I see GSP has indeed adjusted some, AFD now indicates WCs of down to -10 outside the mountains instead of -5. The point a click for me also shows 7 now instead of 11.
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FXUS62 KGSP 221942
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
242 PM EST Thu Dec 22 2022
.SYNOPSIS...
A band of precipitation associated with the arctic
front will sweep
through the area tonight with rain changing over to a brief period
of snow across the mountains and foothills along/north of I-40.
Dangerously cold air will quickly spill into the area by Friday
morning with gusty winds and subzero wind chills. Temperatures will
remain below freezing for most locations through Sunday morning
before gradual warming takes place very late this weekend into next
week with dry weather continuing.
&&
.NEAR TERM /THROUGH FRIDAY/...
Cloud cover will remain high across the non/
mtns this afternoon and
help keep temps below
normal. Across the
mtns, clouds have broken up
with dry air adv from the west and temps are running a little warmer
than
fcst/
d.
Expect all areas to cloud up this evening ahead of a dynamic arctic
cold
front progged to reach the wrn
NC mtns aft 08z. This
front will
bring a tight and lowering temp
gradient with enuf
moisture to
instigate snow showers across the
NC mtns. There may be a brief
period of sleet at onset, but the entire column
goes below zero very
quickly and transitions to all snow. Not expecting too much accum,
likely on the order of 1 to possibly 3 inches mainly affecting
elevations
abv 35000 feet. An advisory should not be needed and will
handle with an HWO mention for now.
The
front will drop temps quickly by 14z across the
NC mtns,
abt 40
degrees to the single digits and the -5 F to -10 F range over the
higher elevations. Temps will also drop to the lower 20s across the
non/
mtns by daybreak and then continue to drop into the upper teens
by the later afternoon. With very good llvl
CAA, descending and high
momentum air will be forced to the surface and create very strong
gusts, especially across the nrn
NC mtns where damaging gusts around
60 mph can be expected throughout most of the day Fri. A
High Wind
Warning has been issued there. Elsewhere, a Wind Advisory will be in
place into early
Sat.
With the combination of unusually cold air and strong winds, wind
chill values will drop dramatically across the mountains with
readings
abv 3500 feet dropping into the -20 F to
-30 F range and even lower at places like Grandfather
Mtn and Mt
Mitchell. Thus, a
wind chill warning has been issued at elevations
abv 3500 feet into Fri night. Elsewhere, solid
wind chill advisory
conditions will develop, meaning -10 F to -20 F across the
mtn
valleys and 0 F to -10 F values outside the
mtns into
Sat. This is a
good time to make sure exposed pipes are protected and contingency
plans are made for potential
power outages or dead car batteries,
such as ways to keep warm with layered clothing and ensuring current
contacts for possible assistance.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 200 PM Thursday: Potentially record breaking
wind chill
values will be in store Friday night as a brutal cold arctic airmass
settles in behind an arctic cold
front that sweeps through the area
early Friday. A deep stacked low centered over the Great Lakes
region will keep very cold thicknesses over the region through
much of the short-term. Very strong
CAA will filter in Friday
into Saturday and allow for very low
wind chill values overnight
Friday as a
Wind Chill Advisory has been issued for for locations
below 3500` feet in the mountains and across the Piedmont as wind
chill values range from 0F to -10F degrees. A
Wind Chill Warning
has been issued for locations above 3500` in the mountains with
values ranging from -20F to -40F degrees. With 850mb temperatures
between -15C to -25C degrees, expect actual temperatures to drop
like a rock with single digits possible across most locations in
the Piedmont and subzero values across the High Country, so record
lows will obviously be in jeopardy.
Temperatures tread slightly warmer for Saturday as the axis of the
stacked upper low slips east of the area. Very cold thicknesses
will still be in place, while the leading edge of a stout surface
high (~1040+
mb) works its way into the CFWA, while being centered
over the Great Plains. In this case, expect for highs to remain
below freezing for the most locations with teens and twenties in
the mountains, but winds will gradually subside outside of the
mountains on Saturday. Pressure
gradient remains relatively tight
over the mountains through Saturday night. As a result, another
Wind Chill Advisory may be needed, especially for elevations above
3500`. Thicknesses gradually rebound on Sunday as the stacked
upper low lifts into Atlantic Canada and surface high builds in
over the Lower MS Valley and Deep South. Expect temperatures to
"rebound", but values will remain 15 to 20 degrees below
normal
under
mostly sunny skies.