A low is moving in from the southwest, which will cause several different precip types in the mountains, and mostly rain for the Upstate. I'll start with the Upstate, which is rather cut and dry... well maybe not so DRY!
Upstate: Showers will push in tonight. We could see some sleet mixes with rain at the onset, but all rain should prevail for most of the night. NO road issues expected and temps at the surface will stay above freezing. Timeframe for the cold rain will be from around 11pm tonight to late morning Saturday. We'll get between 0.25" and 0.5" of rain for the Upstate most likely. It dries out by the afternoon and it will become breezy.
Mountains: It gets a bit more complicated for the mountains. We should start with sleet and freezing rain late this evening, since we'll have cold temps at the surface, but some melting going on in the upper levels. It should turn to mostly rain as the low gets closer overnight. Then as the low exits, snow will take over from northwest flow. So, I'm going with a wintry mix this evening/early overnight, rain late night, then snow near the TN border after noon on Saturday. Roads could become hazardous, especially in mountain valleys tonight where freezing rain could be prolonged a bit. 2-4 inches of snow will be possible Saturday night, which will cause hazardous driving conditions for those in counties bordering TN and elevations above 3,500 feet.
Another chance for rain and mixed precip comes on New Year's Day! But, we should get a nice break for Sunday and Monday.