Morning update on snow storm

Looking at all 12Z models now.  The NAM has come in with some very impressive snowfall amounts (see James’ post below), and the models have generally trended toward a surface low a little farther south, meaning a colder atmosphere overall, and less of a warm layer to produce rain that would freeze on impact, producing an ice storm.

It looks like we may have to move the “sweet spot” for the heaviest snow accumulations a little south this afternoon.  We don’t make big changes based on one model run, but I’d say the most likely area for heaviest snow extends from BHM to HSV, instead of Cullman to south TN.   One concern is that there is still some warm air between 4,000 and 8,000 feet, and for snow to form (instead of supercooled water drops), the temperature needs to be below 23 degrees aloft.  That should be the case, as most of the dynamic lift with this system is between 10,000 and 20,000 feet, but NCEP (Washington “think tank” of NWS) is still concerned about icing in central Alabama, especially BHM to MGM. 

Bottom line…precipitation will begin, probably as snow (at least in areas from Clanton north), late Sunday afternoon, then really pick up Sunday night.  We expect snow amounts in the heaviest snow band, wherever that sets up, of 4 to 8″, with 2-4″ either side of it.  Some of the snow could change over to freezing rain early Monday morning, producing icing.  We will have to watch the temperatures aloft carefully tomorrow as the cold air comes in.  Even if it is all snow, the weight of it may cause some power outages.

If you have any plans to travel on the roads in north and central Alabama, you should try to do that before about 8 pm Sunday (+/-).  Travel may be impossible Monday (and maybe Tuesday).

We are now 95% confident that there will be a major winter storm in Alabama.  I’d give it 90% that it shuts down the interstates in BHM.

Category: Alabama's Weather