We continue to track the potential development of Freezing rain, sleet or snow for parts of the Tennessee Valley early Friday morning. Everything depends on the the cold air holding in place while the moisture moves over the top of the cold air. The following graphics represent the RPM forecast model we use in the WAFF 48 Storm Tracking Center.
The setup will begin as colder air arrives Wednesday night behind a cold front. This front will also bring a chance for some rain as it moves through. Temperatures will remain above freezing as this happens so no problems are expected Wednesday night.
The colder air will move in behind the front and the wind will remain out of the north and continue to bring in cold air. Temperatures drop into the 20s by Thursday morning.
Overnight Thursday into Friday a warm front will begin to lift north into the area. It doesn't look like this front will make it all the way into North Alabama. A southwest wind will develop higher in the atmosphere and this will bring moisture over the top of the cold air at the surface over the Tennessee Valley.
Evaporative cooling will take place as the moisture falls into the Arctic Air. This process cools the lower levels of the atmosphere and creates freezing rain and or sleet. There could also be snow. The red warm front stays south of the area for the duration.
By 10am most of the moisture begins to leave and track east. This model run shows about 4-6 hours of freezing rain/sleet or snow possible early Friday morning.
Keep in mind this is a model run and a trend we will be following. Some other forecast guidance has it warming considerably more. However given the extend of the arcitc air to the north at this time a colder solution is more likely.
We will continue to monitor this developing, potential, winter weather threat.
WAFF 48 Storm Team
We Track Storms