.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... As of 300 PM Friday...Winter Storm Watches will be upgraded to Warnings with this afternoon forecast package, as confidence continues to increase in a significant winter event this weekend. A strong low pressure system will track from the Lower MS Valley thru the Deep South Saturday night, then across the Carolinas Sunday, lifting NE of the area Sunday night.
Models are in good agreement on the track and overall evolution of the cyclone. Strong forcing and ample moisture will provide a period of solid precip band crossing the area late Saturday night thru at mid-aftn Sunday, then a dry slot will punch in from the south and a deformation zone will pivot over the area Sunday evening. There will be nice supply of cold air, as a 1030-1035 mb sfc high will move across the Great Lakes to New England, causing strong hybrid cold air damming. So the forecast is on track for the mountains to get mostly snow with this entire event. Where it remains murky (as usual) is across most of the Piedmont, especially along I-85 and to the south.
The 12z models have trended stronger with a warm nose punching in with the warm conveyor belt, transitioning snow to sleet and freezing rain. In fact, it starts out warm enough that our southern zones from Elbert to Chester counties go straight from rain to freezing rain.
The latest trends result an uptick in ice accums across the entire Piedmont, and less snow/sleet. Either way, confidence is high enough on snow, sleet and/or ice impacts to upgrade the entire watch to a warning.
Damaging accumulations of ice continue to appear more likely along and south of a line from Anderson to Spartanburg to Gastonia, to Salisbury, including Charlotte and vicinity. Northwest of there, morning snow/sleet followed by a likely transition to freezing rain/drizzle of a few hours is expected to result in a somewhat narrow zone of a mixed bag of accums of 2 to 5 inches. Gusty NE winds within the CAD will add to the threat of power outages as ice accums on sides of wires, branches and poles. The forecast for the mountains and NC foothills continues to look on track, where 8-12 inches/locally higher amounts of mostly snow continue to look like the best bet. Strong cold advection combined with snow pack in some locations will result in min temps Sun night 10-15 degrees below normal...or well below freezing in most areas, so little improvement in road conditions can be expected through Monday morning. A brief, moist northwest flow in the wake of the departing cyclone could result in additional light accums across mainly the high elevations of the TN border counties Sun night.