Right Now/The Setup:
Confidence is increasing for wintry precipitation to impact parts of the Southern Plains, South, and Southeast beginning tomorrow in parts of the Southern Plains and continuing into the weekend. Models are in relatively good agreement of the placement of synoptic features for this setup, but there are still a few questions that I will try to iron out in this discussion.
The system that will bring wintry precipitation to southern parts of the country is currently located across the Pacific Northwest. This closed upper-level low will dive southeastward and slowly open up as it approaches the Southern Plains. Ahead of this approaching system, a surge of arctic air will advance southeastward, which will set the thermal profiles for wintry precipitation. As the trough digs into the South and moves away from the Southern Plains, a surface low may develop along the north-central/northeast Gulf Coast. This will setup precipitation chances for parts of the South and Southeast.
An area of snow will begin to develop Thursday night into Friday in the Texas Panhandle and central Oklahoma before advancing east-southeastward. This band will eventually impact most of central and southern Oklahoma, northern Texas, and develop eastward into Arkansas, northern Louisiana, and into northern Mississippi/Alabama (more on these areas later in the discussion).
It is important to note, this band of snow will develop into response to lifting associated to frontogenesis. The reason I mention this is because it’s extremely difficult to forecast the exact placement of this frontogenesis. It appears the frontogenesis with this arctic boundary will be pretty significant, which could lead to adequate lift to dump moderate snow for some areas. Typically this type of setup can lead to decent snow amounts for some areas with a tight gradient to no snow just over a small distance. I will continence to monitor the evolution of this band and adjust the forecast accordingly dependent upon where this temperature gradient sets up. It should be noted, the forecast soundings across the Texas Panhandle, Oklahoma, Arkansas, and northern Texas are conducive for high snow ratios (greater than 10:1), which could lead to a quick few inches-especially in Oklahoma and the Texas Panhandle. Right now, it appears the heaviest snow should be just south of the Oklahoma City Metro and remain well north of Dallas; however, these Metro areas will likely see light snow/flurries. It should be noted, some of the short-range guidance is hinting at an area of very light freezing drizzle developing in response to an area of isentropic lift across parts of the Texas Hill County-just outside of Austin. This will need to be monitored early Friday morning because it could make bridges and overpasses slick.
A second chance for light snow may evolve across southern Oklahoma, northern and eastern Texas, southern Arkansas, and pars of Louisiana late Friday as the trough moves across the area. The trough will aid in enough lift to generate some light snow flurries, but moisture is meager at best, so any snow that falls will be very light at best. Locations further southeast, in east and southeast Texas, may see a few sleet pellets looking at the latest forecast soundings. It’s possible the far northern parts of Houston may get in on the ‘fun.’
South and Southeast:
The South and Southeast will see wintry precipitation as well. The aforementioned region of lift associated with the frontogenesis across the Southern Plains will also be a variable in the South. A narrow band of precipitation will develop across southern Arkansas, northern Louisiana, into northern Mississippi, and northern Alabama. As mentioned earlier in this discussion, these setups are extremely difficult to forecast in regards to where the most intense zone of lift develops in response to the significant temperature gradient above our heads (around 700mb)—the surface cold front will be well south into Texas but the front slopes so essentially which creates a unique position of the 700mb temperature gradient in which is the zone the band of snow will develop. Areas beneath this band of snow could see a quick accumulation while areas just outside of this band see nothing—the gradient will be tight. Right now, it appears Birmingham may see snow from this initial band of snow.
As the trough moves east of out of Texas, a weak surface low may develop along the north-central/northeast Gulf and begin to move off to the northeastward. The evolution of this low, if it develops, is still uncertain at this point (and we are a couple days out so I will continue to iron out the details of this feature later in the week). If the low develops, it may wrap some additional moisture into the cold air across the Southeast. This would give Georgia, South Carolina, and North Carolina a chance of snow and a wintry mixture for areas closer to the coast. It is possible an area of enhanced accumulations may occur if the low deepens as it moves off the East Coast. This will be closely monitored. There area many uncertainties with the onset of precipitation, temperature profiles, and the northward extent of the precipitation axis. Small deviations in these variables, or a prolonged mixture of sleet, could drastically impact accumulations.
Preliminary Wintry Precipitation Forecast:
Below is my current thinking on which areas have a shot at wintry precipitation, and which areas have the best chance to see accumulations. Please note, confidence is higher towards the Southern Plains since this event is about 24-36 hours out, but confidence decreases further east. Forecasting wintry events in this region is extremely hard, and accumulations this far out is highly susceptible to changing—this may need adjustments tomorrow. I just wanted to generate a map in order to create a heads up in case the frozen stuff begins to fall in your backyard.