112
FXUS62 KGSP 311102
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
702 AM EDT Sun Aug 31 2025

.SYNOPSIS...
High pressure will settle along the east coast later today and build
south across the area. The high will gradually weaken but linger
through the middle of the week.  A few showers and thunderstorms
are possible each day across the mountains, with the greatest
coverage expected Thursday, as a cold front approaches from the
west. Temperatures remain below seasonal normals through the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 3 AM EDT Sunday: Expansive high pressure over the Great
Lakes will build south and eastward along the Atlantic seaboard
today. Meanwhile, a very weak stationary front lingers across the
Piedmont of the Carolinas. This boundary is characterized mainly
by a 2 to 4 degree dewpoint gradient and a shift from calm winds
south of it to light northeast winds north of it.

Aloft, anomalous troughing persists across the eastern CONUS as
shortwave disturbances rotate through the base of the longwave
trough. Our forecast area also lies near the left-exit region of a
jet streak extending from the southern Plains into the Tennessee
Valley. The combination of synoptic ascent and low-level upslope
flow will support scattered showers this afternoon, mainly across
the mountains.

At the surface, strengthening high pressure east of the Appalachians
will set up a hybrid cold-air damming event, with an inverted
trough becoming better defined along the Blue Ridge into eastern
Tennessee. Convergence along this boundary, combined with typical
terrain circulations, will provide an additional focus for showers
during peak heating. Rain falling into a somewhat dry airmass near
the Blue Ridge will promote evaporative cooling, reinforcing the
cool wedge across the escarpment and foothills. While not nearly
as strong as the early August CAD event, this setup will hold
temperatures 4 to 8 degrees below normal today.

Despite a few hundred J/kg of surface-based CAPE, profiles are
very narrow, especially above a mid-level inversion. This will
limit updraft depth and strength, keeping thunder chances minimal
despite the large-scale support. Most convection should remain
confined to the mountains, though a few showers may drift into
the NC/SC foothills late in the day with passing shortwave energy.

Showers should diminish with the loss of heating this evening,
although activity may linger a bit longer than typical across the
Blue Ridge with additional upper-level support. The overnight
fog potential appears low, with mid-level debris clouds behind
afternoon convection limiting radiational cooling.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 135 AM EDT Sunday: An upper low will be centered over the
Delmarva Peninsula to start the short term, with a vigorous
shortwave trough diving SE across the Mid-MS Valley. As that
trough enters the TN Valley, it will flatten the flow atop the
forecast area. More energy dives in behind that wave Tuesday,
carving out a deeper mean longwave trough across the eastern
CONUS. At the sfc, a dry high pres system will persist along
the East Coast, but gradually weaken. A NELY low-level flow will
keep things pretty stable, except for the western NC mountains,
where enough moisture pools to support at least isolated diurnal
convection. Temps will continue to be 5-10 deg below normal across
the area with comfortable humidity.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 145 AM EDT Sunday: A deep upper low will drop south into the
western Great Lakes Wednesday and further carve out the persistent
eastern CONUS trough thru Friday, with the axis setting up over
the MS to TN valley regions.  From there, the low should start to
lift north and the trough will begin to deamplify, but persists
thru at least Saturday. The digging trough will bring a cold front
into the OH Valley Wednesday, which is forecast to push thru the
forecast area late Thursday or Thursday night. SLY to SWLY flow
ahead of the front will tap into a little moisture, but overall,
forcing will be strongest to our north and guidance is not that
excited about QPF potential. Also, a coastal low is progged to form
invof FL and track NE, which may disrupt moisture transport east
of the mountains. So most of the PoPs will remain in the mountains
Thursday thru Thursday night. The LREF probs of >0.5" of rain is
basically less 15% with the fropa across the CWFA.  There may be
enough overlap of shear and instability with the front to support
a non-zero severe tstm threat, with damaging wind gusts being the
main threat. But confidence this far out is still low.  There is
uncertainty on how much things dry out Friday, but guidance in good
agreement that drier weather reaches the area by Saturday. Temps
will remain below normal thru the period, warmest/closest to normal
Thursday, then cool slightly behind the front.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Stratus deck has yet to materialize in the
western NC terminals, including CLT, HKY, and AVL, although there is
evidence of it farther north. This is likely due to the extensive
mid-level clouds that have been around much of the night. However,
there is still a brief period for MVFR or IFR restrictions at
the start of the 12Z TAF period, lasting for an hour or two at
most. Confidence not high enough to include restrictions in the
forecast except for at HKY since they are located nearby the
southern edge of the stratus deck, so it wouldn`t take much to
get there.

Winds will remain light NE overnight, then increase toward
daybreak as high pressure surges down the eastern slopes of the
Appalachians. Expect speeds to peak 8-12 kt with a few gusts
around 15 kt through late morning before easing slightly this
afternoon. Similar to Friday, scattered showers are expected
mainly in the mountains during the afternoon. KAVL carries a
PROB30 for showers, but confidence remains too low to include at
other terminals.

For tonight, debris clouds from afternoon convection again
complicate fog potential. The more likely scenario is for stratus
redevelopment across mountain sites, while Piedmont terminals
should remain VFR.

Outlook: Scattered afternoon/evening convection will continue
into early next week, mainly across the mountains, with coverage
possibly spreading east midweek. Nocturnal valley fog and/or
low stratus will also be possible each night and early morning,
especially at mountain terminals.

&&

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

&&

$$

SYNOPSIS...ARK
NEAR TERM...JK
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JK