A frigid Arctic high continues to build into Southeastern parts of the United States. This has allowed temperatures to plunge to well-below average values. The cold temperatures & low wind chills will stick around Monday night & Tuesday, which will help set the stage for light wintry precipitation.
The feature of interest that will generate lift, leading to light snow, is a rather potent shortwave that is diving southeast Monday evening. This shortwave is generating quite vigorous lift but with an Arctic airmass in place, the atmosphere is very dry. The one exception is the mid-layer of the atmosphere. This region is quite moist with this disturbance, which will allow snow flakes to develop and begin to fall. With the snow flakes having to survive a fall to the surface, many just wont reach the surface because the dry air will allow them to sublimate. However, a few will survive and should reach the surface beginning in southern Missouri & Arkansas Monday evening, then eventually spreading east in parts of Tennessee & northern Mississippi overnight Monday. By early Tuesday morning, the flurry threat will extend east into northern Alabama & northern Georgia as well as the higher terrain of North Carolina.
Most areas will only see an uptick in cloud-cover but a few areas will luck out and see light snow flurries. The best chance for accumulations will be across southern Missouri, northern Arkansas & the higher terrain of eastern Tennessee/western North Carolina.
Again, no travel issues are expected but enjoy the light snow if you’re lucky enough to see some and stay warm out there!
A severe weather outbreak is expected to impact the South late this week into the weekend. A potent upper-level storm system will dig into the Southwest late this week. Out ahead of this storm system, temperatures will climb 10-20 degrees above average with dewpoints soaring into the 60s & 70s. This airmass is unusually warm & moist (unstable) for early January.
As the storm moves east, it will spread high wind shear into parts of the South beginning Friday. This wind shear paired with the warm & moist airmass will allow thunderstorms to develop and quickly become severe on Friday. These severe storms will continue overnight Friday into Saturday as the system and associated shear advance east.
Friday, severe thunderstorms will erupt along the I-35 corridor in Texas & Oklahoma by late-afternoon. These storms will race east across eastern Oklahoma & eastern Texas during the evening hours on Friday. During the overnight hours Friday, storms will move into southern Missouri, Arkansas & Louisiana. Thunderstorms will produce tornadoes, damaging winds & large hail. The greatest severe risk Friday includes southeastern Oklahoma, southern Arkansas, western Louisiana & eastern Texas. It should be noted, all areas included within the Level 1, Level 2 & Level 3 risk categories have a chance to see severe thunderstorms.
The severe threat will shift east throughout Saturday. By early afternoon, the severe threat will exist across central Tennessee & eastern Mississippi. The severe threat will then shift east into the late-afternoon/evening hours for Alabama, western Georgia & the Florida Panhandle. Similarly to Friday, all modes of severe weather are expected. Tornadoes, damaging winds & large hail all possible.
A flash flood threat also exists. The greatest flood hazard will reside across Louisiana, Mississippi, Alabama, Tennessee & northern Georgia.
I’m currently keeping
a close watch on the small but noteworthy possibility of a winter event
occurring across parts of the South after January 15th.
If you strictly look analyze model data at the mid and upper levels of the atmosphere, you’d be tempted to believe that the pattern is complete garbage for wintry weather probabilities farther south. However, the GFS model has a ridge building into the Gulf of Alaska and Alaska and a trough downstream of that ridge just off the West Coast. Then, it has a broad ridge over the central U.S with another trough over New England. Overall, the mean-layer flow is pretty zonal across the central U.S. and Southeast. Ridging usually means warmer weather, but how is this different?
You must consider the
placement of these features aloft, and what will occur at the surface in
response. I drew some arrows to show the overall flow with a pattern like this.
Essentially, winds aloft go up and over the ridge, and winds also go around and
under the base of the western trough. As a result, confluence occurs over
western Canada. In response, surface high pressure develops over western
Canada, and if the high moves into the U.S., it funnels cold, Arctic air into
the U.S. due to the clockwise flow associated with high pressure in the
If a southern stream shortwave were to become embedded within the zonal flow and precipitation were to occur as a result, then it’s not entirely impossible to get some wintry precipitation (ice or snow) across parts of the Southern Plains and Southeast with this type of pattern.
Keep in mind that this
pattern needs to keep showing up in the models. Any minor changes in the
placement of these mid to upper level features can greatly change the outcome
of a forecast. I do believe there’s value in using pattern recognition to
consider the different possibilities using model data. Even if nothing occurs,
it’s still good to learn about what would happen under a given pattern.
Light snow is possible for parts of the Southeast on Saturday. A rather potent upper-level trough will dig southeast into the Tennessee Valley on Saturday. A piece of energy (lift) will rotate into the Southeast on Saturday via this trough, which will provide the lift needed for precipitation to develop on Saturday in the colder airmass. Precipitation will fall in the form of rain early Saturday before colder temperatures aloft and at the surface filter in.
These colder temperatures will allow rain showers to transition to snow showers across eastern Tennessee, far northeastern Alabama, northern Georgia and western North Carolina. There may even be a flake or two across far western parts of upstate South Carolina. The best window for snow showers will be Saturday afternoon into Saturday evening. The snow chances will hang on just a touch longer for the highest terrain of far eastern Tennessee & western North Carolina thanks to a touch of upslope.
Light snow accumulations are possible in northern Georgia with the best chance for accumulations above 2,000′. Up to 1″ possible above 2,000′ while 2″ possible above 3,500′. The higher snow totals will occur in the mountains of eastern Tennessee and western North Carolina where 4-8″ will fall above 5,000′. Lower elevations will see lesser amounts in Tennessee; 1″ above 2,000′ with 2-3″ above 3,000′.
No winter weather products are in place at this time but a Winter Weather Advisory may be needed for the higher elevations of eastern Tennessee and western North Carolina by Saturday.