textproduct: Greenville-Spartanburg

SYNOPSIS

An arctic high pressure system builds over the area behind a passing cold front tonight, bringing bitterly cold temperatures into Monday. The high will then slide east of the area, allowing temperatures to quickly rebound by midweek. Rain chances return with an approaching cold front late in the week.

NEAR TERM /THROUGH MONDAY/

As of 650 PM EST Sunday: Gusty winds continue with windchill values between 15 to 25 degrees for most locations outside of the mountains, and single digits in the mountains, with below zero values in the higher elevations. There are signs of winds subsiding, but gusts should linger through the rest of the evening. Otherwise, the forecast remains on track with slight adjustments made based on current observations and latest model trends.

Arctic high pressure will allow a very dry and cold air mass to continue to build into the forecast area through tonight. Guidance indicates acceleration of NW winds at the top of the mixed layer this evening as inversion begins setting up over the lower elevations...with an increasingly strong mountain wave signal. Surface winds are therefore expected to increase for a window of a few hours this evening, especially on the leeward slopes of the Blue Ridge escarpment. Forecast gusts are sufficient to warrant issuance of a small Wind Advisory for Avery County as well as the high elevations of Burke County...where gusts of 45 to 50 mph appear likely. Winds will be weaker farther south along the escarpment (with the exception of the higher peaks), but gusts of 35 to 45 mph can be expected as far south as the Black Mountain area. Otherwise, the cold weather will be the main story, with a Cold Weather Advisory remaining in effect for mainly the high elevations of the NC mountains, as well as a small part of the NC Piedmont in the Charlotte area...where the forecast calls for wind chills to dip to around 10 above for an hour or two tonight. Forecast wind chill values otherwise remain too high to warrant an Advisory in other areas. Min temps will be almost 20 degrees below normal. The cold weather will continue into Monday, with forecast maxes around 15 degrees below climo, but with light/variable winds expected, wind chill values will quickly increase above Advisory criteria by late morning.

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/

As of 1220 PM EST Sunday:

Key Message: A quick warming trend Tuesday through Wednesday with dry conditions expected.

Quiet weather expected during the middle of the week, as a moderating arctic high slides east into the Atlantic under quasi-zonal flow aloft. Temps will start out chilly Tuesday morning, but rebound to near normal for aftn highs under sunny skies. Increasing clouds expected Tuesday night thru Wednesday as an upper shortwave ripples thru the region. Not enough moisture expected for any precipitation with this wave. Temps will bottom out near normal Tuesday night and warm to slightly above normal Wednesday.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

As of 1230 PM EST Sunday:

Key Message: Rain chances return Thursday into Thursday night with temperatures slightly above normal.

An upper trough will dig into the central CONUS Thursday and swing through the Appalachians Friday. Models are coming into better agreement on the amplitude and timing of the trough. This trend results in a little more moisture tap out of the Gulf with an associated cold front crossing the Southeast. PoPs ramp up to Thursday aftn in the mountains and across the entire area Thursday night, ranging from likely in the Piedmont to categorical in the mountains. QPF looks fairly light with the front being quick-moving. Temps should be warm enough to keep the bulk of the precip as just rain. But cold air will start to slip in early Friday morning just as precip tapers off, which may result in some changeover to snow in the highest elevations before drying out completely late morning. Little to no snow accums are expected. The air mass behind the front is relatively mild, with temps remaining near normal Friday and back above normal during the weekend. Models are not in very good agreement on whether rain chances return over the weekend. The latest NBM has 20-40% PoPs in the mountains Sunday, but some guidance suggests Sunday will remain dry.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Very gusty northwesterly winds will gradually subside by midnight tonight across all TAF sites besides KAVL, where lingering gusts are expected through a good portion of the overnight period. Direction will toggle slightly more northerly to northeasterly overnight, before becoming more variable by Monday morning, while KAVL maintains a northwesterly component. Light southwesterly winds are expected by the end of the period. Mostly clear skies expected with some wisp of cirrus possible for the NC terminals by Monday afternoon.

Outlook: Dry high pressure keeps VFR conditions in place through mid-week. The next cold front will bring shower chances and possibly restrictions Wed night/Thursday, with dry conditions returning for Friday.

GSP WATCHES/WARNINGS/ADVISORIES

GA...None. NC...Wind Advisory until midnight EST tonight for NCZ033-503. Cold Weather Advisory until 9 AM EST Monday for NCZ033-048>052- 058-059-070>072-082. SC...None.