251
FXUS62 KGSP 050356
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1056 PM EST Wed Dec 4 2024

.SYNOPSIS...
There will be a brief warm up ahead of a cold front which crosses
our area on Thursday.  After this front passes, expect temperatures
to drop first across the mountains then drop across the Piedmont by
late in the day Thursday. Temperatures remain well below normal from
Thursday night into Saturday.  A warmer and wetter pattern is
possible by the middle of next week.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 10:25 PM EST Wednesday: Other than some more frequent wind
gusts over portions of the Upstate and NC Piedmont, not much has
changed since the last update. The precip associated with the
approaching cold front currently looks pretty paltry to our west
and north, with considerably less coverage than earlier in the
evening. Temps remain in the low 40s across most of our CWA and
aren`t expected to drop much until later in the overnight.

Otherwise, the cold front still appears moisture-deficient as it
approaches our area and the better synoptic forcing still appears
to outrun the better moisture. Nonetheless, after midnight, there
may be enough moisture across the mtns for some light precipitation.
Despite the continued WAA this evening, no discernible warm nose
is expected to develop over the next several hrs. In addition, the
moisture will likely be shallow enough to prevent much in the way
of ice nucleation, such that the higher elevations where temps are
below freezing can expect minimal snow and possibly a glaze of ice
overnight. As the front pushes east of the mtns, these zones will
transition to a NW flow/CAA regime and some additional flurries
will be possible as the primary forcing mechanism transitions to
orographic lift via the mtns and very weak bndy-layer instability.
Moisture, however, will be minimal at this point, and any additional
snow accums should be minimal and mostly over the higher peaks and
ridges. Of more concern will be the low-level jet crossing the area
in conjunction with the core of stronger WAA. This should lead to
rapidly strengthening gusty winds during the overnight period. It`s
still looking like the central and northern Blue Ridge will be most
likely to see Advisory-criteria wind gusts, and even isolated High
Wind Warning-criteria gusts. The highest winds are still expected
over the northern Blue Ridge, which will be closest to the core of
the jet. No changes were made to the existing Wind Advisory for the
central and northern Blue Ridge, or the High Wind Warning for Avery
County. Winds should gradually taper off later Thursday morning and
into the aftn, as the LLJ pivots east and we transition to a gusty,
but less intense, post-frontal CAA regime. Any lingering moisture
will dry up quickly, and skies will clear again as broad Canadian
high pressure spreads over the area. RHs will fall into the low 30s
to upper 20s for much of the CWA, along with lingering 15 to 25 mph
gusts. Thus, a Fire Danger Statement has been issued for a portion
of our NC Piedmont and foothills from 11 AM until 5PM Thursday.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Key Messages:

1) Well below normal temperatures return Friday into Saturday with
dry conditions and generally light winds.

As of 130 PM Wednesday: Another shot of cold air will settle over
the region Thursday night, as a series of reinforcing shortwaves
dive thru the deep eastern CONUS trough. This will result in min
temps in the teens to mid 20s (similar to this morning`s lows). A
large area of sfc high pres will build into the Mid-MS and TN
valley, which means there will be enough of a pres gradient for
some lingering NW wind of 10-20 mph across the mountains. That
could bring wind chills close to 0 in the highest elevations,
but probably not enough coverage to warrant a Cold Weather
Advisory. Winds should decouple east of the mountains. Highs Friday
will be 10-20 deg below normal, despite sunny skies. The center of
the high reaches the forecast area by 12z Saturday, resulting in
optimal radiational cooling. So another chilly night with similar
lows to Thursday night in the lower elevations, but not quite as
cold in the highest peaks, as CAA subsides.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Key Messages

1) Temperatures gradually return to normal over the weekend,
possibly slightly above normal early next week.

2) A wetter and more unsettled pattern emerges early next week.

As of 220 PM Wednesday: The latest medium range guidance is in
good agreement on an upper level pattern change across the CONUS
starting over the weekend. The persistent eastern trough will
finally lift out to the NE, allowing an upper ridge to build in
across the Southeast. Upstream, the flow becomes split, with a
southern stream trough ejecting out of the Desert SW and a broader
trough over the Northern Rockies. The 12z guidance is in better
agreement on the southern trough lifting and shearing out as it
crosses the MS Valley. Then the northern stream trough takes over
and carves out a large longwave trough across most of the CONUS,
while ridging lingers along the East Coast. This will set up a moist
SWLY flow across the forecast area and should bring in rain chances
as early as Sunday night, but more likely Monday into Tuesday. At
this time, there is no strong signal for heavy rain or severe
weather, but confidence has increased enough to bump PoPs up into
the high-end likely to categorical range. Temps will be slightly
above normal for highs, and 10-15 deg above normal for lows. So,
no wintry precip types are expected.

&&

.AVIATION /04Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Expect VFR conditions to prevail thru the
00z taf period with few to sct mid and high clouds expected tonight
thru Thursday morning. Winds will remain gusty at most sites thru
the bulk of the taf period. As a cold front and preceding low-lvl
jet approach from the west, winds will strengthen tonight. At KAVL,
where winds will be essentially cross-valley, and thus weaker than
many other locations across the mtns, some low-lvl wind shear on
the order of 40kts is expected later tonight/overnight, from roughly
02z to 10z. KHKY also has a good chance of seeing some wind shear
from roughly 04z to 10z, although it may be more intermittent. I
don`t expect any precip at the taf sites as the front moves thru,
although the western Blue Ridge can expect some light accumulations.
Winds will gradually veer from SW to NW across the area on Thursday,
with KAVL becoming NW by late morning and the other terminals by the
afternoon. Winds will remain gusty into the evening especially over
the mtns.

Outlook: Gusty W/NW winds taper off Thursday night. Dry high
pressure will return on Friday and linger thru Sunday with VFR
conditions expected.

&&

.FIRE WEATHER...
A mostly-dry cold front is expected to cross the area tonight
into Thursday morning.  Winds will be gusty and erratic along
this front and in the dry air mass behind it, so gusts of up to
50mph are expected at higher elevations (see the Wind Advisory
and High Wind Warning bulletins for more information) Thursday
morning, and gusts of up to 25mph are expected virtually everywhere
Thursday morning and early afternoon.  During this same timespan,
extremely dry air behind the front will spill into the area and
result in relative humidity dropping into the low 30% to even upper
20% range.  Although winds are expected to taper off early enough
comapred to the RH drop that Red Flag conditions aren`t expected,
fire danger could still be an issue, especially with fine fuels
very dry across much of the region amid ongoing drought conditions.

After coordination with local land managers, a Fire Danger Statement
has been issued for North Carolina Forest Service Districts 2 and
10, which include most of the northern North Carolina Piedmont
and Foothills, as well as parts of the northern Blue Ridge.
This bulletin will be in effect from 11 AM thru 5 PM Thursday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...High Wind Warning until 4 PM EST Thursday for NCZ033.
     Increased Fire Danger from Thursday morning through Thursday
     afternoon for NCZ033-035-037-057-501>504.
     Wind Advisory until 4 PM EST Thursday for NCZ048>053-059-501-
     503-505-507.
SC...None.

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...JPT
FIRE WEATHER...MPR