textproduct: Greenville-Spartanburg

WHAT HAS CHANGED

PoP and QPF adjusted for latest guidance and current conditions.

KEY MESSAGES

1. Convection returns by 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 returns by evening with a low end severe storm and flood threat. Dense fog possible overnight.

Cold air damming remains in place across the area this afternoon. There appears to be some thinning of the low clouds around the edges of the wedge. This could allow the moderate sbCAPE outside of the boundary to filter into locations along and south of I-85 and into the TN border counties. There is around 20 kts of low level shear over the area. Locations that see increased instability could see some strong to possibly severe storm storms late this afternoon into the evening when convective coverage increases ahead of a short wave crossing the area. There is weak muCAPE even in the heart of the wedge, so thunder could be heard anywhere convection moves through.

A low end flood threat remains as well, especially over the Upper Savannah River Valley and southwestern NC mountains where convective coverage will be higher and upslope flow may increase QPF response. Flooding would be more likely where training cells develop or increased rainfall rates linger.

The convection moves east of the area overnight as the short wave moves east. Low clouds and fog spread back across the area in the wake of the showers. Dense fog will again be 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 /18Z SUNDAY THROUGH FRIDAY/

At KCLT and elsewhere: Generally IFR to MVFR cigs will continue through the afternoon with any brief vsby restrictions related to showers moving north across the area. Expect convection to develop and move east across the area from late afternoon into the evening. These will come with IFR to MVFR cigs and MVFR, possibly brief IFR, vsby. After the showers move east, expect cigs to fall back to LIFR with IFR and possibly LIFR vsby, along with spotty shower chances. Should be a relatively quick return to VFR vsby by mid morning, but cigs will only slowly increase through IFR to MVFR by afternoon. NE winds, S at KAVL, continue into the evening becoming light and variable overnight. Winds pick up from the SW, NW at KAVL, through the day on Monday. Convection should hold off until later in the afternoon Monday.

Outlook: The pattern will remain unsettled and murky for the foreseeable future, with widespread diurnal convection, possibly persisting into the overnight hours, and lowered visibility and ceilings each night.

GSP WATCHES/WARNINGS/ADVISORIES

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