textproduct: Greenville-Spartanburg

SYNOPSIS

Dry high pressure builds into the region tonight through Tuesday. Another cold front may bring precipitation chances back Wednesday night into Thursday, mainly in the mountains. Cold high pressure builds in behind that front Friday into next weekend.

NEAR TERM /THROUGH MONDAY/

As of 630 PM EST Sunday:

Key Message #1: Diminishing winds and cold conditions overnight.

Wind gusts are in the process of diminishing across the area as mixing is weakening and the pressure gradient is relaxing in response to the center of surface high pressure beginning to settle over the southern Appalachians. Otherwise, snow showers and much of the cloud cover across the mountains and northern zones has dissipated as the upper trough axis has pushed east of the area and moisture along the western slopes has become very shallow.

With good radiational cooling conditions eventually expected across much of the area, overnight lows are forecast to run 5-10 degrees below normal. Surface high will fully set up shop across the Southeast on Monday as a surface lee trough helps veer winds out of the southwest by Monday afternoon. With partly to mostly sunny skies expect afternoon highs on Monday to be near-normal.

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/

As of 1225 PM EST Sunday...

Key Message #1: Dry and quiet weather expected through the first half of the workweek.

Quiet weather will continue on Tuesday as high pressure lingers across the Southeast. An upper trough will dig across the Great Lakes and bring a cold front into the Ohio Valley. Dry conditions will continue, with dewpts likely mixing out lower than the NBM once again Tuesday aftn. Winds should remain fairly light out of the W/SW, but there could be elevated fire weather concerns in our far southeast zones, which didn't get much rain recently, as RH values approach 25%. Temps will warm to a few degrees above normal under sunny skies. As the front approaches from the NW Wednesday, moisture/cloud cover will increase atop the CWFA, while SW winds pick up and become breezy in the aftn. PoPs ramp up into the chance range along the TN border by the end of the day, but should start out as mainly rain showers, with temps still a few degrees above normal.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

As of 1245 PM EST Sunday...

Key Message #1: A northwest flow snow event may bring some minor accumulations across the mountains, mainly near the TN border Wednesday night through Thursday.

The latest guidance has come into better agreement on a dynamic/strongly-forced trough swinging through the OH/TN valleys and even closing off into an upper low as it reaches the Southern Appalachians by Thursday. This forcing will have enough moisture to work with, and may be enhanced by a zone of frontogenesis that pushes into the mountains from the west. Dry westerly to west-southwesterly flow east of the mountains will limit PoPs. But 850 mb temps fall Wednesday night in the mountains as moisture ramps up. So confidence is increasing on at least advisory-level snow accums along the TN border in the usual NW flow upslope areas. Most of the snow looks to fall Wednesday night thru Thursday morning. A sfc low will likely form in response to the upper low, somewhere invof the Central Appalachians or Mid-Atlantic Thursday. This may allow some wrap-around moisture to spill east of the mountains Thursday. But per usual, temps will start out a little too warm for snow east of the mountains, and it will be race between the moisture and cold air. But if moisture can linger long enough during the day, we could see some snow flakes outside the mountains in spots. Confidence remains low, and even if somehow the cold air and moisture overlap, snow accums should be spotty and light.

Key Message #2: Arctic air returns Thursday night into Friday, ushering in gusty winds and dangerous wind chills in the high elevations. Below-normal temperatures continue through next weekend.

Temps expected to plummet into the single digits and teens behind an arctic front Thursday night across the high terrain. Winds will be gusty, but expected to stay below advisory criteria, except for the highest peaks. But wind chills may dip into the -5 to -10 deg F range above 3500 ft in the northern mountains overnight thru daybreak Friday. Lows in the Piedmont will be in the upper teens to lower 20s.

Cold air will remain in place heading into the weekend, as a series of shortwaves reinforce a deep upper trough across the eastern CONUS. There remains a lot of disagreement among the guidance on a potential southern stream shortwave that could bring moisture into the region over the weekend. The system may be similar to the midweek storm, with mainly a NW flow snow event and some showers breaking containment east of the mountains as the system departs. But the 00Z ECMWF and 12Z Canadian have come in drier with the system. The latest NBM has slight chc to low-end chc ramping up mainly in the mountains late Saturday. Otherwise, it should be dry with temps remaining below normal.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: Dry and cold high pressure will progress across the region through this forecast period, resulting in continued VFR/generally SKC conditions through the period. Gusty NNW winds (gusts to around 25 kts) will continue this evening at KAVL, with NW winds of around 10 kts expected elsewhere. Winds will steadily diminish from late evening on, with light/variable winds expected by daybreak at most sites, with generally light NW winds expected by that time at KAVL. Winds are expected to become SW at 5-10 kts Monday afternoon.

Outlook: Expect dry VFR conditions for the first half of the week with surface high pressure over the region. Another frontal system will approach on Wednesday and may bring showers and associated restrictions. Some wintry precip could affect KAVL and perhaps KHKY early Thursday morning. Drier conditions return Friday.

GSP WATCHES/WARNINGS/ADVISORIES

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