Plunging Temperatures Changing Rain to Ice and Snow in South: Winter Storm Thor Timing

Linda Lam
Published: March 4,2015




 

A wild weather ride is beginning in the South as Winter Storm Thor pulls freezing-cold air southward into a balmy air mass, bringing quickly changing weather conditions.
(MORE: Complete Winter Storm Thor Forecast)

Current Temperatures and Winter Weather Watches/Warnings

Warmer temperatures surged north ahead of Winter Storm Thor, bringing hope of spring across much of the South. But those temperatures are crashing an arctic cold front pushes southward.
(MORE: Warmer Temperatures to Start March)
In fact, many locations that are under winter storm warnings, watches or advisories have seen temperatures in the 60s, 70s and even lower 80s over the past 24 hours.
(MAPS: Actual highs and lows)
Plummeting temperatures will lead to rain changing to freezing rain and even snow as Winter Storm Thor unfolds across the South through Thursday.

Timing: Temperatures Plunge, Rain Turns to Ice and Snow

Winter Storm Thor Timing

Much of the South will see temperatures drop 30 to 45 degrees in a 24-hour period thanks to yet another arctic cold front. In some cases, the plunge has been much more dramatic; for instance, Greenville, Mississippi, saw its temperature plummet 21 degrees in just 11 minutes early Wednesday afternoon, falling from 74 to 53.
As the arctic cold front advances southeast colder temperatures will begin to wedge into the region and as the temperatures drop towards the freezing mark, precipitation will transition from rain to freezing rain, sleet and eventually with enough cold air snow.
Temperatures started in the 50s and 60s for many locations early Wednesday from central Texas into the Tennessee Valley. However, by Wednesday night temperatures will have plummeted into the 20s, well below freezing.
Locations from Dallas to Little Rock and Memphis have seen temperatures fall throughout the day on Wednesday. Rain will begin to transition to freezing rain and sleet Wednesday afternoon or evening, with snow developing late Wednesday night into Thursday morning. A winter storm warning has been posted for each city, where a few inches of snow may accumulate atop a thin glaze of ice.
Nashville will also see falling temperatures on Wednesday with freezing rain expected Wednesday night and the freezing rain will change to snow overnight. Snow accumulation forecasts can be found here.

Current Temperatures

Wednesday Night's Forecast

Farther north in Louisville, Kentucky, rain and sleet will change to snow late Wednesday afternoon. The snow will continue through Thursday morning. An accumulation of more than 6 inches looks likely in Louisville as well as much of the Ohio Valley.
(MAPS: 10-Day Forecast)
The rain may end as freezing rain as temperatures tumble below the freezing mark Wednesday night into Thursday morning from Huntsville, Alabama to Austin, Texas. The rapid fall in temperature may also cause any water on the roads from earlier rainfall to turn into ice, particularly on bridges and overpasses.
For those areas, precipitation is likely to end before the whole atmosphere is cold enough to force a changeover to snow.
The fast changing weather will cause road conditions to change rapidly for the worse in many areas. Check back with weather.com and The Weather Channel for the latest forecast.

After Thor: Temperatures Keep Dropping

Behind Winter Storm Thor record-breaking cold will blast into the South through Friday. Numerous daily record low temperatures will be threatened both Thursday, Friday and Saturday morning. A few cities that could see record lows include Little Rock, Dallas, Jackson, Mississippi and Memphis.
Some locations may even see their coldest temperatures ever recorded so late in the season, including Nashville and Louisville, Kentucky, where temperatures may drop into the single digits.
Places where heavy snow accumulates will be more prone to record-setting cold late this week because snow cover absorbs less energy from the sun during the day and radiates (loses) more energy to outer space at night.
(MORE: First Week of March Record Cold)
The cold temperatures after the snow will also mean less melting of any snow and ice that accumulates. Some locations may not see much melting until the weekend.
MORE: Winter Storm Thor Photos