Winter Weather Threat

Not even a day removed from a severe weather episode, our area will be the target of a storm system poised to bring winter weather tomorrow. The synoptic setup for this event is not complex at all. An upper level low over southeast Texas and a coupled jet structure has initiated the development of a surface low pressure center just south of Mobile Bay. This surface low is forecast to move northeast and be located near Charlotte, NC tomorrow night. As this low lifts to the northeast, it will begin pulling down a shallow, modified arctic air mass on the backside of the low. Not surprisingly, this shallow air mass has been poorly forecast by the models for the last 36 hours, and I feel like surface temperatures will be cooler than forecast even without any dynamic processes in play.

Isentropic upglide, PVA, and the right rear quadrant of a jet streak are causing a large shield of rain that is soaking parts of Louisiana and most of Mississippi tonight. This steady shield of rain will continue to expand and shift northward overnight so look for rainfall amounts to exceed an inch overnight. The precipitation will stay all liquid overnight as forecast soundings from all models do not show any type of frozen profile (large melting layer, warm temperatures in the melting layer, and above freezing surface temperatures). Temperatures won't change much tonight and will likely be around 38 before sunrise.

Heavy rain will continue to fall for a few hours after sunrise, but then things get really interesting late tomorrow morning and afternoon. Temperatures will likely drop after sunrise with the approach of the upper air low. This low will begin to move to the northeast and the main core should remain to our south. These upper level lows are notorious for generating their own cold air, and snow does not appear to be any question for Central and Southeast Mississippi. Given the close proximity of the upper low, a low/mid level convergence zone will develop and will lead to localized higher snowfall totals. It's very difficult to predict exactly where this band of heavier snow will set up, but it appears most likely to run in a direction from southwest to northeast and Starkville could be very close to its northern fringe.

Although the upper low will not be directly over us, very strong upward motion will cause dynamic cooling to occur. This will allow the temperature profile to cool enough for wet snow to begin after 11 a.m. in Starkville. Surface temperatures will likely remain just above freezing so it may be initially tough for snow to stick on the warm ground. However, given the impressive vertical motion forecast by all the models, a burst of heavy snow is likely, which will likely allow a thin layer of snow to cover the ground. When this occurs, it should be no problem for additional snow to accumulate on the surface. Additionally, with a heavy burst of snow, the surface temperature should begin dropping and be around 33 by early afternoon. The heavy snow may continue through most of the afternoon before tapering off around 5 p.m.

Snowfall totals are difficult to predict given how long it will take for the snow to first cover the warm ground. My best guess is probably close to an hour, but with almost five hours of snow, we could receive 1-3" and possibly up to 4" if the northern fringe of the heavy snow band moves through. I'll forecast 2" of snow in Starkville.

One aspect of this storm that is not getting a lot of attention is the potential for strong winds tomorrow. As the surface low moves east, a tight pressure gradient will allow northwest and northeast winds to gust over 30 mph at times tomorrow. This will make temperatures feel like they are in the 20s for most of the day! Be sure to cover your skin if you'll be outdoors for any extended period of time.

This will be the first true snow I have experienced in Starkville and I've been here over 8 years! It's going to be an exciting day tomorrow. Check back tomorrow morning for a new update on the forecast.