799
FXUS62 KGSP 142323
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
723 PM 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 last half of the week.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 100 PM Sunday, key messages:

1. Most likely, all areas will remain dry through tonight, with
temperatures slightly above normal.

2. Increasing cloud cover overnight into morning, with isolated
showers over the mountains Monday afternoon.

3. Slightly cooler in most areas northeast of I-26 Monday owing
to cloud cover.

An upper low now near Jacksonville is in the process of
shearing off of the upper trough drifting off the East Coast.
The sfc low will drift north, promoting low to midlevel moisture
advection across much of NC by late Monday morning. The upper
low will drift slightly northward, and a vort lobe is progged to
round it and lead to DPVA shifting east to west across the
Carolinas late tonight thru Monday. Together, these developments
should bring increased high altitude cloud cover beginning in
the predawn hours, likely joined by lower cloud decks after
daybreak. The subsidence inversion weakens such that diurnal
mountain convection appears possible Monday, with ensuing
easterly upslope flow and the DPVA enhancing lift. A slight-
chance or isolated precip mention returns along the Blue Ridge
Escarpment, with mean flow vectors suggesting any propagation
would be toward the west or southwest from there.

Increasing clouds tonight reduce confidence in mountain valley fog
potential, although overall some areas of fog are still likely;
thinking is fog may just not be as long-lived as it was the
last couple of mornings. Cloud cover and/or weak CAA on NE flow
is expected to bring max temps back a little below normal over
the NC Piedmont and adjacent areas, but in the sunnier western
mountains and southern GA/SC zones, temps should be about the same
as Sunday`s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 1:25 PM EDT Sunday: The short-term fcst picks up at 00z on
Tuesday with a Rex block in place over most of the eastern CONUS.
This blocking pattern is expected to linger over our region thru
the short-term period, although it does gradually break down/Issi-
pate as the period wears on. At the surface, broad Canadian high
pressure will be centered north of New England as the period begins
late Monday. At the same time, another weak sfc low will have Dede-
loped just off the Carolina Coast and be spreading some amount of
Atlantic moisture over the Carolinas. Over the next couple of days
most of the latest model guidance has the low gradually moving over
the NC Coast and remaining there thru the end of the period late Wed.
Overall, no major changes were made to the fcst with a slight chance
for precip across most of our fcst area on Tuesday and a solid chance
over portions of the NC mtns and into the Foothills and Piedmont. On
Wednesday, precip chances have trended lower with only a slight chance
now fcst for portions of the NC mtns. No excessive QPF is anticipated.
High temperatures have trended a bit cooler on Tuesday, especially
over our NE zones where more cloud cover and stronger NLY flow is
expected. Temps are warmer on Wednesday but still expected to be a
few degrees below normal for mid-September.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 1:15 PM EDT Sunday: The extended forecast picks up at 00z on
Thursday with what`s left of a Rex-type blocking pattern lingering
over the eastern CONUS. By late Thursday, most of the latest guidance
has the Rex block dissipated. On Friday, broad upper trofing will
amplify over southern Quebec as another closed upper low develops
west of the Great Lakes. Over the weekend, this upper low is expec-
ted to drift eastward, yet it will likely remain well to our north
as flat upper ridging persists over the Southeast and mid-Atlantic.
At the sfc, weak low pressure will be centered somewhere over the
mid-Atlantic Coast as the period begins late Wednesday. On Thursday,
this system will lift further NE and dissipate. Over the next couple
of days, another sfc low is expected to develop somewhere over the
northern Plains and eventually move a weak cold front towards our
area. It remains unclear when this front will actually reach our
fcst area and how much impact it will have on our sensible wx. This
is partly because most of the long-range guidance has another robust
Canadian high migrating SE over the weekend. It`s not clear how far
south this high will spread and how much it will impact the approach
of the above-mentioned cold front. Regardless, the first half of the
period has trended drier with diurnally-driven slight chance PoPs over
the NC mtns on Thursday and Friday and solid chances for precip across
most of our fcst area over the weekend. Temperatures start out a few
degrees above normal on Thursday and remain above normal thru Saturday.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR conditions expected to prevail for the
most part at all sites. Tonight, winds become VRB and calm across
the majority of terminals. KAVL is the only site that could have a
brief IFR restriction for vsby as morning BR develops. With the
increased cloud cover throughout the night, confidence is rather low
but given the past few nights, not out of the question. Will keep a
TEMPO from 11z-13z for 2SM vsby. Winds after sunrise are slow and
should remain light throughout the TAF period. A mostly NE
directions is anticipated for the prevailing wind direction with a
few low-end gust possible Monday afternoon at KCLT. An isolated
shower is possible across the mountain terminals during the
afternoon, but confidence is too low for a mention in the TAFs.

Outlook: Mostly VFR outside of morning mountain valley fog and low
stratus through at least Tuesday. Rain chances increase across the
terminals Monday night, possibly lingering into mid to late week.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...Wimberley
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...CP