Southern Snow!

The latest numerical guidance is beginning to converge on a scenario that would produce snow for parts of the South, parts of the Tennessee Valley, and parts of the Ohio Valley late this week into the weekend. A upper-level trough will dig southeastward across the Southern Plains late on Thursday. As the trough begins to move out of the Southern Plains, it appears it will close off. This is supported by the European, the Canadian, and the NAM. The GFS actually does not close off the trough and is very fast with movement. This is the outlier, and many of the ensembles do not support the operational run. This will be tossed for now, and I will use the NAM and European as tools for this forecast. These two models appear to have a good handle on the evolution of the upper-level low.

Upper-Level Low (Friday Morning)

As the upper-level low develops south of the Ark-La-Tex vicinity, it will begin to deepen and wrap moisture around the northern and western side of the low by Friday. This is the cold side of the system, so precipitation will likely fall as sleet and snow in this area. This will place eastern Arkansas, northern Louisiana, northern Mississippi, and western Tennessee in a favorable area to see wintry precipitation. It is possible, depending on the location and track of the upper-level low, that wintry precipitation chances will extend into parts of Alabama and the rest of Tennessee by Saturday. Sleet, followed by snow is likely in the Ohio Valley by Saturday into Sunday.

Future Radar (Friday Evening)

Future Radar (Saturday Morning)

Looking at modeled forecast soundings, surface temperatures are initially marginal, and there will be an elevated (but thin) warm layer. This will likely cause a period of sleet. But dynamic cooling will eventually take place—leading to snow.

Accumulations are possible, but too hard to forecast at this point. Depending on the deepening of the upper-level low, and the track, it will have huge implications on snow amounts. The transition period will be important too. There are still too many uncertainties with the changeover from rain, to sleet, then to snow will occur. The deeper the low: the more snow. The faster the changeover: the more snow. These are variables that we cannot accurately forecast at this point. I will say, however, some guidance is hinting at a TROWAL developing. TROWALS are known for producing heavy precipitation. Wherever this feature sets up, if it does, some areas could see a surprise. I will have updates as needed.

Firsthand Weather’s Preliminary Forecast