Smyrna, South Carolina Weather Forecast Discussion

888
FXUS62 KGSP 061041
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
641 AM EDT Sat Sep 6 2025
.SYNOPSIS...
Heat and humidity ahead of an approaching cold front will result
in development of scattered to numerous showers and storms across
the area this afternoon. A few strong to perhaps severe storms are
possible. Cooler and drier weather returns on Sunday and lingers
through at least the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 638 AM EDT Saturday: No major changes to the forecast this
morning.  Some of the convection over the Tennessee Valley made
it into the Smokies over the last 1-2 hours, but has mostly fallen
apart without much fanfare.  Radiation fog developed as anticipated
over parts of the NC Foothills, but has thus far remaind patchy
and isolated owing to a bank of thick cirrus streaming into the
area from more potent convection upstream.  Lows remain on track
to bottom out in the upper 60s across the low terrain.
Saturday will feature the arrival of the cold front at long
last, as the upper pattern amplifies once again and carries
the front eastward.  Operational guidance depicts an axis of
prefrontal convergence diving across the forecast area from late
morning into mid afternoon, exiting the eastern zones by evening.
Some 1500-2500 J/kg sbCAPE will be able to develop out ahead of
the front, which paired with some 25-30kts of deep shear should
result in good coverage of convection.  Shear vectors themselves
will, following the 500mb flow, be nearly parallel to the advancing
front, and so propagation out ahead of the boundary looks limited;
indeed, hi-res guidance keeps the advancing line more or less
aligned with the convergence axis all afternoon.  Also of note is
a subtle but undeniable dry slot, most pronounced over the I-77
corridor, which should boost dCAPE to values of 800-1000 J/kg.
All that to say, the eastern 2/3 of the forecast area could be
subject to a damaging wind threat with any storms that develop.
Convection will push east of the forecast area Saturday evening as
the front crosses through, and by Saturday night, drier dewpoints
should be building in.  Limited clearing will be in order for
the overnight as the upper-level front appears less pronounced
than at the surface.  Low temperatures will drop into the low-
to mid-60s all across the region...or even the 50s in the mountains.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 120 am EDT Saturday: An anomalous long wave trough will make a
brief reappearance early in the new week, before the core of the
polar jet retreats to the northeast Conus/southeast Canada, with
quasi-zonal flow, or perhaps a very broad, low amplitude trough left
behind across much of the East by the end of the period. At the
start of the short term...the leading edge of a frontal boundary is
expected to be well southeast of our forecast area, with cooler/
drier air gradually filtering in from the north. Nevertheless, just
enough moisture/perhaps weak instability is expected to linger to
support isolated showers and perhaps a TS through the daylight hours
Sunday. Sufficient dry/ stable conditions should be in place by
Sunday evening in order to preclude any precip chances through the
remainder of the period. Temps are forecast to be around 5 degrees
below normal Sun/Sun night, and almost 10 degrees below climo
Mon/Mon night.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 130 am EDT Saturday: The upper air pattern over the Conus
will steadily amplify through the extended, with a baggy trough
forecast over the Southeast for much of the period. Farther north,
New England and southeast Canada will sit under the southern
periphery of an upper low for much of the week, with confluent flow
supporting a persistent low level anticyclone and associated
inverted ridge extending southward to the east of the Appalachians.
Resultant E/NE flow will result in relatively cool and dry
conditions continuing across our CWA through the period, with below
normal temperatures...albeit with a gradual warming trend forecast
through the week (from 5-10 degrees below climo Tuesday to 2-3
degrees below by Friday). Still can`t rule out some moisture return
during mid-week in association with weak surface development near
the Carolina Coast (as consistently portrayed by the GFS). However,
the consensus of global deterministic and ensemble guidance leans
toward maintaining a dry forecast for now.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: As expected, fog has developed across parts
of the NC foothills, but has remained mostly patchy and isolated
based on available METAR observations.  Periods of VLIFR fog at
KHKY will continue until daybreak, when a quick return to VFR
is expected.  A line of semi-organized showers and thunderstorms
will cross the area ahead of an advancing cold front during the
day Saturday, warranting mention of TSRA - currently handled using
PROB30s - at all TAF sites.  Winds will stay SW ahead of the front,
but will turn NW behind the front.  Guidance has started hinting
at MVFR to IFR ceilings early Sunday morning, toward the end of
the period; have started hinting at such restrictions for tonight.
Outlook: Some showers and associated restrictions may linger behind
a cold front on Sunday; otherwise dry high pressure is expected
into early next week.  Fog and/or low stratus is possible each
morning, especially in the favored mountain valleys.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JDL
NEAR TERM...MPR
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...MPR

NWS GSP Office Area Forecast Discussion