143
FXUS62 KGSP 241740
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
140 PM EDT Mon Aug 24 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...
1. Dry weather with comfortable humidity levels will continue
through Tuesday. Then humidity increases along with daily shower
and thunderstorm chances returning Wednesday and continuing
through the rest of the week.

&&

.DISCUSSION...
Key message 1: Dry weather with comfortable humidity levels will
continue through Tuesday. Then humidity increases along with daily
shower and thunderstorm chances returning Wednesday and continuing
through the rest of the week.

The upper pattern still consists of a large anticyclone over
New Mexico and an upper low over the eastern Great Lakes. This
pattern effectively persists through Tuesday, even as the upper low
migrates eastward into Maritime Canada. Northerly low-level winds
will advect dry continental air into the region today, and even
though winds may favor southwest again Tuesday, they will be light
and incapable of significant moisture return. Vertical profiles
remain dry/subsident and unfavorable for deep convection, so PoPs
remain near zero through Tuesday night. Daytime temperatures should
run near normal. Afternoon mixing will maintain low dewpoints in
the lower 60s, with upper 50s across much of the mountains and in
the better-mixed Piedmont locations. Low temps tonight or Tuesday
morning will be a few degrees below normal again on account of the
lower dewpoints and good radiational cooling conditions. Slight
moisture return does begin Tuesday night, so Wednesday morning
temps will be closer to normal.

On Wednesday, just as heights trend upward behind the Maritimes
low, another well defined shortwave rotates over Lake Superior,
in turn strengthening cyclonic flow over the eastern CONUS. Winds
turn more decidedly S to SW over our region as the stalled front
south of our area is reactivated. Temperatures stay similar but
afternoon RH will be more typical for this time of year. The
moistening low levels make profiles again favorable for deep
convection, and scattered showers/storms return to the forecast Wed
afternoon; PoPs have increased to likely (~60%) over the mountains
on this cycle. The cyclonic flow overlying the sfc baroclinic zone
easily can result in continuing nocturnal shower/storm activity,
and warrants maintaining 30-50% PoPs for most of the area into
Thu morning. Some of the higher res models, including the NAM,
depict convection in the Ozarks or Mid-South on Wednesday forming an
MCV which could further enhance development. Even if that doesn`t
occur, relatively slow storm motion, potential for clustering, and
elevated PWATs suggest a localized flash flood threat. On Thursday
the main shortwave axis swings across the Ohio Valley carrying a
cold front into that area; broadly convergent flow remains over
the CWA and PWATs continue to increase across the Piedmont, with
lower 70s dewpoints again likely across the Piedmont. Though upper
forcing and convective parameters don`t clearly increase, model
QPF response is greatest that day and we end up with 60-80% PoPs.

The Great Lakes shortwave slides by to our north Thursday night,
possibly pulling the cold front across the Appalachians, though
with only subtle height rises thereafter, and the upper pattern
gradually dampening out, it`s hard to believe that effective
airmass change will occur. The more likely scenario would appear
to be the front stalling across the region, with drying
occurring only gradually Friday through the weekend as the upper
flow becomes more zonal, with a broad 500mb ridge taking shape
over the southern CONUS. Daily precip chances remain high chance
to likely, above climatological chances, on Friday, but trend
slowly lower Saturday and Sunday. Temperatures remain near
normal Friday- Saturday but with elevated dewpoints making for
muggy conditions, though heat index does not look likely to
exceed 100.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR under mostly SKC this afternoon, aside
from FEW cumulus at 050-070. Winds are light, generally NW across
NC but VRB or occasionally SW over Upstate SC, but all locations
should trend N to NE when not calm tonight. Mountain valley fog
is likely to develop late tonight though most likely won`t reach
KAVL. Flow above the PBL is expected to turn southerly Tuesday
and KAVL should flip to the SE during the morning after onset of
mixing. Elsewhere mixing is more likely to result in VRB if having
an impact at all, so no additional line to flip winds group appears
justifiable at this time.

Outlook: SHRA/TSRA could return to the terminals Wednesday
afternoon. A better chance of SHRA/TSRA is forecast Wednesday night
through Friday. Mountain valley fog and low stratus is possible
each morning. A chance of afternoon and evening SHRA/TSRA may
persist this weekend.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$

JCW