Early Sunday Morning Update

After reviewing the 00z and 06Z model data set, it still looks like there is a chance of some accumulating snow over parts of North Alabama tomorrow morning.

The key to the entire event is the degree of evaporative cooling. With dewpoints in the low 20s at the onset of the precipitation, it does look like the lower column of the atmosphere will ultimately be cold enough for some snow. Current observations show actual dewpoints in the 17 to 22 range right now.

Having said that, the 06Z models have come in a little warmer for the I-20 corridor.

The 06Z NAM shows 0.30" of liquid for Birmingham from about 4:00 a.m. through 12:00 noon tomorrow. IF that comes down as snow, the standard conversion could mean about 3 inches of snow. But, the parameters look a little warm for snow in Birmingham on this run.

Here are some values at mid-morning, when much of the precipitation will fall:

2M temp: 34.6
1000-500 mb thickness: 5445 meters
1000-850 mb thickness: 1309 meters
850 mb temp: 3.0 (C)
950 mb temp: 0.0 (C)

Yesterday's 12Z NAM run had Birmingham's 850 mb temp (about 5,000 feet) colder than -3 (C). That is a significant warm-up on this run.

The surface low position on both models generally runs from Mobile to Dothan during the day.

Here is the bottom line:

I think there is a chance of one to two inches of snow along and north of a line from Hamilton to Oneonta to Jacksonville to Heflin.

Keep in mind the ground is still relatively warm from the recent mild weather, and many roads will simply be wet. However, as always in Northeast Alabama there will be some cold pockets where temperatures will be a little below freezing, and some bridges could be pretty slick early tomorrow morning.

For Tuscaloosa/Birmingham/Anniston, some snow flakes are certainly possible, but for the moment the thickness values really don't support a big snow event. Could very well be mostly rain, with temperatures in the mid 30s.

IMPORTANT POINTS:

*We really don't have any TRUE Arctic air in here yet... this is modified Polar air. The really cold air won't get in here until late in the week. For snow fans, I think there will more opportunities for snow when we do indeed get really cold. The 06Z GFS paints a snow threat right now over the coming weekend over the northern half of Alabama (on Saturday). This is a cold and unsettled pattern setting up for the next few weeks.

*Snow forecasting in Alabama is difficult; trying to define a rain-snow line, and a line where accumulation will begin, is very difficult in a system like this. This forecast could change later today as the new 12z model data rolls in and the system actually begins to take shape this evening to the west.

Brian Peters will be along a little later this morning with his discussion and a map discussion video update.

I will be headed to Hunter Street as usual shortly to teach in our Outfitters 2:52 children's worship services... Then I will be back in the saddle and post some updates here through the afternoon and tonight on forecast ideas.

Stay tuned..