We’re starting off with a beautiful morning on this Sunday across the Tennessee Valley. Skies are partly cloudy (mainly just high, thin cirrus clouds moving in at the moment) with temperatures starting the day in mainly the lower 60s, although one or two spots are down to the upper 50s, and Decatur is still holding closer to the mid 60s. Clouds are increasing upstream to our west with widespread showers and storms back west of the Mississippi River into the Southern Plains. That activity arrives by mid to late afternoon in our area. Meanwhile, before then, we’ll have partly sunny skies today with daytime highs topping out in the mid 80s.
As those showers and thunderstorms move in by the mid to late afternoon, one or two of them may be marginally and briefly strong to severe. The NWS Storm Prediction Center has placed far western portions of our viewing area (from about Saltillo and Lutts TN to just west of the Shoals metro down to Russellville and Phil Campbell in AL westward) in a Level 1 of 5 risk of severe storms. This is a very low-end and marginal risk, but a few of the very initial storms that move in this afternoon may have enough instability to work with to produce a few 40-50-maybe 60 mph wind gusts or small hail. We do not expect a tornado threat to be an issue. This means that there could be a couple of short-lived severe thunderstorm warnings this afternoon. It also wouldn’t surprise me if they expand the Level 1 risk to include more of the viewing area, but if that happens, our forecast remains the same as we think this is an areawide threat for our region…. a low-end one, but one that includes the entire area, regardless of where the SPC risk is drawn. The main time window for a couple of these storms to possibly be strong will roughly be from about 3-4pm until about 7-8pm this afternoon / evening.
Here’s a breakdown of the timeline for today and tonight with our Baron high-resolution Futurecast model. We start the morning mostly sunny to partly cloudy and mild with temperatures quickly getting into the 70s by 8:00-9:00am if not a little before. Clouds thicken and increase going into the midday and afternoon, but with continued breaks of sun at times, we warm into the mid 80s across the area. After 3:00-4:00 this afternoon, widespread showers and thunderstorms will move in from southwest to northeast across the area. It’s at this point until about 7:00-8:00 in the evening that a few of these storms may be strong to marginally severe as discussed above. However, as we get closer to sunset, the combination of the initial round of heavy rain and the loss of daytime heating will act to stabilize the atmosphere. Rain and thunderstorms will continue well into the overnight off and on, but this loss of daytime heating and instability will switch the situation from an isolated strong storm threat to just off and on heavy rain and rumbles of thunder once we get past sunset and into the overnight. There may be some ponding of water on the roadways or even localized street flooding in low-lying and/or poor drainage areas, but widespread or more significant flooding or flash flooding is not expected today or tonight.
Scattered showers and thunderstorms from the overnight continue on into the morning to midday hours of Monday. They are not expected to be severe. Rain chances are actually highest in the morning, although a few hit-or-miss spotty thundershowers are possible through the afternoon into Monday night as well. Daytime highs on Monday once again climb into the lower 80s with Monday night lows staying in the mid to upper 60s with increasing low-level moisture and cloud cover.
The off and on rain and stormy pattern will continue for much of the week, with rain chances not dropping off until Saturday. However, rain chances are elevated the most once again Tuesday into Tuesday night, Wednesday night into Thursday morning, and then lingering showers into Friday. Temperatures will stay into the low to mid 80s for daytime highs through Thursday with overnight lows in the 60s to near 70 at times, but cooler air arrives for Friday and the upcoming weekend. Daytime highs Friday are back in the 70s, and we’ll range from the upper 60s to lower 70s this coming weekend with morning lows down into the 40s and 50s!
There is another lower-end severe storm risk across our area for Tuesday and Tuesday night. The Storm Prediction Center has our area split between a Level 2 of 5 and a Level 1 of 5 risk of severe storms. The main timeframe will be during the afternoon and evening hours. The primary threat of severe storms will be north of our area however. Locally speaking, the main concerns are once again a few isolated storms that may produce gusty winds, small hail, and localized street flooding. A threat of tornadoes with this wave of storms is not expected. While actual rain coverage Tuesday and Tuesday evening will be a bit more on the scattered to numerous side, the actual severe storm threat itself is very isolated, marginal, and lower-end.
That may not be the case for the wave of storms coming in Wednesday night, however. The Storm Prediction Center already has all of our area in the equivalent of a Level 2 of 5 risk of severe storms (they don’t do the 1-5 risk scale until the Day 1 through Day 3 outlooks, but this is the equivalent of a Level 2 risk), but there is the potential that some portion of the area may be upgraded. This threat is part of a larger-in-areal-coverage severe weather threat for Wednesday and Wednesday night threat stretches from the Ohio Valley all the way back to central Texas. While we may see a couple of isolated stronger storms with a wind/hail risk as early as the afternoon hours of Wednesday, the main timeframe for a more organized severe storm threat in our local area appears to be from the late evening/overnight hours of Wednesday into the predawn hours of Thursday. The main threats with this more organized wave of storms will be the potential for damaging wind gusts of 60+ mph, hail, and localized street flooding. However, unlike the lower-end storm threat later today and the lower-end storm threat Tuesday, this Wednesday overnight threat will also carry some degree of a tornado risk. The exact magnitude of the tornado risk is uncertain at the moment and will be dictated by whether the storms are more in a line when they arrive or whether they may be more in the form of cells or clustered, as well as how strong the low-level wind shear will be. We are uncertain about those factors at the moment and won’t have a good handle on them until probably some point on Monday at the earliest, but the overall severe weather setup does support at least some degree of a tornado threat across the area Wednesday overnight. We don’t want you to be alarmed or panic. There’s no need for that. This is spring in the Tennessee Valley. We face storm threats like this every single year! Just make sure that you stay aware of the forecast the next few days, have your safety plan figured out ahead of time, and have reliable methods of getting warnings if they are issued (including that will wake you up out of your sleep since this one is an overnight threat), and we’ll get through it together just fine!
We mentioned earlier in the discussion that rain clears out and temperatures get a little cooler for the weekend. This coming weekend is Mother’s Day weekend, and the forecast overall looks great! Daytime highs will be comfortably back into the upper 60s to lower 70s with mostly sunny skies for both Saturday and Sunday.
Looking into the extended range, it looks like this is the beginning of a shift back to below normal temperatures for a little bit that will carry us deep into the middle of May. The NWS Climate Prediction Center has our area outlooked for below average temperatures on both the 6-10 day and 8-14 day outlooks. That doesn’t mean we’re going to be actually cold or anything! We see no signs of a danger of a late season frost or anything crazy like that in our local area. However, this is a signal that we aren’t going to run face first into summer heat just yet, and that we are likely to step back into daytime highs that range from the upper 60s to the mid 70s for a while, with overnight lows back into the 50s… and a few nights here and there may be during into the mid to upper 40s. It will be a welcome break from the heat before we run headlong into summer!