textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

PoP and QPF adjusted for latest guidance and current conditions.

KEY MESSAGES

1. Convection will continue to overspread the area from the west this evening, with a low end severe storm and flood threat. Dense fog possible overnight. 2. Unsettled weather continues for the foreseeable future, as the synoptic pattern remains stagnant and the Carolinas and northeast Georgia remain trapped within a moist air mass.

DISCUSSION

Key message 1: Convection will continue to overspread the area from the west this evening, with a low end severe storm and flood threat. Dense fog possible overnight.

Cold air damming continues to gradually erode across the area this evening, with the effective warm front currently extending from roughly the I-85 corridor in NC, southwest to the vicinity of the Lakelands in SC/GA. An area of showers with scattered embedded thunderstorms is currently along the western and southern CWA boundary, and this will continue to move NE through the evening. The convection is in a race against the nocturnal cooling cycle, but an area of 1000 J/kg of sbCAPE is currently analyzed just south of the boundary, so some potential for strong convection persists into late evening in this area. Also can't rule out a stray, marginally severe storm, especially with any rotating storms that cross the boundary from the warm sector. Locally heavy rainfall is also expected, with a small threat of flash flooding in locations of training/repeating cells...especially where unstable air overlaps with locations that have seen the heaviest rainfall in recent days (i.e., the SC Piedmont.)

The convection moves east of the area overnight as a short wave trough/MCV moves east. Low clouds and fog spread back across the area in the wake of the showers, with patchy dense fog again possible.

Key message 2: Unsettled weather continues for the foreseeable future, as the synoptic pattern remains stagnant and the Carolinas and northeast Georgia remain trapped within a moist air mass.

Monday looks to be similar to today with a lingering but weaker wedge, at least during the morning. A short wave crosses the area during the evening bringing another shot of loosely organized convection. Increased instability and weak shear will keep the threat of a few strong to severe storms. This also keeps a low end flood threat in place, with heavy rainfall possible over the western portions of the forecast area.

Mainly diurnal convection continues through the week with a moist and unstable air mass over the area, although there may be a slight downturn by Thursday. However, chances creep back up for the weekend as a cold front drops into the area and waves of low pressure move along the front. Temps slowly rise to a little above normal by Thursday, then drop back below normal for the weekend.

AVIATION /00Z MONDAY THROUGH FRIDAY/

At KCLT and elsewhere: An area of showers and thunderstorms is currently moving into the Terminal Forecast Area from the west, and should progress across at least the western half of the area through the evening. TS will be most likely at the upstate SC terminals, and tempos for TSRA along with categorical SHRA/VCTS are carried there. TS chances will be lower to the north and east, but scattered storms developing across the SC Piedmont this evening could make a run toward KCLT by mid-evening...and a Prob30 for TSRA is warranted at KCLT from 01-05Z.

Showers and storms will diminish and coverage and intensity and move east from late evening into the early part of the overnight. This will give way to a return of low cigs, with LIFR conditions expected to develop at most terminals after midnight. Reduced visby is also expected...primarily MVFR (with IFR possible in heavier rain showers and storms this evening.) Cigs and visby are forecast to begin improving during late morning, with MVFR forecast by afternoon. VFR could develop by late afternoon, but expected warmer/more unstable conditions are expected to result in more in the way of scattered diurnal convection developing Monday afternoon...warranting Prob30s for TSRA at all sites. Lingering, mostly light NE winds are expected to become light/variable at most sites overnight, with light SSW winds expected to develop Mon afternoon.

Outlook: The pattern will remain unsettled and murky for the foreseeable future, with at least scattered diurnal convection, possibly persisting into the overnight hours, and lowered visibility and ceilings forecast each night through at least the end of the work week.

GSP WATCHES/WARNINGS/ADVISORIES

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