364
FXUS62 KGSP 161039
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
639 AM EDT Sat Aug 16 2025

.SYNOPSIS...
Scattered showers and storms return today in the mountains and
parts of South Carolina and NE Georgia. Rain chances Sunday through
Tuesday will be mainly confined to the mountains. Temperatures
will trend upward through Monday but then trend cooler, ending up
below normal late in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM Sat: Patchy dense fog in parts of the Savannah Valley
and Lakelands where soils are wet following widespread rainfall
yesterday evening; fog layer appears to be very thin so we expect
improvement probably by 9 AM. Mountain valleys are filled mainly
with low stratus which should break up by 10-11 AM.

Water vapor imagery depicts a positively tilted trough axis nearing
the southern Appalachian spine. This axis will slowly drift toward
the SE coast thru tonight, while ridge strengthens in the lower MS
Valley. A moisture gradient will accordingly shift across the CWA
today, such that northwestern sections will see PWAT fall to 1.5
inches or less this aftn, but values remain near 2 inches thru peak
heating in our lower Piedmont. The dry air will limit convective
intensity/coverage over the mountains, but initiation still appears
possible from the ridgetops. CAMs depict spotty showers/storms
there and also in GA/SC where the moisture is better. Steering
flow will remain weak, largely out of the NE in low to midlevels
but westerly above 500 mb. Storm motion will remain slow and a
threat of locally heavy rain returns for another day, particularly
in GA/SC. If a tall storm is able to develop over the mountains,
it may be capable of near-severe gusts owing to large DCAPE and
sfc-midlevel delta-theta-e values within the drier air--but such
occurrence would appear highly isolated. Max temps again will be
a couple degrees above normal.

Convection is expected to diminish diurnally and skies look to
trend mostly clear tonight. Slightly drier air should allow temps
to drop a degree or two cooler for mins Sunday morning compared to
this morning, but RH will remain high. Mountain and river valley
fog remains possible.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 1:45 AM EDT Saturday: The short-term fcst picks up at 12z on
Sunday with broad upper ridging centered to our west and covering
most of the CONUS. We will remain under the eastern periphery of
the ridge thru the period. At the sfc, another round of robust
Canadian high pressure will slide SE and towards New England on
Sunday and provide some amount of drying from the north and in-
creasingly warm and suppressed profiles across our fcst area. On
Monday, the high continues to slide further east with its impacts
on our synoptic pattern lessening as the day wears on and we move
into Tuesday. Overall, the high`s influence should result in notably
less convective coverage thru the period with below climo PoPs across
our CWA on Sunday and below climo PoPs outside the mtns (near climo
over the mtns) for Monday. Model profiles continue to indicate that
any severe convection appears unlikely either day. High temps are
expected to be a few degrees above normal both days with Heat Index
values approaching 100 degrees over portions of the Upstate and Pied-
mont on Sunday afternoon. Values may briefly exceed 100 on Monday
afternoon, especially over the western SC Upstate.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 1:35 AM EDT Saturday: The extended fcst picks up at 12z on
Tuesday with broad upper ridging still covering most of the CONUS.
During the first 24 hours or so of the period, very broad upper
trofing will amplify over eastern Canada and briefly suppress the
ridge over the eastern CONUS. By late week, most of the long-range
guidance has the upper trof lifting NE with heights recovering mar-
ginally over the Southeast. At the sfc, high pressure will be cen-
tered well to our north over eastern Canada while Hurricane Erin
will be approaching the SE Coast. Over the next couple of days,
Erin will turn north and then NE and begin to move further off
the Atlantic Coast. At the same time, another round of weak high
pressure approaches our area from the NW, but appears to stall
as weak, SLY low-level flow from the Gulf persists thru the end
of the work week. This setup is expected to produce a broad area
of moist, low-level convergence across the Southeast for Thursday
and Friday. Overall, still expect a steady increase in diurnal PoPs
each day thru the end of the week. The severe potential still appears
minimal at best thru the period. Nonetheless, with a moist airmass
expected to persist over the region thru much of the period, the
potential for localized flooding will likely be the main concern.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Mountain valley fog/stratus just barely
outside KAVL at issuance time but think they most likely will remain
VFR, similar to Fri AM. The valley deck should scatter 13-14z. Areas
of LIFR/VLIFR fog in the Savannah River Valley extend to KAND and
TEMPO appears warranted for the first hr of the period. Cumulus
will break out 14-17z at MVFR to low VFR level. SCT SHRA/TSRA
in the mountains and in the lower GA/SC Piedmont. PROB30 at KAVL
for TS, and a short period of VCSH at the SC sites. Light N to NE
wind when not VRB this morning. Winds should trend toward NE with
mixing this morning; at KCLT winds eventually veer to ESE late in
the day, before backing again tonight. KAVL looks to flip to SE
around midday and remain there thru sunset. Patchy fog possible
again tonight where rain falls this aftn/evening, and mountain
valleys develop stratus again.

Outlook: Afternoon showers and thunderstorms with associated
restrictions are expected mainly across the mtns Sun-Tue.
Morning fog and low stratus are also possible, especially across
the mountain valleys.

&&

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

&&

$$

SYNOPSIS...Wimberley
NEAR TERM...Wimberley
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...Wimberley