287
FXUS62 KGSP 092331
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
631 PM EST Tue Dec 9 2025

.SYNOPSIS...
Dry high pressure will cross our region from the west through
Wednesday then a cold front crosses our area early Wednesday night.
High pressure returns Thursday and into the weekend ahead of an
arctic cold front which arrives Sunday.  Dry and cold high pressure
will be in control of our weather early next week.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
As of 630 PM Tue:

Low clouds are lingering along the Blue Ridge into the NC mountains.
Low level moisture will be trapped under a strengthening inversion,
but strong drying takes place above it. Expect some locations to
remain cloudy overnight, especially where clouds are currently
lingering. Some low stratus may develop elsewhere. Lows will be
around 5 degrees below normal but could be slightly warmer where
clouds linger and slightly cooler where there area fewer clouds and
winds are light.

Key message 1: Strong wind gusts developing Wednesday morning.

850mb winds continue to ramp up overnight with LLJ advancing across
KY/TN thru daybreak, preceding the axis of the main shortwave
concurrently digging in the upper MS Valley. Higher elevations
look to see 15-25 mph winds develop by sunrise. Cloud cover will
be a bit tricky overnight, with potential for nocturnal cooling to
allow a very low fog/stratus layer to form, but drier/warmer air
also advecting in as low as 925 mb. Currently favoring clouds to
remain scattered enough to allow more rapid warming than we saw
Tue morning, which will allow mixing of strong winds to begin
early in the day. Most lower elevations look to experience
gusts to near 30 mph by late morning, with high elevations
exposed to 30-40 mph gusts by that time as core of LLJ passes
the mountains/foothills. Compressional warming and expectation
of sunshine will bring temps back into the 50s for most locations
in the afternoon; warmest areas may prove to be in the immediate
lee of major ridges where downsloping also has an effect. The
strongest 850mb winds are seen over the Piedmont during peak
heating, suggesting frequent 30-35 mph gusts and peak gusts for
the afternoon likely near 40 mph. Will add HWO mention with Wind
Advisory possibly being needed over the mountains; not confident
enough on advisory gusts to warrant mention for the Piedmont at
this time.

Key message 2: Northwest flow snowfall developing Wednesday
afternoon/evening near the Tennessee border.

Cold advection will begin following the LLJ passage; base of
shortwave progged to pass the Appalachians by around 00z Thu. Winds
turn westerly during the afternoon along the TN border, and to
the NW near the base of the trough, with accompanying upslope
moisture. Surface temps should fall rapidly over the mountains by
sunset; top of the moist layer will approach favorable temps for
ice nucleation, with cooling overcoming the increasingly shallow
moisture overnight. The most favorable locations, isolated peaks
nearest the TN border, are expected to see 2-3" snow by 12z
Thu. However, farther from the border, lower QPF translates to
lower amounts, and zone averages in the border counties are low
enough (even in areas above 3500`) to warrant a Winter Wx Advisory
at this time. Will also add/refine HWO mention for the snow.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
As of 1205 PM EST Tuesday...

Key Message #1: Breezy conditions linger into early Thursday,
especially at higher elevations.

Synoptic and regional guidance depict mostly weakening low-level
winds by Thursday morning.  Though the core of the LLJ will now be
well to our east, and most if not all of the forecast area subject
to a postfrontal CAA regime...low-level winds may not peak until
shortly after daybreak Thursday, before slowly weakening through
the day.

The result will be a continuation of Wednesday night`s breezy
conditions into the first part of Thursday.  In mountain valleys
and at lower elevations, the gusts should mostly be over by Thursday
morning; at higher elevations, however, which will protrude directly
into the CAA layer, gusts will continue past the overnight and
into Thursday morning.

Key Message #2: Northwest flow showers and flurries develop
Wednesday night along the NC-TN state line.

In tandem with the CAA regime, lingering low-level moisture
across the Appalachians will produce scattered NW flow snow
flurries...continuing past 12z Thursday.  Though overall coverage
will be lower than during the overnight, operational guidance
depicts enough moisture to justify a slight chance PoP across the
northern Blue Ridge early Thursday.  By the afternoon, moisture
should continue to retreat north, and precipitation should come
to an end.  Little to no accumulation is expected past 12z Thursday.

Key Message #3: Cooler-than-normal temperatures on Thursday begin
to warm back toward normal on Friday.

As postfrontal high pressure slides east across the lower Tennessee
Valley on Thursday afternoon, the initial result will be a decrease
in temperatures across the western Carolinas as the cooler air mass
slides into place.  It should remain fairly progressive, however,
approaching the Atlantic coast on Thursday night and Friday.
A southwesterly return flow should develop, and operational guidance
depicts slow onset of low-level WAA late Thursday night, followed
by more vigorous flow on Friday.

As a result...generally expect temperatures at least a category
below normal on Thursday, with highs in the mid- to upper-40s in
most areas, possibly hitting 50 in a few spots across the Savannah
River Valley and southern Upstate.  Temperatures will crash into
the mid-20s Thursday night, before rebounding to the mid-50s,
within a category of normal, on Friday afternoon.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 1153 AM EST Tuesday...

Key Message #1: Anomalously warm conditions on Saturday as a cold
front approaches from the west.

Friday night and Saturday, probabilistic guidance depicts an
ill-defined cold front advancing out of the Ohio Valley into
the Carolinas, resulting in a weak round of low-level CAA across
the area.  Despite some elevated flow aloft - 30-35kt z850 flow
according to some operational guidance - the consensus is that
most zones will remain decoupled enough so as to prevent any of
this wind from mixing down to the surface...and in turn, the low
elevations as well as the mountain valleys generally look to have
quiet winds Friday night and early Saturday, where only the higher
peaks may continue to see breezy winds by virtue of simply being
closer to the actual CAA layer.

On Saturday, WSW flow will continue, and downsloping will
contribute early in the day to warmer temperatures, partially or
completely offsetting any cooling due to CAA.  By mid-day, winds
should toggle more decidedly to the S/SW, resulting in weak WAA
and further contributing to warmer temps on Saturday.  All told,
most of the area can expect to see highs some 1-2 categories warmer
than climo...the upper 50s for the low terrain, or even the lower
60s south of I-85.

Key Message #2: Scattered showers and some high-elevation snow
develops over the region Saturday night.

Prefrontal WAA and associated moisture flux will continue
into Saturday night as a shortwave axis extending from the NC
Appalachians northward into Pennsylvania crosses the region.
The better forcing will remain well to our north over Virginia
and the Cumberland Plateau, but we can still expect some
precipitation to develop after 00z Sunday.  For the bulk of the
area, confidence is high that this will be all rain; however,
for higher elevations across the NC mountains, rain may change
over to snow as temperatures cool.  Accumulations should be very
light, and confined to the highest elevations.  It`s not entirely
out of the question that isolated spots across the NC Foothills,
mainly north of I-40, could see brief flurries Sunday morning,
but certainly no accumulations are anticipated here.

Key Message #3: A cold front arrives Sunday and ushers in a much
colder air mass for the start of next week.

Any WAA on Saturday will quickly end Saturday night, as a
more well-defined frontal boundary swings out of Tennessee.
Postfrontal CAA will develop during the wee hours of Sunday morning,
but present guidance suggests it will not become maximized until
well into the day Sunday, or even Sunday evening.  So, highs
on Sunday will be closer to normal, but not especially cold.
By Sunday night, however, robust CAA will usher in a much colder,
largely unmodified continental air mass...and lows will fall into
the mid- to lower-20s across most the forecast area, with some
higher peaks in the Appalacians even falling into the teens.

On Monday, much of the forecast area may only recover into the
upper 30s or lower 40s, before falling back into the 20s that
night...which should be an excellent one for radiative cooling.
However, past this time the air mass should quickly begin to modify.
Ensemble guidance suggests temperatures could be back within a
category or so of normal again by the end of the seven-day forecast
on Tuesday.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Sat pix show MVFR stratocu dissipating near
KHKY but redeveloping at KAVL. Have a short period of MVFR for both
this evening...but that may need to be extended. Mainly cirrus with
patchy MVFR or low VFR elsewhere. Light S to SW wind most locations
as well. Guidance still shows drying is likely to continue above the
PBL overnight, an inversion will be reinforced nocturnally. A
shallow moist layer could lead to an MVFR to IFR deck forming
overnight; increasing winds appear to be the main limiting factor in
that occurrence. For now, IFR cig only included at KAND. LLWS threat
increases toward daybreak and is mentioned at KCLT/KGSP/KGMU/KAVL at
some point between 08z and 18z. Too intermittent in guidance to
warrant inclusion at KHKY or KAND with this set. Strong gusts of 20-
25 kt likely with morning warming, assuming cigs do not form
overnight. All sites likely to see 25-30 kt winds after noon with a
few peak gusts of 35-40 kt possible.

Outlook: NW flow snow showers along the NC/TN border Wednesday
night and again Thursday night into Friday; MVFR cannot be ruled
out at KAVL in those periods. Likely VFR and dry elsewhere through
the weekend.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JCW/RWH
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...RWH