Not much has changed with the forecast for our rain and slushy snow event coming Sunday. I have a few concerns, though.
Here's the setup:
- A cold front is moving through South Carolina this afternoon, with fresh cold air filtering in behind it tonight through Sunday. However, the air mass moving in isn't extremely cold and doesn't have much momentum to push in before precipitation arrives.
- A storm system currently over the southern Plains will track near the Gulf Coast tonight and then northeastward near the Carolina coast Sunday, a favored winter storm track.
Rain will begin late tonight with snow mixing in by daybreak in the Upstate. As the storm gains strength upon arriving in our coastal areas Sunday morning, it will pull in colder air, turning the rain to snow steadily from west to east.
The computer models are in two different camps today with the potential for accumulations, but the situation is a little different than before.
Most models call for just light to moderate snow for 3-4 hours, not really coming down hard enough to overcome warm ground (it's 63° and mostly sunny in Columbia as I'm writing) and near-surface air temperatures above freezing. Most of the Upstate will see light precipitation overall; it's a light rain-to-flurries situation there. Along the coast, it's going to be mainly rain with a brief period of light snow at the end, with no accumulations except maybe for a bit of slush on car tops and decks. For areas in between, the snow comes down hard enough after the changeover that the ground may get whitened for a time. It's unlikely we'd see an accumulation on roads in this scenario.
Ensemble mean snowfall from the ECMWF ensemble model.
"Lame!" cry the snow lovers.
Image Source: WeatherBELL
The other camp looks similar, but with a period of heavier precipitation, and the changeover happens while it's coming down hard, pasting an area from roughly Aiken to Lancaster with 2-3 inches of wet snow at midday and early afternoon, before tapering to flurries. Warm ground and air temperatures a little above freezing would melt away an inch or so of that, but you'd still be left with an inch or so on the ground in this area. Only a couple of models show this idea, but this is the kind of surprise that winter storms have dealt us in the past.
Ensemble mean snowfall from the U. S. Short Range Ensemble Forecast shows the minority view of a band of more substantial snow from the CSRA to the Catawba River.
Snow lovers cry, "Bring it!!!" but the chances of this idea working out are under 20%.
Image Source: WeatherBELL
Precipitation ends from west to east through the afternoon, though sprinkles and flurries may hang on past nightfall in the Pee Dee. That's a problem because temperatures will drop to or below freezing by 8-9 p.m. over much of the state. Any lingering water or slush on the roads will freeze, creating icy patches that could persist into Monday morning as most of the state sees temperatures drop to the 20s. You'll have to be careful and watch for black ice if you're out Sunday night or early Monday. That will be especially true for any areas that see an accumulation from a period of heavier snow.
Sunshine and highs near 50° across the state on Monday for the King holiday would quickly eliminate any snow cover or icy patches; any slick spots should be gone by 10 a.m. We remain dry Monday through Wednesday behind the storm, followed by a chance for light rain Thursday and a better chance for rain next weekend.
Hang in there, snow lovers. Winter's not over after this event. It's looking like a cold weather pattern with winter storm chances will set up at the end of the month and last through the first week or so of February.