textproduct: Greenville-Spartanburg

SYNOPSIS

Cold high pressure builds in through Saturday. A cold front arrives Sunday with a secondary low pressure system on Tuesday. This may result in lingering precipitation chances through the first half of the upcoming week. Dry high pressure returns on Wednesday.

NEAR TERM /THROUGH TONIGHT/

As of 1054 PM Wednesday: A quiet and cool Thanksgiving Day is in store across the region as the axis of a deep upper trough swings across the Appalachians. At the surface, a sprawling high will settle across the Great Plains and slowly nudge into the Southern Appalachians. A cold airmass has begun to advect into the area behind last night's cold frontal passage. Cold advection continues through the period with afternoon highs range from the low 40s to low 50s beneath mostly sunny skies apart of occasional bouts of high clouds streaming overhead. Wind gusts will gradually subside through the morning, but will remain elevated enough over the high terrain of the northern mountains to keep the wind advisory going as advertised. By tonight, temperatures will fall into the upper teens to upper 20s but conditions won't quite be textbook for radiational cooling as the pressure gradient remains tight enough across the area to keep some degree of mixing in the boundary layer.

SHORT TERM /FRIDAY THROUGH SATURDAY/

As of 1240 AM EST Thanksgiving Day: The center of dry and cold high pressure builds into the area through Friday night then slides off shore Saturday leaving a ridge over our area. Windy to breezy conditions continue Friday before the pressure gradient relaxes as the center of the high moves across the area. Highs will be 10 to 15 degrees below normal both days, with lows Friday night 10 to 15 degrees below normal as well.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

As of 110 AM EST Thanksgiving Day: A cold front approaches the area Saturday night, moves into the area Sunday and stalls near or just south of the area Sunday night into Monday. The GFS remains the slowest with moisture increase ahead of the front, and the new ECMWF has also trended that way. The Canadian remains the fastest, although it has trended drier. A drier solution seems more likely given the weak forcing and isentropic lift as the low level flow remains more west to southwest. There will be some cold air lingering across the mountains into the NC Blue Ridge area where if precip were to move in fast enough, precip would start at freezing rain before transitioning to all rain. Outside of these locations all rain is expected. That said, the LREF ensemble mean chance of a light ice accretion has increased to 30 to 40% where last nights run was 20% or less. Therefore, with the drying trend, expect only a very light and short period of spotty freezing rain late Sat nite and early Sun morn. Right now, it looks like any ice would be very light and mainly elevated surfaces. Rain spreads across the area Sunday then tapers off Sunday night into Monday as the front moves south of the area and another high pressure moves into New England setting up another cold air damming scenario. Temps Sunday around 10 degrees below normal. Lows Monday morning rise to around normal while highs remain around 10 degrees below normal.

A southern stream Gulf low spins up and moves south of the area Monday night and to the Atlantic coast Tuesday. The GFS and Canadian are faster moving the low to the NY coast by the end of the day. The ECMWF is slower moving the low to the Delmarva. The bigger story is the track of the low. The GFS and ECMWF are farther north which keeps a stronger CAD from setting up, meaning warmer surface temps and a rain forecast. The Canadian is farther south allowing a stronger CAD, colder surface temps, and the potential for a period of freezing rain from along and near the Blue Ridge to the I-40 corridor. The LREF ensemble mean shows a less than 20% chance of accumulating ice Monday night into Tuesday morning. Therefore, have kept any accumulating freezing rain out of the forecast for now. Of course, this will need to be monitored as the time frame approaches.

Precip tapers off late Tue into Tue nite as the low pulls away from the area. A period of NW flow snow is possible Tue nite into Wed morning with dry conditions elsewhere. Windy to breezy conditions are also possible as the low moves by. Lows near normal Monday night fall to around 5 degrees below normal Tuesday night. Highs around 10 degrees below normal Tuesday rise to around 5 degrees below normal Wednesday.

AVIATION /12Z THURSDAY THROUGH MONDAY/

At KCLT and elsewhere: VFR conditions will prevail through the TAF period at all terminals as dry high pressure gradually builds into the area following a cold frontal passage. Gusty winds will continue at KAVL and KHKY through most of the period. Otherwise, high clouds will stream across the region through the morning and into the afternoon before clear skies return this evening. Gusts will likely continue this evening into the overnight at KAVL, but should subside elsewhere.

Outlook: Dry and VFR through the rest of the week. A storm system approaches the area Sunday, bringing the next chance for flight restrictions.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...Wind Advisory until 11 AM EST this morning for NCZ033-049-050. SC...None.