2/27 - 4:15pm - Two Shots of Severe Weather This Week
This will certainly be an active week across the Southeast as two storm systems cause trouble for many. The first of these severe weather events will affect West Tennessee and North Mississippi on Wednesday and the second should move through on Friday.
At this point it looks like we'll be tracking storms moving out of Arkansas into West Tennessee and North Mississippi on late Tuesday night after a few showers and possibly a storm pass through during the day on Tuesday. While these storms could have some potency over Central Arkansas, the thinking at this point is that they will weaken overnight as they lose the heating of the day. The best wind shear for these storms will be in the Jackson, TN area as they move through on Wednesday morning into the early afternoon ahead of a cold front, but without much of the needed instability that daytime heating helps to generate the storms shouldn't be too intense. They may very well reach severe limits with some wind and hail, but I think the worst of the storms will be more in Middle Tennessee where they'll have time to re-fire during the heating of the day. The Storm Prediction Center has 30% Slight severe weather risks over Arkansas into extreme West Tennessee on Tuesday and then has the same risk area in Middle Tennessee/extreme Northeast Mississippi on Wednesday. The worst severe weather will effectively leapfrog most of West Tennessee according to these two outlooks, and that looks like a fair forecast right now given the timing of the storms over the region.
Further south in North Mississippi the situation should be about the same, but with a little less wind shear support for severe storms and a later timing for them to move through (later Wednesday afternoon) since the cold front will stall near the MS/TN border for a while during the day (see left image from the 12 NAM). The NAM and GFS models agree that North Mississippi will have higher dew points (more moisture) than West Tennessee, but without great wind support this shouldn't lead to a noticeable increase in storm severity. I should point out that both locations could see a possible isolated tornado or two, but this should be a very low chance given the lack of good low-level wind shear.
Friday's severe weather event is not a clean-cut as Wednesday's is at this point, but it's looking more and more like this one will feature more intense storms. Another cold front passing through on Friday night will provide a focus for what could be a couple lines or clusters of storms. Right now the GFS and European computer models agree that this will likely not be a tornado outbreak because of the lack of low-level shear much like Wednesday's event, but the two models can't agree on how much moisture makes it northward from the Gulf. The GFS has 65 degree + dew points making it all the way into West Tennessee on Friday whereas the European is not as optimistic. This also plays into who sees the best instability too, so it's not clear right now as to who will see the most severe storms on Friday. It is safe to say that West Tennessee and North Mississippi may have to deal with high winds and maybe even some hail on Friday, and it will likely be more intense than Wednesday based on current data.
Southeast Severe Storms Symposium
To those who are attending the 10th Annual Southeast Severe Storms Symposium at Mississippi State University on Friday and Saturday, we will go on as planned even if there is severe weather in the region. While many meteorologists who will be presenting may not be able to attend because of the risk for severe weather in their respective coverage areas, we should be able to have most of them present their sessions to the symposium via Skype. I'm leading a group of meteorology students who will be live tweeting the symposium on the official Southeast Severe Storms Symposium Twitter account @SESSS12. Be sure to follow us!