FXUS62 KGSP 111724
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1224 PM EST Mon Dec 11 2023

.SYNOPSIS...
Dry high pressure will linger over the area through Tuesday. A dry
backdoor cold front will arrive from the north on Wednesday, with
reinforcing cool high pressure returning through late week. Low
pressure is forecast to develop over the Gulf of Mexico during the
weekend and may affect our region late in the weekend or early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
1000 AM Update...The fcst is in good shape this morning and only
made minor tweaks to temps/dewpts. Expect occasional low-end gusts
across the non/mtns and moderate mtn valley gusts to persist thru
noon or so before the p/grad broadens and mixed-layered winds relax.

As of 615 am EST Monday: Mountain webcams around daybreak this
morning show very little snow still falling in the northwest flow
upslope areas, but IR enhanced cloud top temperatures still have
plenty of minus 10 to minus 12 values right along the Tennessee
border, so the scattered snow shower mention will continue for at
least a couple more hours. Winds appear to be settling down a little
bit from the peak gradient values last night, but a slight
resurgence is possible with heating and mixing. With plenty of
temperatures well down into the 20s across the mountains this
morning, the combination of a Winter Weather Advisory across the
northern mountains and an SPS for patchy black ice elsewhere in the
mountains still looks good.

Otherwise, the pressure gradient will steadily relax through the
day, with surface high pressure building over the southern
Appalachians by tonight. Cyclonic curvature persists in the upper
flow pattern through the period, with some channeled vorticity
moving through the area but producing little more than passing
cirrus. Max/min temperatures for today and tonight should run about
5 to 10 degrees below climatology.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
As of 215 AM Monday: Quiet weather expected thru the short term,
as sfc high pressure persists over the region under a dry confluent
upper-level flow. A dry reinforcing cold front will sag south
thru the area late Wednesday, as an upper trough digs over the
Northeast states. Perhaps an increase in mainly high clouds is
expected with the front Wednesday night, along with a wind shift
to N/NELY and marginally breezy Thursday. Temps will be a few deg
below normal Tuesday, back to near normal Wednesday, then return
to slightly below normal Thursday.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 230 AM Monday: The latest model guidance is still struggling
with a complex split-flow pattern across the US during the medium
range. The main players will be a closed low over the Four Corners
region, which will drift east into the Southern Plains by 12z
Saturday. Meanwhile, a shortwave is expected to ride thru a
relatively flat northern stream flow across the Northern Great
Plains. The GFS continues to be deeper with this northern stream
wave and causes it to phase with the southern stream low over the MS
Valley by late Saturday. This results in a deep low pres system
developing int he Gulf of Mexico, which spreads moisture north into
the Carolinas by early Sunday. The GFS has been showing something
like this fairly consistently over the lest few runs. However, the
ECMWF and Canadian do not phase the northern and southern streams,
resulting in the southern low just drifting slowly east and keeping
the resulting sfc reflection more suppressed to the south. The GFS
has less overall support among the medium range guidance, so the
fcst still reflects overall drier weather for our area. Even if the
GFS ends up being right, it looks too warm for too much of a wintry
p-type concern. Temps will start out a little below normal Friday,
then warm back to near normal Saturday. Depending on how much
moisture can spread in from the south/east, a cold-air damming event
may set up Sunday, returning temps to slightly below normal.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: A rather quiet TAF period with mainly SKC and
VFR conds thru the period. Moderate gusts at KAVL will begin to
weaken later this afternoon and maintain a modest nw/ly flow thru
04z. Elsewhere, occasional nw/ly to n/ly low-end gusts will linger
for a few more hours and weaken to VRB or CALM overnight. Winds
pickup sw/ly Tue and remain fairly weak thru the end of the period.

Outlook: Dry high pressure and VFR conds will persist through Friday.

&&

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

&&

$$
SYNOPSIS...HG
NEAR TERM...HG/SBK
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...SBK