644
FXUS62 KGSP 070620
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
220 AM EDT Tue Oct 7 2025

.SYNOPSIS...
High pressure lingers over the area today keeping low rain chances
and above normal temperatures around. Above normal temperatures
linger on Wednesday despite a cold front bringing isolated to
scattered showers and thunderstorms to the area. Drier and cooler
conditions return behind the front the rest of the week, with below
normal temperatures returning Thursday into Friday before a warming
trend develops this weekend into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 148 AM EDT Tuesday: Low cloud cover continues to remains
locked in over the area in the presence of a lingering in-situ
wedge as a surface high continues to drift further offshore over
the western Atlantic in response to a departing upper ridge. Steady
moist upglide is present, which is helping to keep the residual
wedge in place despite gradually losing its synoptic support
as the surface high moves further out the sea. All of this is
in response to a digging upper trough that will propagate from
central Canada and the Northern Great Plains to Atlantic Canada
and the northeastern CONUS by the end of the forecast period. An
associated cold front will shift towards the region through the
forecast period and be in the midst of shifting across the NC/TN
border by daybreak Wednesday. The low clouds early this morning
should stick around through the mid- to late morning hours before
better daytime mixing gets going as better low-level WAA filters
in and allows for the cloud deck to scatter. Current nighttime
Microphysics imagery shows areas along and south/east of I-85 that
have cleared for the time being. With dewpoints in the mid to upper
60s and light winds, enough radiational processes may develop patchy
dense fog just before daybreak as dewpoint depressions tighten. Will
have to monitor how this evolves throughout the overnight tonight
and if there will be a need for a Dense Fog Advisory. With the
presence of an extensive low cloud deck and elevated dewpoints,
morning lows will run 4-8 degrees above normal.

Model guidance are in agreement with the low-level (including at
the surface) flow turning south-southeasterly by the afternoon
hours as the lingering wedge seems to lose its battle with daytime
mixing and low-level WAA. Isentropic lift is still present during
peak heating as well, which model guidance have picked up on the
development of WAA driven showers across portions of the Piedmont
areas. In this case, placed a slight chance PoP during the afternoon
hours, but coverage will be isolated. May take some time for the
low clouds this morning to scatter out, but once insolation reaches
the surface, it won`t take long for temperatures to rise and thus,
afternoon highs are expected to rise 3-6 degrees above normal.

Changes really take place overnight tonight as the first band of
showers associated with the cold front will approach the mountains
tonight and shift east across the rest of the CWFA during the
beginning portions of the short-term period. As mentioned at the
beginning of the discussion, the front should be near the NC/TN
border by the very end of the near-term, but it almost seems as
if the latest guidance are showing hints of an anafront, which
displaces the precip behind the actual front. In this case, the
cooler air at the surface would undercut any stronger updraft from
developing within the band of showers overnight. Also, the better
forcing for ascent and deep layer shear resides north of the area,
so all indications suggest that the initial band of showers will
lack any real convective elements. Otherwise, widespread cloud
cover and dewpoints remaining elevated will keep overnight lows
5-10 degrees above normal.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 130 AM EDT Tuesday...

Key Messages:

1) A Cold Front Brings Isolated to Scattered Showers and
Thunderstorms on Wednesday

2) Breezy Northeast Winds and Drier Conditions Develop Behind the
Front Wednesday Night, Lingering through Thursday Night

3) Temps Remain Warm and Above Normal on Wednesday with Much Cooler
and Below Normal Temps Returning Thursday

Weak upper troughing remains overhead through the short term.
Meanwhile, at the sfc, a cold front tracks over the forecast area
Wednesday morning and afternoon before dry high pressure builds in
behind the departing front Wednesday evening into Thursday night
bringing drier conditions and much cooler temperatures. Breezy NE
winds will also develop behind the front Wednesday night into
Thursday night, ranging mostly from 15-25 mph.

00Z CAMs are not showing much in the way of coverage of convection
on Wednesday, depicting only isolated to scattered (at best)
activity. NBM depicts mostly chance PoPs (35% to 50%) across the
forecast area, although low-end likely PoPs (55%-60%) are in place
mainly along/east of I-77. PoPs on Wednesday may need to be lowered
in future updates if the CAMs continue showing anemic coverage of
convection. Most of the 00Z CAMs show the bulk of convection pushing
east of the forecast area by Wednesday afternoon but the 00Z NAMNest
appears to be the slow solution, keeping convection around across
the southern zones through Wednesday evening. With the NAMNest being
the outlier, only maintained low-end chance PoPs after 8pm
Wednesday. 30-35 kts of deep layer shear will be in place ahead of
the front with 00Z CAMs showing ~1,000-1,500 J/kg SBCAPE developing
east of the mountains during peak heating Wednesday. So, could not
entirely rule out an isolated strong storm or two east of the
mountains, but the severe weather threat should remain low with such
limited coverage of convection expected. Above normal highs return
Wednesday despite mostly cloudy skies and isolated to scattered
convection. Lows Wednesday night will end up 5-9 degrees above
normal thanks to lingering cloud cover. Highs on Thursday will be ~5-
10 degrees cooler across the mountains and ~10-15 degrees cooler
east of the mountains compared to Wednesday, ending up ~5-8 degrees
below normal. Lows Thursday night will end up near normal to a few
degrees below normal. With lows falling into the mid 30s across
portions the NC mountains Thursday night, patchy frost may develop.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 200 AM EDT Tuesday...

Key Messages:

1) Dry Conditions Stick Around as High Pressure Remains in Control

2) Breezy Northeast Winds Linger through the Weekend

3) Highs Remain Below Normal Friday before a Warming Trend Develops
this Weekend into Early Next week

Upper troughing remains in place on Friday before an upper low
strengthens and possibly cuts off from the main flow over/near the
eastern Carolinas this weekend. However, guidance is split regarding
the exact evolution and track of the low this weekend into early
next week. At the sfc, high pressure will remain in place over the
western Carolinas through early next week while a coastal low
develops off the Carolina coast late this weekend into early next
week. Again, guidance is not in the best agreement regarding the
exact evolution and track of this coastal sfc low, but it appears
(for now) that the western Carolinas should remain dry through the
period with the bulk of the moisture associated with the low
expected to remain east of the CWA. With this being said, there`s
still time for things to change so will continue to monitor the
forecast closely in the coming days regarding the evolution/track of
both the upper low and coastal low. For now, NBM keeps the area dry
which seems reasonable given the latest model guidance. Breezy NE
winds will linger through the weekend before lighter winds return
early next week. Highs on Friday will be similar to Thursday, ending
up ~4-8 degrees below normal. Lows Friday night will end up near
normal. A warming trend develops this weekend and lingers into early
next week. Highs will end up near normal to just below normal this
weekend, trending a few degrees above normal early next week. Lows
this weekend into early next week will end up a few degrees above
normal.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: MVFR/VFR cigs remain in place across the
NC terminals, while some clearing across the Upstate sites has
allowed for a LIFR/IFR low stratus to develop. This will limit
fog development, but with good moisture in place, can`t rule out
fog overnight tonight at all TAF sites as well. Placed a TEMPO
for either IFR/LIFR cigs at all sites between 06Z-13Z as guidance
suggest that cigs lower throughout the night into daybreak. Any
restrictions in place will gradually improve after daybreak as
all sites should return to VFR by the early afternoon hours, so
reflected a gradual improvement after daybreak at all sites. VFR
conditions will prevail through the rest of the forecast period, but
changes will be on the horizon with an incoming cold front. Winds
will be light through the period with more of a variable component
through daybreak and picking up a steady south-southeasterly
component at all sites after daybreak and remain this way through
the end of the TAF period. Can`t rule out an isolated shower during
the period, but confidence is too low on location and timing for
a TAF mention at this time.

Outlook: A cold front increases rain chances and restrictions,
through Wednesday night before drier conditions return for
the remainder of the week/weekend. Can`t rule out morning low
stratus/fog in the mountain valleys each day, but chances will
be lower than normal after Wednesday night through the rest of
the week/weekend.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...CAC
SHORT TERM...AR
LONG TERM...AR
AVIATION...CAC