textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

An increase in snow probabilities across much of the NC mountains and NC Piedmont tonight, but accums are expected to be light.

Confidence increasing on snow shower chances along the TN border Friday night. Confidence remains low on any amounts.

KEY MESSAGES

1. Periods of mainly light rain across the area today. There is a chance that rain could mix with or change over to snow showers across North Carolina tonight, with only spotty very light accumulations expected. 2. Scattered snow showers are expected along the TN border Friday afternoon and evening after a cold front moves through, which could result in some travel impacts Friday night. Very gusty winds also expected across the NC mountains. Otherwise, temperatures return to seasonal averages through the weekend and finally climb above normal early next week.

DISCUSSION

Key message 1: Periods of mainly light rain across the area today. There is a chance that rain could mix with or change over to snow showers across North Carolina tonight, with only spotty very light accumulations expected.

A positively tilted upper trough will sharpen and deepen over the Ohio Valley to the Lower MS Valley today. This energy will help strengthen a sfc low pressure center along a slow-moving cold front as it crosses the forecast area. A band of light rain (with possibly some snow and freezing rain on the highest peaks) will largely exit to our east this morning, resulting in a lull, before more rain develops as the sfc low pushes east across the area and provides low-level lift. Temps will remain below normal today under mostly cloudy skies, with highs mainly in the mid 40s in the NW NC Piedmont to mid 50s in the NE GA Piedmont.

Tonight, the low will begin to drift southeast across the Midlands, while the eastern edge of a cool, dry high pressure system will nose into the Mid-Atlantic and push a backdoor cold front thru the area. The low will organize such that a deformation zone may produce some light precip across the NC mountains and NC Piedmont this evening into the overnight. Temps will be falling into the 30s and thicknesses support a changeover to snow from NW to SE across our NC zones. QPF will be light, and a dry slot will lower the saturated layer such that there is uncertainty how much dendritic growth there will be in the precip shield. And temps don't really fall below freezing until the PoPs taper off to slight chc. So while patchy light snow accums look possible across portions of the NC mountains and NC Piedmont, accums look to be generally a dusting to a couple tenths of an inch (with locally higher amounts possible). If models trend toward more overlap between moisture and the cold air, accums may be bumped up and a Winter Weather Advisory may be needed in spots. Will let the day shift assess the latest guidance and make a decision on that. Either way, lows Thursday morning should be in the 20s to lower 30s everywhere, except staying just above freezing in the Upper Savannah Valley.

Key message 2: Scattered snow showers are expected along the TN border Friday afternoon and evening after a cold front moves through, which could result in some travel impacts Friday night. Very gusty winds also expected across the NC mountains. Otherwise, temperatures return to seasonal averages through the weekend and finally climb above normal early next week.

Model guidance continues to show a clipper low moving from the Great Lakes to New England Friday and off the coast Saturday. A trailing cold front crosses the area late Friday or Friday night. Moisture and northwest upslope flow develop producing precip across mainly the northern mountains. Thermal profiles show this would be snow. The models differ on the QPF and resultant snow accums; however, the potential for advisory level snow, at least across the higher elevations, has increased. Will keep an eye on this as the event approaches. Precip tapers off quickly Saturday morning. Very gusty winds develop behind the front as well. Gusts could increase into Wind Advisory criteria across portions of the NC mountains, especially the higher elevations. This will be monitored as well.

The remainder of the forecast was kept dry. Temps return to near normal through the weekend and above normal early next week.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

At KCLT and elsewhere: Pretty much all of the sct shower activity has been confined just to our south over the past few hrs. The lull in precip is expected to continue thru the morning, with coverage increasing again late morning into the afternoon, especially over our southern and eastern zones. At the same time, a backdoor front moves thru and toggles winds from SW to NE across the Piedmont. Confidence remains below average wrt the timing of this wind shift and how it will effect cigs. There could be some improvement as dry air works in from the NE, but this may be offset by any additional precipitation. Regardless, -RA is likely to linger over the fcst area into early Thursday. This will be complimented by IFR to LIFR cigs and mostly MVFR visby, with VFR conditions not expected to return until just beyond the 12z taf period.

Outlook: Restrictions remain possible thru early Thursday with a small chance of snow showers mixing in with rain across the NC Piedmont overnight. Little to no accumulations are expected. Otherwise, drier conditions return by Thurs afternoon and persist thru the weekend. Gusty winds develop Fri in association with a cold front and linger across the mtns thru Sat, but will gradually taper off east of the mtns by Fri evening.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...None. SC...None.