897
FXUS62 KGSP 200611
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
211 AM EDT Wed Aug 20 2025

.SYNOPSIS...
Showers and thunderstorms are expected only over the mountains and
foothills this afternoon and evening, but chances return to all
areas Thursday, and increase heading into the weekend. Temperatures
start out near normal then fall below normal for the weekend. Cooler
and drier conditions develop early next week after a cold front
crosses our region.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1:45 AM EDT Wednesday: Over the past couple of hrs, the last
of the lingering isolated showers appears to have finally dissipated
over our CWA. Another low deck of stratus is expected to spread over
at least a portion of our CWA thru the morning, but it remains unclear
how far south/west the clouds will spread. We can also expect patchy
fog overnight and into the morning, especially over the mtn valleys,
where it will likely be dense. Low temperatures will be mild again
this morning with values remaining a few degrees above climatology.

Otherwise, stout upper ridging will remain centered to our west thru
the near-term period. Long wave upper trofing over SE Canada will dig
southward over New England today, allowing for minimal height falls
across our area. At the sfc, broad high pressure will slowly move off
the New England Coast today as the wedge-like pattern continues to
dissipate over the western Carolinas. At the same time, Hurricane Erin
will approach the Carolina Coast later tonight and then being to track
NE by the end of the near-term period early Thursday. Overall, we can
expect another active day across the mtns with sct to numerous showers
and thunderstorms later this aftn and evening. It remains unclear how
far south and/or east any convection will develop today/tonight, but
the further you go south and/or east, the lower the PoPs. Like the past
few days, the severe potential looks minimal at best across our area
however an isolated flooding threat will exist especially over the mtns.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 1220 AM Wed: A narrow band of vorticity and weak cold front
will settle into the CWA Thursday, extending from the shortwave
moving off the East Coast as it picks up the circulation around Erin
and leads to the storm moving back out to sea. N to NE winds in low
levels will be associated with moisture advection and some pooling
along the front look to occur. Profiles will be weakly unstable and
near-climo PoPs will be advertised: 20-30% in the I-85 corridor and
40-60% over the mountains. Chances have trended slightly lower, and
skies slightly clearer in the model blend, so temps are now fcst to
remain slightly above normal. Slightly rising heights and sfc
ridging in the wake of those features will promote a turn to more
easterly winds Thu night which could kick off elevated convection,
so most areas east of the Blue Ridge Escarpment still feature chance
PoPs thru the night. Slight drying may occur in our north so the
best overall chances appear in the Escarpment areas south of US 74
and over the western Upstate. Locally heavy rain will remain a
concern with any convection given westerly upper level flow but only
weak or slightly easterly flow thru the midlevels, suggesting slow
storm motion and/or some anchoring along E or SE facing terrain.

On Friday several guidance members depict the sfc high setting up
east of the Appalachians. The boundary by then should be effectively
south of the CWA, and the progression of the high suggests a more
typical quasi-stationary frontal regime with some degree of southerly
upglide. 500mb trough overhead will help keep unstable profiles
across the CWA, but most favored over the mountains/Escarpment.
Widespread cloud cover should persist thru the day, which looks to
knock temps back several degrees. Maxes end up 3 to 6 below normal
over the Piedmont but still near normal in the valleys west of the
Escarpment. The upglide or upslope flow will continue weakly Friday
night but by then the trough axis should be in a less favorable
position to enhance convection, so PoPs decline slowly, best chances
being in the southern half of the CWA.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 100 AM Wed: Not much change to the thinking for Saturday; only
subtle changes to the pattern are expected. Flow will turn slightly
more southerly over the stalled front and the moist layer on prog
soundings is shown to deepen, with instability still tempered by
nearly moist-adiabatic lapse rates. Precip chances increase 5-10%
compared to Friday with similar, still below-normal temperatures.
Excessive rainfall will remain a concern with convection likely to be
slow-moving and possibly anchoring, though the likelihood of flooding
may be mitigated by the highest PWATs being south of the mountains,
nearer the front.

Heights fall over our region by early Sunday as vort lobe rounds the
upper low centered over Ontario; the surrounding trough phases with
what`s left of the baggy SE CONUS trough. GFS, for one, spins up a
compact coastal low as the trough phases, but tracking such that
minimal impact on sensible weather is expected for our Piedmont. Less
of a mountain-Piedmont gradient in PoPs is forecast with the incoming
trough veering winds to westerly in the mountains by peak heating,
but suggesting lee trough helping to spawn convection in the
Piedmont. Northwest flow and substantial mid to upper level drying
develops by Monday so most areas currently receive a dry fcst that
day. Min temps may trend slightly cooler Monday morning over the
mountains, but maxes east of the mountains will trend slightly warmer
again. Cool post-frontal air will settle over the area Monday night
with mins and maxes Tuesday a few degrees below normal, but with
dewpoints drying into the 50s that day as well; dry fcst once again.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: We`ve still got some lingering low stratus
over the northern NC mtns and foothills, but the rest of our fcst
area is predominately VFR. Another batch of low stratus is expected
to spread into our area overnight with MVFR to IFR ceilings across
a portion of our fcst area. A few instances of LIFR ceilings cannot
be completely ruled out either. Patchy fog will also be possible at
any terminal with the greatest likelihood at KAVL where dense fog
could materialize and also at KHKY. The morning stratus is expected
to be slow to sct and lift with at least MVFR ceilings fcst to linger
thru much of the morning with an eventual return to VFR by the aftn.
Expect another round of afternoon/evening convection over the mtns,
with a TEMPO for TSRA carried at KAVL and a PROB30 for TSRA at KHKY.
Coverage elsewhere is more uncertain, but a chance of late aftn/early
evening storms cannot be discounted at the other taf sites. Winds will
be light thru the period and mainly out of the NE, but also VRB at
times.

Outlook: Sct to numerous afternoon/evening showers and thunderstorms
and their associated restrictions are expected across the fcst area
Thursday and Friday. Morning fog and low stratus will also be possible
each day, especially in the mtn valleys.

&&

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

&&

$$

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