A closed upper low is expected to move across the area on Thursday. The closed upper lows are cut off from the main flow, and are very unpredictable. Cold air causes the low, and then dynamic cooling due to the circular flow cools the air further.
Upper-level lows are usually associated with precipitaion. Where exactly in the low will be the big question. Temperatures in the lower atmosphere become cold enough for snow in Birmingham Thursday morning, and stay that way all day. However, the system does not have that much moisture to work with, and as cold air moves in, air tends to flow downhill, drying up precipitation. So, it does look like we'll have some rain Wednesday night that could change to snow on Thursday during the day. But, it looks like the heaviest precipitation will be ahead of the cold air. That's hard to know for sure, since these are so hard to forecast.
With ground temperatures warm from recent 70 degree weather, and surface temperatures likely staying above freezing all day Thursday, we do not expect significant travel problems even if it does snow. Someone in central Alabama could get 3" of snow out of this, mainly on grassy areas. But, there are always bridges, and if the snow is heavy enough for a little while, they could get icy. The main time for snow will be 5 am through 1 pm Thursday.
Overall, this is not a classic set up for heavy snow in Alabama, and it probably will not be a big deal. But, since a few areas may get 1" of snow, we'll watch it carefully. Things could change fast.
Dr. Tim Coleman