The counties highlighted in blue are under a winter storm watch through 6 pm tomorrow.
The important cold upper low has started to develop and move in Texas this afternoon. As JP and I have been saying, upper level lows are very difficult to forecast. It looked yesterday like most of the precipitation would come in before the cold air, and we would only get 1" of snow, with most of that staying on the grass, cars, etc. But, a minor change to the shape of the upper low as it moves through here looks like it may cause more snow.
The upper low brings cold air with it, and the lower atmosphere will become cold enough for snow from west to east across Alabama tomorrow morning. The lowest 10,000 feet of the atmosphere will be cold enough for snow in BHM starting around 9 am. However, at that time, surface temperatures will still be way above freezing.
If the models are finally now correct (still questionable with a cold upper low), snow will continue into the early afternoon hours. With snow falling, it not only brings colder temperatures down with it, but when it melts on the ground that uses up heat. It will likely drop to near freezing in BHM for 2 or 3 hours in the afternoon, allowing some snow accumulation. Most of the snow accumulation will still be on grass, etc. It looks like some places will get 3" (or more) of total snowfall, but a lot of it will melt initially and not accumulate. However, if enough snow falls, temperatures will drop and snow may start to accumulate on some bridges, causing travel problems.
We need to emphasize that there is still uncertainty with the forecast. This is not the classic setup for heavy snow in Alabama. However, that does not mean that we will not get 1-2" of snow tomorrow, right in the middle of the day, and there could be some slick spots on bridges and in higher elevations. Areas in east Alabama may get more snow, maybe 3" on some mountaintops. See the blog post below from Wes and JP.
We will continue to monitor this rapidly changing situation. I will have another blog post here by 930 pm, and JP will have an update on Fox 6 news at 5 pm.
Dr. Tim Coleman
Fox 6 Severe Weather Expert
My twitter - timbhm