We're starting off relatively mild on this early Thursday morning, especially compared to what is coming. Temperatures across our area are in the mid to upper 40s this morning, with a few folks in southwest Tennessee to northeast Mississippi not too far from 50 degrees. Clouds have hung tough overnight, and this has acted as an insulating blanket. Combine that with the southerly winds that are picking up, and we're a good bit milder this morning than what we were just this time yesterday. That will change quickly over the next 12 to 18 hours though!
We look off to the northwest, and the arctic cold front is already slicing sharply though Kansas, Oklahoma, Missouri, and the Texas panhandle this morning. It's 43 degrees in Little Rock and the DFW Metroplex, but it's only 3 degrees in Wichita, Kansas! Wind chill values over the central and northern Plains are way below zero, and if you look carefully over southern Montana, our graphics system doesn't even have color palette values to display how low the wind chill is there! While we won't see the numbers found in places like Montana, Wyoming, and the Dakotas, bitter cold will be making its full presence known in the Tennessee Valley by the early evening!
Futurecast has cloudy skies in place at 6:00am with temperatures areawide in the low to mid 40s. Since the temperatures between now when I'm typing this blog and 6:00am likely won't move much at all, it's very possible Futurecast may be running 3 or 4 degrees too cool with temperatures. Keep that tidbit in mind. That may be important to the forecast temperatures by Friday morning. As we head forward through the day, mostly cloudy skies and southerly winds continue. We may see a brief peak of sun here and there though. Daytime highs look to reach the lower 50s areawide today, but a few folks in north Alabama might briefly get close to the mid 50s.
The arctic cold front comes racing toward our area by late afternoon though! By 5:00, Futurecast has the cold front knocking on the door of our far western counties, and then crossing the U.S. 43 corridor of middle Tennessee and north Alabama in the 6:00-7:00 timeframe, and crossing I-65 by 7:00-8:00pm. Give or take a little time with that, but high resolution models seem to be in good agreement with that timeframe. As the cold front crosses your area, temperatures will RAPIDLY drop. Futurecast has the U.S. 43 corridor, for instance going from the upper 40s to near 50 degrees at 6:00 to the upper teens and lower 20s by 7:00pm!
There will be a period of rain showers ahead of the front during the afternoon, but as the cold air immediately rushes in, this will quickly transition over to wintry precipitation. Because the cold air the first few miles behind the front will be shallow, there will be a 15 to 30 minute period where the precipitation may be a mix of sleet or light freezing rain. However, as the cold air rapidly deepens, the precipitation should change over to all light to moderate snow within the first hour of the cold front passing through. That looks to happen between 6:00-7:30 this evening across the heart of our coverage area, from west to east. Then, we will see a few hours of light to occasionally moderate snow and snow showers before that shifts east by 9:00-10:00 at the latest, based on latest high-resolution models. We don't expect this to be a big snow accumulation in our area. Read that again. We don't expect this to be a big snow accumulation in our area. However, with how rapidly temperatures drop into the teens (and then keep dropping overnight), it is very possibly that any remaining moisture on the roads, whether it is from afternoon shows or from evening wintry precip, may flash freeze on exposed surfaces. This may cause icy / slick spots on roadways and bridges, even surface roads, and that may lead to some sketchy travel in spots tonight into Friday. While the 30-40 mph wind gusts expected may indeed help to dry some of this moisture and reduce how widespread icy travel conditions may be, I don't think it will completely get rid of the slick spots. Expect some dicey travel tonight into Friday.
High resolution model guidance is in good agreement this morning on this being a light snow accumulation event for our area. The general idea shown is for there to be a dusting to half inch in most areas, with better chances of an inch or more of snow being mostly north of Highway 412 in western/middle Tennessee. The only exception to that is that the models are picking up on a small scale enhancement over portions of Wayne and Lewis Counties. While that is too small scale for us to have enough confidence in until the snow band actually sets up on radar this evening, I can't rule out a locally enhanced area like that where totals may be near or just slightly over an inch. It may not be specifically Wayne or Lewis Counties either IF it does happen, but that's where models are consistently showing it. For the majority of us, a good little dusting to a half inch of snow accumulation looks most likely.
This matches up well with our actual FORECAST that we have had out there since midday yesterday. The majority of our area looks like it will see a dusting to maybe half an inch of snow, with better chances of totals nearing an inch being north of Highway 412 in Tennessee, although we will have to watch out for a small scale enhanced area like we talked about above. Because of the rapid drop in temperatures though, it will only take a dusting of snow to cause slick/icy spots and travel issues that may last through tonight into at least part of Friday.
The National Weather Service in Memphis has placed southwest Tennessee and north Mississippi (including Hardin and Tishomingo Counties in our viewing area) within a Winter Weather Advisory. This is for the potential for flash freezing late this afternoon and this evening, either from the leftover moisture from afternoon showers or from any light snow accumulation. The Nashville office is using their Winter Weather Advisory to highlight where they think an inch or more of snow may accumulate, and that is why it does not include southern middle Tennessee. Similarly, the Huntsville NWS office would be using theirs for the same kind of snow totals, and since they don't expect that, they don't have an advisory in place for north Alabama.
Regardless of what any snow may or may not do, the big story is and has always been the major cold air and the dangerous/potentially life-threatening wind chills we expect across the area. That's why there remains a Wind Chill Warning across our entire viewing area for tonight through at least noon on Friday for middle Tennessee and through noon on Saturday for north Alabama. It's very possible the Tennessee counties may get an extension into Saturday in future updates from the NWS. Wind chill values of -10 to -20 are a good bet across these areas, especially tonight through the first half of Friday, and they may stay below the zero to -10 range right on into Saturday. This is the type of cold that can cause frostbite in only half an hour if you aren't well-protected, and this type of cold is life-threatening to people and animals that have no shelter from it.
The entire weather community has been talking about this non-stop for an entire week now, but here are some general tips for you to go through to prepare yourself, your friends and family, your pets and animals, your home, and your vehicles for the coming cold weather. You only have about 12 or so hours from the time this blog discussion is posted to get these things done. This is nothing new. These are basic, common sense things, but they serve as a good reminder for what you need to think about in order to prepare for the coming cold temperatures.
Once temperatures drop below freezing early this evening, we stay below freezing non-stop until some time for a short period Monday afternoon. That is an 80-90 hour period where temperatures are non-stop below freezing! That is a pipe bursting type of cold. In similar cold waves in the past here in the Tennessee Valley, even building sprinkler systems have had busted pipes if those buildings aren't well insulated! The good news is that the cold air doesn't stick around forever. By early to mid week, we are in a first warming trend. By Wednesday, we will be getting close to 50 degrees for a daytime high again, and I can't rule out 60s by next weekend and the start of the new year! It can sometimes get really cold here in the Tennessee Valley, but when it does, it usually doesn't stick around for too long. After our showers this afternoon and the light snow this evening, we are dry through at least the middle of next week, including a dry and quite (but cold) Christmas weekend.