453
FXUS62 KGSP 040641
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
141 AM EST Thu Dec 4 2025

.SYNOPSIS...
High pressure persists through late Thursday, resulting in dry
and chilly conditions.  Precipitation returns Thursday night
as temperatures grow even colder, resulting in a wintry mix
across the NC mountains and Foothills.  Precipitation chances
and below-normal temperatures linger through the first part of
next week.  Temperatures trend back toward normal by mid-week.

&&

.NEAR TERM /THROUGH 1 PM FRIDAY/...
As of 119 AM EST Thursday...

Key Messages:

1) Quiet but chilly weather continues through Thursday evening.

2) Wintry precip expected across the NC mountains and even parts
of the NC Foothills Thursday night into Friday morning, with a mix
of snow and freezing rain expected in the mountains, and mainly
snow expected in the Foothills.

3) Winter Weather Advisory, valid beginning 7PM Friday, has been
issued for most of the NC mountains.

A quiet night but cold night is underway across the forecast area,
as weakening high pressure remains in place across the Southeast.
Patches of cirrus continue to stream across the region, but
conditions are otherwise dry and clear.  Models briefly trended
toward dense fog developing across the Upstate overnight, but have
trended back away from that.  Dewpoint depressions of 1-3 degrees
are being reported south of NC-SC state line, however, so at least
patchy fog is still expected.  Morning low temps should drop into
the 30s across most NC zones, but may hover around 30 for much of
the Upstate.

A quiet day is in store for Thursday, as high pressure presently
centered over the northern Great Plains migrates eastward,
centering itself over New England by late this evening.
By this time, it`ll be perfectly positioned to induce classical
cold-air damming...providing much better support for a deep,
synoptically-enhanced surface wedge than the previous few systems.
Deep layer SW flow aloft, meanwhile, will intensify through the
day, with a lobe of southern stream energy pushing out of the
lower Mississippi Valley by tonight.  Strong isentropic ascent
looks to begin in earnest as early as 00z Friday, resulting a rapid
influx of low-level moisture within a baroclinic zone draped across
the Southeast.  So, expect weather to become increasingly active
after sunset.

As a result, a warm nose originating in Alabama and north Georgia
will advect into the Carolinas, arriving first in the southwest
mountains.  Here, precipitation will begin as rainfall, and by
the time the temperature drops below freezing, the warm nose
will already be in place, and so precipitation will change over
directly from rain to freezing rain.  Farther north, across the
northern Blue Ridge and NC Blue Ridge Escarpment, temps are likely
to cool down enough to support some snow before the warm nose
arrives, so precipitation will begin as rain or a rain/snow mix,
then transition to freezing rain after midnight.  Farther east,
much of the NC Foothills and even some parts of the northern
Piedmont will not see the arrival of the warm nose until near
or after daybreak...resulting in nearly an all-snow forecast for
these zones.  Thus...have hoisted a high-elevation Winter Weather
Advisory for most of the southwest mountains, valid from 7PM this
evening until 10AM Friday; for the northern Blue Ridge, issued
a zone-wide Winter Weather Advisory from 7PM tonight through 1PM
Friday.  For the Foothills, snow accumulations fall below an inch,
too little to warrant an advisory; but, will still highlight these
zones in the HWO, and may eventually issue an SPS as confidence
grows closer to the event.

Expect precipitation to continue into the first part of Friday
as CAD remains entrenched across the area, but it change over to
rain everywhere by late morning.  As the z500 forcing and low-level
isentropic ascent weaken and pivot eastward, some measure of drying
can be expected across the NC mountains by the end of the period
at 18z Friday.

&&

.SHORT TERM /1 PM FRIDAY THROUGH SATURDAY NIGHT/...
As of 1215 AM Thu:

Key message 1: Precip chances diminish Friday afternoon from
northwest to southeast, and remaining chances Fri night are for only
rain.

Dynamic lift gradually weaken through the latter half of the day
Friday with core of 250mb jet streak pushing off the Atlantic coast,
and the trailing, weaker streak being in an unfavorable position to
support lift over our area. 850mb winds veer such that advection is
more neutral or even cold-advective. Global deterministic models and
CAMs support little to no PoP after 18z, but the NAM and some
ensemble members keep precip going longer. Drying at 700mb implies
decreasing ice nuclei and lesser rates after that time, regardless.
CAD should be able to weaken slightly and temps warm enough to end
any wintry p-type threat east of the mountains. Still looking at an
exceptionally cold day though not as cold as previously forecast;
afternoon maxes mainly in the lower 40s aside from high elevations
and our northern couple tiers of NC Piedmont counties. Parts of the
northern NC mountains and Escarpment probably will remain wedged in
and below freezing much of the afternoon. Profiles aloft lack ice
nuclei and suggest only freezing rain for those areas after 18z,
amounts taper off and chances fall unmentionably low overnight.

Most models still largely depict the stalled front to our south being
activated yet again by the secondary jet streak and/or the next
shortwave. However, in most solutions that occurs too far south to
bring the QPF response into our CWA. For those that do show precip
coming back, however, we carry a 20-30% PoP mainly along/south of US
74. These models tend to be warmer so this PoP mention is carried as
only rain, with temps mainly in the mid 30s, and closer to 30 in our
north where PoPs are too low to mention. If precip were to spread
farther north than temps would likely be above freezing there also.

Key message 2: Precip chances ramp up again Saturday night. Light
freezing rain again may occur in the mountains, but otherwise only
rain.

Small PoPs Saturday persist in about the same arrangement as Friday
night, dropping slightly for a time in the US 74 corridor but
remaining 20-30% south of I-85, again because of a few guidance
members showing light precip via the frontal activation. The current
slate of deterministic models is split as to whether warm upglide
continues aloft, even if too shallow for precip. Cloud cover will
keep temps limited to the upper 40s and very low 50s over most of the
area, with wedge potentially hanging on.

Though the current slate of operational models is largely dry
Saturday night, yet another speed max develops at 250mb and once
again the stalled front could activate to our southwest, if not
Saturday night, Sunday morning. There are enough ensemble members
showing light precip creeping into the area to advertise a increase
in PoP to 20-25% in our north, and 30-40% in our south, Saturday
afternoon and night. On account of low confidence and the same idea
as the previous night--the wetter models tend to be warmer--have
confined FZRA mention to the northernmost mountains and Escarpment
where subfreezing temps are most likely to persist.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 115 AM Wed:

Key message 1: Small chances for rain remain in the forecast for the
Piedmont Sunday and Sunday night before the stalled front finally
exits the region.

Broad but full-latitude trough will cross the Mississippi Valley
Sunday and Sunday night, with embedded shortwave south of the Ohio
River. Models largely feature one last coastal cyclogenesis event
along the longstanding front which by then looks to be near the Gulf
Coast.  There remains spread as to when the low spins up, and some
solutions exemplified by the 04/00z GDPS which show the shortwave
digging farther south, and generating precip north of the front and
thus bringing activity into the CWA from the west as well as on the
periphery of the coastal low to our southeast. Chance (30-40%) PoPs
result for all zones Sunday and Sunday night primarily for that
reason. Previous model runs mostly were dry east of the mountains so
confidence insufficient to warrant PoPs any higher. Temps Sunday
similar to Saturday`s.

Key message 2: Next cold front looks to arrive late Sunday, bringing
a chance for northwest flow snow near the TN border, and colder
temperatures for all of the forecast area Monday and Tuesday.

Those models which had been showing precip Sunday-Monday had been
depicting the shortwave to cross the Appalachians of TN/NC in
clipper-like fashion and produce northwest-flow snow, where temps are
cold enough near the TN border.  Some solutions still feature that
without depicting chances from the coastal low, but the snow is still
featured late Sunday given that has been the more consistent
solution. Some FZRA mention on the eastern side of the mountains
where profiles are less favorable for snow. Elsewhere, all rain. PoPs
taper off Monday behind the front; max temps trend several degrees
colder than Sunday, being about 10 below normal. Monday night temps
reach the lower 20s in portions of western NC. Slightly warmer but
still cold max temps Tue.

Small PoPs redevelop Wed-Thu with low possibly pushing across the
Midwest and carrying another cold front into the area. Temps will
have rebounded close to normal and no wintry precip currently
expected east of the mtns.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Next round of thick cirrus is just streaming
into the upper Savannah River Valley and should arrive at KAVL and
Upstate sites within the next 1-2 hours.  Model guidance has backed
off on the notion of dense fog in the Upstate tonight, likely in
response to thicker forecast cloud cover; nonetheless, sites across
the area are reporting 1-3 degree dewpoint depression...which
means we`re close enough that it`s still a concern.  So, went
with MVFR to IFR fog/stratus mention in the Upstate and at
KCLT, rather than LIFR.  Can otherwise expect mostly light and
variable winds overnight, with continual periods of high cirrus.
Cloud cover will thicken on Thursday, becoming BKN by late morning.
Mid-level cloud cover will develop as expected through most of
the day.  Conditions will begin to deteriorate from west to east
after sunset, as rain steadily pushes in across the area and leads
to a quick reduction in flight category from VFR to at least IFR
everywhere by daybreak Friday.  This was handled in the TAFS mainly
with PROB30s for MVFR.  KCLT, given its longer 30 hour TAF period,
instead gets to prevailing MVFR with PROB30 IFR.

At KAVL: Expect more or less the same sequence of events as
described above, but it`s worth noting that toward the very end
of the TAF period, there`s a non-zero chance of FZRA and/or PL.
Chances for actually recording this are higher than with the
previous two winter precip events over the last week, so although
no mention of anything other than RA is currently carried in the
06z TAF, it`s not out of the question that it could be added at
some point.

Outlook: A lull in rainfall and flight restrictions is expected
late Friday into Saturday.  Unsettled weather will remain, however,
through the weekend and into the first part of next week.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Winter Weather Advisory from 7 PM this evening to 1 PM EST
     Friday for NCZ033-049-050-501-503-505.
     Winter Weather Advisory from 7 PM this evening to 10 AM EST
     Friday for NCZ048-052-053-059-063-064.
SC...None.

&&

$$

SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...MPR