(WMC) - Another winter storm will impact the WMC Action News coverage area Friday and this one has the potential to create travel problems during the day. A low pressure system will once again move east out of Texas and cut through the southeast. The low will kick an abundance of Gulf moisture into the area which will override cold air at the surface. The good news with this system is that temperatures will rise as the low gets closer to our area which will allow precipitation to transition to a cold rain by Friday evening. The problem will be from the time the precipitation begins until it makes the transition to rain. Let me explain my current thinking.
Friday morning will likely begin with a cloudy sky and temperatures in the low to mid twenties. There may be a few snow flurries in the area but I do not anticipate any significant precipitation. By late morning upper level moisture will begin to override the layer of cold air at the surface and scattered areas of sleet will begin to fall. I think we'll continue to see periods of sleet through midday into the early afternoon. By the afternoon the mid layers of the atmosphere will begin to warm allowing more liquid precipitation to fall into a thin layer of cold surface air that is at or just below 32 degrees. This is where the potential for freezing rain will begin.
Let me side step and briefly explain the difference between sleet and freezing rain. Sleet begins falling as liquid and then freezes into an ice pellet BEFORE hitting the surface which then just collects on the ground making walking outdoors or driving treacherous. Freezing rain falls through the atmosphere in liquid form and then comes into contact with a surface that is at or below freezing. This liquid adheres and freezes to any surface that it comes in contact with. It not only causes problems on streets and sidewalks but it can create significant ice build up on tree limbs and power lines and increase the potential for power outages as the weight of the ice brings limbs and lines down.
Right now I think we'll see more sleet than freezing rain.
Now, back to what I expect for the rest of the day Friday: Around 3 p.m. or 4 p.m. there will likely be a period of freezing rain that gradually transitions to all rain between 5 p.m. and 7 p.m. and continues as rain overnight along with gradually rising temperatures.
The above scenario is all dependent upon the temperature at the surface and a variance of one to two degrees plus or minus would either delay or accelerate the process. The latest NAM (North American Model) forecast model is indicating a tenth to a third of an inch of ice build up in the area before transitioning to rain late Friday. This would create problems on roadways in the area making travel difficult.
A WINTER STORM WARNING will be in effect from 6 a.m. Friday until midnight for all of west Tennessee including Memphis and Shelby County as well as northeastern Arkansas and the Missouri Bootheel. A WINTER WEATHER ADVISORY will be in effect for north Mississippi and eastern Arkansas along and south of I-40 for that same time period.