603
FXUS62 KGSP 140538
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
138 AM EDT Sun Sep 14 2025

.SYNOPSIS...
Dry high pressure remains over the region through Monday. A
developing low pressure system along the Carolina coast may bring
rain to our area for the middle of the week. Dry high pressure
returns for the end of the workweek.

&&

.NEAR TERM /THROUGH TONIGHT/...
As 120 AM EDT Sunday...

Key Messages:

1) Mountain Valley Fog and Stratus Expected this Morning, Possibly
Developing Again Monday Morning

2) Slightly Warmer and Dry Today East of the Mountains

3) Isolated Showers May Develop Across the Mountains Today but
Confidence is Low

4) Upper Cloud Cover Increases this Afternoon into Tonight

Upper troughing remains in place today before a closed upper low
develops over the Carolinas this evening into tonight. At the sfc,
weak high pressure remains over the Southeast while a coastal low
develops offshore the Carolinas.

Lows this morning will end up a few degrees above normal across the
mountains and a few degrees below normal east of the mountains.
Mountain valley fog is expected again this morning, lifting an hour
or two after sunrise as daytime mixing develops. Mostly dry again
today but a few spotty showers may pop up over the mountains per
some of the 00z CAMs. However, confidence remains low so maintained
a dry forecast. Today`s highs will end up a few degrees normal
despite upper cloud cover gradually increasing this afternoon. Highs
across the mountains will be similar to yesterday. Highs east of the
mountains will end up a few degrees warmer compared to yesterday.
Wind speeds will be a bit lighter compared to yesterday.

Mountain valley fog and low stratus may develop again tonight into
daybreak Monday but confidence is low as scattered to broken cirrus
should limit radiational cooling somewhat. Lows Monday morning will
end up a few degrees above normal area-wide thanks to lingering
cloud cover.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
As of 115 AM EDT Sunday: The guidance looks to be coming into better
agreement regarding the developing Carolina coastal low and the
resultant precipitation/sensible weather. That said, there are still
some significant differences to resolve. The upper low develops along
the SC coast and moves northward into the Coastal Plain of the
Carolinas Monday into Tuesday then moves north away from the area
Wednesday. The associated surface low forms off the NC coast Monday
and moves into the Coastal Plain on Tuesday then moving north of the
area on Wednesday. The GFS has come on board with this plan, but
still keeps the low farther east limiting the amount and coverage of
showers developing in the moist, easterly flow. That said, the
Canadian has trended eastward with its low as well. The NAM and the
12Z ECMWF are farther west bringing more coverage and higher QPF.
Given these differences, the model blend PoP and QPF remain the
better choice, with chance PoP moving into the I-77 and I-40
corridors and along and near the Blue ridge with the moist, easterly
flow Monday night into Tuesday. Slight chance PoP for the upstate
but little to no chance for the Upper Savannah River valley. Precip
chances diminish from west to east Tuesday night with some lingering
slight chance PoP Wednesday along the Blue Ridge and I-40 corridor.
QPF during all periods will be light. All the guidance shows little
to no instability during this period, so the chance of thunderstorms
is very low. Highs near normal Monday fall below normal where clouds
and precip move in but remain near normal over the western sections
where clouds and precip are less likely. Highs bounce back Wednesday
but remain below normal over the I-77 corridor. Lows will be a few
degrees below normal.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
As of 130 AM EDT Sunday: A short wave ridge builds over the area
into Friday. Heights then slowly fall Saturday as a trough
associated with an upper low over the Midwest moves eastward. At the
surface weak high pressure returns over the area through Friday, but
weak moisture return may develop across the mountains. Better
moisture increases develops Saturday ahead of a frontal system
associated with the upper trough moves toward the area. This would
lead to scattered diurnal convection, mainly across the mountains on
Saturday. Highs rise to around 5 degrees above normal by Friday then
drop a couple of degrees on Saturday. Lows remain around normal.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR through the 06Z TAF period outside of
mountain valley fog and low stratus this morning. Have a TEMPO at
KAVL for LIFR restrictions from 09Z-13Z as fog and stratus will lift
an hour or two after sunrise. Mostly dry through the period as well,
although a few isolated showers may develop across the mountains.
Once again, confidence is low so maintained dry conditions at KAVL.
Winds east of the mountains will generally be light and N/NNE to
calm this morning before toggling more NE/ENE this afternoon into
early this evening. Wind speeds will be a bit lighter today compared
to yesterday, ranging from 3-7 kts. Winds east of the mountains go
light again this evening into tonight, toggling back to a more N/NNE
direction late this evening into tonight. Wind speeds at KAVL will
remain light through the TAF period. Calm winds should continue at
KAVL through daybreak, picking up out of the N/NNW after sunrise.
Winds at KAVL will return to light and VRB to calm this evening into
tonight. Some VFR cu may develop again this afternoon/early evening.
Coverage of cirrus will gradually increase today into tonight,
becoming SCT to BKN.

Outlook: Mostly VFR outside of mountain valley fog and stratus each
morning through at least Tuesday. Mostly dry outside of some
isolated mountain showers on Monday. Rain chances increase Monday
night, possibly lingering into mid to late week, but confidence is
low.

&&

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

&&

$$

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