FUYC-170x65
Jack’s

Snow/Wintry Mix….Again??

Posted on: 2:47 pm, January 22, 2013, by , updated on: 03:30pm, January 22, 2013

Computer models continue to hint at the potential for some wintry precipitation for the second half of the work week. The amount and impacts look to be less than last week, but due the inconsistency in the model data, the specifics of precipitation type and amount are still in question.  Farther north towards Nashville, will be the best potential for some wintry precipitation, so if you will be traveling there for the weekend, it is important to be prepared for possibly some not so pleasant traveling conditions and slick spots on the roadways.

A frigid arctic air mass has settled into the Tennessee Valley over the past 24 hours, with highs today only in the 30s.  The roller coaster ride of temperatures will continue, as our area gets impacted by a two more systems through the end of the work week.  With high pressure to the east by Wednesday afternoon, warmer temperatures are expected, with highs reaching into the mid, to possibly upper 40s.  A quick moving upper disturbance will clip the area Wednesday afternoon and night, bringing with it a small chance for some patchy, light rain.  A few of the higher elevations along the Cumberland Plateau may get a few snow flurries, but no substantial wintry precipitation is forecast for the Tennessee Valley.  Farther north towards Nashville in central and northern Tennessee, that’s where things could get a little dicey, with the potential for a freezing rain/sleet/snow mix. Though the threat remains low. Below are two graphics from the National Weather Service in Nashville, Tennessee that do a good job of highlighting the winter weather potential for Wednesday night and early Thursday and a better chance for wintry precipitation for that region on Friday.

Nash1

Nash2

Early Friday a surface low will drags a cold front across the Tennessee Valley, with the chance for rain and possibly a change over to a wintry mix/snow as cold air rushes in on the backside of the system.  Computer models are very inconsistent with the impacts of Friday’s storm system, below is an example showing three different computer models; the GFS, ECMWF and the GEM Friday evening.

GFS

ECMWF

GEM

The GFS is the warmest of the models shown here, with the NAM (not shown) very close to the GFS, showing an all rain event for the Tennessee Valley and even northward towards Nashville (central/northern Tennessee).  ECMWF has the colder air dipping farther south, with the GEM being the coldest and wettest of the models.

So what do we expect for the Tennessee Valley?  Only very spotty showers Wednesday afternoon into early Thursday (not everyone will likely see rain). Farther northeast in the higher elevations of the Cumberland Plateau, a few snowflakes are possible. Friday, expect showers to start, with a possible change over to a wintry mix or light snow as cold air rushes in on the backside of the system.  The threat for wintry precipitation looks marginal and little to no accumulations are expected at this time, with the best chance for any accumulation being in the higher elevations of Northeast Alabama and adjacent southern, middle Tennessee.  With that being said, below the RPM wants to paint an icy picture for Friday morning and afternoon, with the pink indicating light freezing rain/sleet mix, which could cause icy roadways, this is something we will have to watch.

rpm

Below is a graphic from the Hydrometeorological Prediction Center, showing the 24-Hour Probability of freezing rain accumulating greater than, or equal to 0.01″, between Thursday and Friday evenings. It shows the highest probabilities for accumulation west of I-65.

freezingrain

As of right now, only expect a small chance for wintry precipitation Friday, but expect changes in the forecast as models come into better consensus and details become more clear.  No matter the amount of wintry precipitation we receive, there may not be enough time for roads to dry Friday night once the cold air really settles into the area, and temperatures drop into the 20s.  Therefore a few slick spots could develop, especially on bridges and overpasses, this is something we will continue to monitor as well.

If you are traveling north towards Nashville on Friday, there will be a better chance for wintry precipitation. The biggest impacts will be across northern and eastern Tennessee, with little to no accumulation expected for middle Tennessee, the Nashville area and only very light possible along the Cumberland Plateau.  Roads could be on the slick side, so use caution if you will be heading up that way!  Below is a graphic from the Hydrometeorological Prediction Center, showing the 24-Hour Probability of Snow Accumulation greater than, or equal to one inch, from Thursday evening to Friday evening, showing the best chance for any snow accumulation in extreme Northeast Alabama and the eastern half of Tennessee.

snow

- Jennifer Watson

Twitter: @JWatson_Wx

Facebook: Jennifer Watson WHNT