The National Weather Service in Huntsville issued a FLOOD WATCH for North Alabama and Southern Tennessee from 6 AM Wednesday to 6 PM Thursday. A large amount of rainfall forecast in that time frame could cause flooding: especially in areas where the ground is already saturated and rivers are already running high. Rivers like the Flint, Paint Rock, Elk and of course the Tennessee are already expected to be in minor to moderate flooding by Thursday morning.
How much rain this week? The ‘official’ forecast from NOAA’s Weather Prediction Center (WPC) shows roughly 2” to 4” through Thursday afternoon. A few communities will ‘overachieve’ that range and get as much as 4” to 6” in a 30-hour period from midnight (12AM Wednesday) to noon Thursday.
This is the most significant flood threat we’ve had since Christmas Day 2015. That doesn’t mean an ‘exact’ repeat of that day; this isn’t that same kind of set-up. Most of that day’s flooding came from slow-moving thunderstorms that dropped 3-7” of rain in a few hours. The Wednesday-Thursday rainfall comes over about 30 hours. That means the water may not rise as fast, but it could slowly rise as high in a few places. Be on the lookout for flooding!
What about severe weather? Severe storms seem very unlikely in North Alabama and Southern Tennessee at this point. Most of the energy for thunderstorm development (the fuel, or ‘CAPE’) stays southwest of us. Some thunderstorms are possible, but we don’t expect them to have the kind of support to be ‘severe’ (58 mph winds or higher, hail larger than a quarter, and/or tornadoes).
Drying out for Friday and the weekend: Ready for some good news? Rain moves out by Thursday afternoon, and drier, colder air blows in for a few days. ‘Colder’ is relative: not like January, but colder than it’s been for most of February.
Expect a sunny sky Friday. Chilly air in place keeps the temperature in the mid-50s in the afternoon. We’ll see some frost Saturday morning, and some spots will get a light freeze with lows around 32ºF. Saturday and Sunday look like great days: cold mornings, mild-to-warm afternoons, and almost a fully-sunny sky the whole way during the day!
More rain next week: Be thankful for a dry weekend, because next week starts out wet. Rain becomes likely again on Monday and Tuesday: some of it locally-heavy with more than 1-2” possible.