumulus clouds in the sky, with plenty of sun otherwise. Temperatures are in the low to mid 80s areawide, within a few degrees of where we will top out at for daytime highs. We do have a decent southerly breeze though ahead of the big system out in the Plains and Midwest, but that system will stay to our west until Friday.
After our warm Wednesday afternoon, we drop into the 70s as the sun goes down this evening and clouds clear out. We look to drop into the mid 60s by daybreak on Thursday before clouds start to increase again from the west. We're headed for the low to mid 80s again on Thursday as broken clouds and some sun and southerly winds allow us to warm up ahead of the gradually advancing cold front over the Plains and Midwest.
Low pressure develops on that front as the main upper-level storm system heads east on Friday. That brings the front into our area during the afternoon and evening hours. Rain and thunderstorms will move through the area ahead of the front from about early/mid afternoon until the late evening. The cold front moves through overnight, with much cooler and drier air settling in for the weekend with northerly winds and clearing skies on the back side of the front as high pressure settles into the area. After highs being in the 80s all week this week, we are in for a big shock to the system. Daytime highs over the weekend will only be in the mid to upper 60s, with morning lows by Sunday and Monday mornings in the low to mid 40s!
As the front moves in Friday afternoon and evening, there may be a few strong thunderstorms ahead of it though. We will have to watch this pretty carefully. We will have adequate instability (fuel) and upper-level support for strong or maybe even severe storms. However, the strength of the low-level shear (spin) is in question. It looks higher from I-40 and northward through middle Kentucky, where the risk of severe weather seems to be a bit higher. However, if we get increasing confidence that our low-level shear will be adequate, we may have to talk about a risk of severe storms locally from the mid afternoon until roughly midnight on Friday night. There are just too many questions now for that type of talk, but we are watching things carefully and will provide updates as details become more clear and certain.