Ware Shoals, South Carolina Weather Forecast Discussion

280
FXUS62 KGSP 211031
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
631 AM EDT Sun Sep 21 2025
.SYNOPSIS...
Scattered showers and thunderstorms are possible mainly in the
mountains today through Tuesday. Temperatures will remain at or
slightly above normal for this time of year. Unsettled weather
and cooler temperatures develop in the second half of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 130 AM EDT Sunday: A much quieter near term than the past few
days. The weak ridge slides offshore as heights rise slightly ahead
of a developing trough over the central CONUS. At the surface, an
area of high pressure remains steadfast over the NE and extends into
the CWA through the period. This very weak back door cold front
doesn`t bring much of a change in temps, but does drop the daily
high a degree or two. Meanwhile, a concentrated area of southerly
flow just east of the mountains on Sunday afternoon could result in
a stray shower over the far western NC zones. Confidence is low as
the more NE flow and drier air is likely to hinder shower
development, but cannot rule it out completely. So, will keep a
slight chance (15-30%) for this afternoon. Not expecting any other
activity Sunday night, just quiet and dry. Again, temps for today
reach the low to mid 80s as that cooler and drier NE air moves in.
&&
.SHORT TERM /MONDAY THROUGH TUESDAY/...
As of 1215 AM Sun, key message:
* Only subtle changes to the ongoing weather pattern through
  Tuesday. Isolated or widely scattered diurnal showers/storms Mon
  and Tue afternoons, mainly over the mountains, with
  temperatures remaining a few degrees above normal.
Bermuda ridge will remain off the East Coast thru Tuesday. Upper
troughing will be present from the Great Lakes to the Gulf Coast
Monday. As noted on previous cycles, the trough is of the baggy
variety, and the vort energy within looks mainly to result from
convection in the lower MS and OH Valleys, much of which is progged
to develop along a weak frontal zone or warm conveyor belt of the
weakening cyclone east of the Great Lakes. It looks unlikely that
front will have enough oomph to push east of the Appalachians until
Tuesday night at the earliest. Light SW flow and modest diurnal
instability make plausible a few showers/storms over the mountains,
mainly in the afternoon.  Activity could initiate west of the
mountains also, and track into our mountain zones. It is worth noting
the 21/00z NAM takes an embedded shortwave, arguably an MCV, and
develops it into a full-on compact low on Tuesday. While that feature
is depicted as tracking near the Ohio River, the model produces
spotty precip along or ahead of its cold front near the TN/NC border.
Such chances wrap into the low PoPs already forecast there; the NAM
appears an outlier anyway, and tends to develop lows like that that
never materialize. At any rate, not entirely out of the question.
Max temps Monday will be just slightly warmer than Sunday`s. Despite
the approach of the trough, heights aloft remain on a nearly neutral
if not slightly upward trend, but airmass modification continues, so
temps trend a few degrees higher Tuesday, ending up 5-7 above normal.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 1240 AM Sun: General expectation for the midweek period remains
that broad-scale troughing developing in the Mississippi Valley,
along with upper low moving from the Great Lakes to the Northeast,
should finally push the frontal zone across the southern
Appalachians. The front and associated clouds/precip arrive in our
area via an embedded shortwave moving across KY/TN, likely by late
Wednesday, although a few ensemble members depict that occurring as
soon as Tuesday night. Initially any boost to forcing looks subtle,
mainly attributed to low-level convergence and an increase in PWAT.
By Thursday models agree on a 500mb cutoff low having developed in
the mid-Mississippi Valley, but there remains spread as to how far
south it does so. Regardless, DPVA is likely to develop over our
region Thursday as heights fall.  Low-level frontogenesis and PWAT
then also ramp up, with precip chances and rates peaking Thu or Thu
night, mostly in the 60-75% (likely) range. The cold front associated
with the low looks to pass Friday, when likely PoPs also are
forecast.  Chances should diminish behind that feature, but as usual
with a cutoff low, there is wide spread in the speed and specific
location of the front and we may also be dealing with cold-core
showers or wraparound precip. Accordingly lower chances linger
Saturday. Temperatures trend a few degrees cooler Thu, back to around
normal in the mountains but still above in the Piedmont; maxes top
out around or a little below normal Fri-Sat.
Judging from SBCAPE plots from the major global models, and gradients
in LREF 25th-75th percentile theta-e at 925mb and 850mb, it looks
like we probably will be in the warm sector of the approaching low.
Shear vectors will be unidirectional and southwesterly, likely
exceeding 30 kt invof the front. CAPE is relatively muted, but
organized storms are not out of the question and could pose either a
damaging wind or heavy rain threat if these parameters verify.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions prevail across most terminals
through the TAF period. High pressure settles into the region and
keeps almost all restrictions at bay. KAVL continues with the usual
mountain FG/BR this morning, but should clear up after 14z. Winds
generally start out calm before picking back up out of the NE,
except at KAVL which stays more S. Winds remain light as well with
no concerns at this time. Tonight, there could be some MVFR at KCLT
closer to sunrise. Additionally, another TEMPO for these IFR/LIFR
restrictions is in place for 10z-14z for BR/FG.
Outlook: Dry weather returns to start the week. Rain chances may
return Tuesday thru midweek. Fog and stratus possible each morning
in the mountain valleys.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...Wimberley
NEAR TERM...CP
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...CP

NWS GSP Office Area Forecast Discussion