textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

Updated the aviation discussion for the 00Z TAF issuance.

KEY MESSAGES

1. Convection returns along a cold front through the early evening hours. Dry and Cooler on Friday. 2. Rain chances increase over the weekend and again on Monday as a cold front moves thru the area. Expect dry conditions in the wake of the front on Tuesday.

DISCUSSION

Key message 1: Convection returns along a cold front through the early evening hours. Dry and Cooler on Friday.

The cold front is currently sliding across the Piedmont zones of the CWFA. Ongoing convection along the front continues over the Charlotte Metro, mainly south of Charlotte down through the I-77 corridor as an outflow boundary pushes south. This will continue to initiate showers and thunderstorms over the next few hours before the atmosphere stabilizes and becomes overturned. The current environment doesn't support a severe threat, but heavy rainfall will accompany any heavier shower or thunderstorm. Most locations outside of the aforementioned area should remain dry this evening. Low end gusty winds are possible outside of the mountains with the front while windy conditions continue into the evening over the mountains.

Skies clear and winds diminish overnight as cool high pressure builds in behind the front. Lows will be 5 to 10 degrees below normal. Can't rule out some patchy frost in sheltered NC mountain valleys. Mostly sunny skies and light winds with the center of high pressure moving east across the area Friday. Highs 5 to 10 degrees below normal as well.

Key message 2: Rain chances increase over the weekend and again on Monday as a cold front moves thru the area. Expect dry conditions in the wake of the front on Tuesday.

Very broad upper trofing will persist well to our north thru the weekend and into early next week. By early next week, the trof will amplify southward with the trof axis moving overhead late Monday/ early Tuesday. At the sfc, high pressure will move off the Atlantic Coast by early Saturday with SLY return flow settling back over our area. A weak cold front is expected to move thru our CWA Saturday afternoon, but little in the way of airmass change is expected with it. Isolated to scattered showers are possible on Saturday, with the latest guidance increasing precip chances over our southern zones. Most of our NC zones only have a slight chance for precip, with any amounts generally less than 0.05 inches. The further you go south, the higher the precip chances, with our southern-most zones currently fcst to get roughly 0.25 inches thru the day. We could also see a few thunderstorms over our southern zones as well, but any severe threat appears minimal. On Sunday, a series of upper shortwaves translate across the Southeast, providing some amount of upper-level support for ascent. At the sfc, persistent SLY winds advect deeper moisture over the region ahead of a frontal bndy off to the west. The latest guidance still has a decent QPF response wrt pre-frontal showers starting as early as late Saturday night and continuing thru Sunday with the frontal passage early Monday. We can expect most of the precip late Saturday thru Sunday to fall over our SC and NE GA zones (up to about half an inch), with minimal amounts over western NC (ie, less than 0.1 inches). In addition, model profiles are more conducive for thunderstorms Sunday aftn/evening, with 500+ J/kg of sfc-based CAPE across much of our CWA. On Monday, sct showers are more likely across our entire fcst area, but precip amounts remain minimal and generally < 0.1 inches. In addition, we could see a few thunderstorms outside of the mtns Monday afternoon/evening.

Otherwise, drying high pressure spreads over the region late Monday into Tuesday, with another cold front moving thru our fcst area on Wednesday possibly producing some sct showers. Temperatures warm back to near-normal by Sunday, with cooler values behind the front for the first half of next week.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

At KCLT and elsewhere: The cold front is currently moving across the area with winds turning out of the north and northwest. Showers and thunderstorms have pushed south of KCLT, so took out any thunder mention, but placed a VCSH in the prevailing line through 01Z for the activity to the south of the terminal. Low-end gusts will gradually subside through the evening, with the exception of KAVL. Gusts should wane at KAVL overnight tonight as clouds clear once the front pushes across the area over the next few hours. Mostly clear skies for Friday, with the potential for some peak heating cu around 050 at the Upstate sites and KAVL. Winds are expected to shift out of the south to southwest by Friday afternoon.

Outlook: Cannot rule out restrictions Saturday with return of some moisture. Another cold front impacts the region late this weekend into Monday bringing another round of rain and associated restrictions. Dry and VFR Tuesday.

GSP WATCHES/WARNINGS/ADVISORIES

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