506
FXUS62 KGSP 050743
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
243 AM EST Wed Feb 5 2025

.SYNOPSIS...
Cooler weather returns today as cold air damming briefly develops
east of the mountains. Unsettled weather and warmer temperatures
return on Thursday and linger into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 156 AM Wednesday: Perturbed quasi-zonal flow will be the name
of the game today and tonight. A belt of westerlies is draped from
the Great Basin to the Southern Appalachians. Early morning water
vapor imagery depicts the presence of an embedded flat shortwave
trough sliding across the Four Corners region. Guidance is in good
agreement that the trough will propagate across the Central Plains
and into the Middle Mississippi Valley today and across the Ohio
Valley and eventually the central Appalachians tonight. Meanwhile,
at the surface, sprawling high pressure extending from the Northern
Plains into the Great Lakes region will shift into New England.
Ageostrophic adjustment to the low-level flow has already sent a
backdoor cold front through the area early this morning and the
onset of Cold Air Damming. The CAD regime will strengthen through
the day with plentiful cloud cover developing across the region. A
couple stray showers will be possible atop the cold dome, but most
locations will remain dry beneath neutral height tendencies. The
most notable impact from the CAD will be in regards to temperatures
as cool northeast flow and aforementioned cloud cover keep highs in
check. Northeast portions of the area will struggle to reach 50 with
low to upper 50s elsewhere. This will be 20-30 degrees colder
compared to the record warmth yesterday.

The previously mentioned shortwave trough will pass by to the north
tonight with only nebulous forcing extending this far south.
Nonetheless, a strengthening low-level jet and modestly favorable
upper jet dynamics will allow for showers and a couple thunderstorms
to blossom over north Georgia and eastern Tennessee this afternoon.
With time, these showers and storms will make a run at the area late
this afternoon into this evening. Continued upstream redevelopment
within westerly flow will support the potential for showers and a
couple storms to continue to stream into the area through the
overnight hours as well. Surface high pressure will slowly nudge
offshore overnight, but will maintain enough influence that
significant erosion of the cold dome is not expected by daybreak
Thursday morning. If anything, diabatic effects from precipitation
will help to reinforce the cold dome. Thus, any showers and storms
will be elevated above the CAD inversion. Forecast soundings depict
a couple hundred J/kg of MUCAPE above the inversion layer, thus the
potential for a few lightning strikes within any deeper convective
updrafts that are able to penetrate high enough above the freezing
level for charge separation within the mixed phase region.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 200 AM EST Wednesday...

Key Messages:

1) Cold Air Damming Gradually Erodes on Thursday

2) Breezy Southwest Winds Develop on Thursday

3) Well Above Normal Temperatures Expected

Quasi-zonal flow will remain aloft through the short term. At the
sfc, cold air damming will gradually erode late Thursday morning
into Thursday afternoon while a warm front lifts north over the
forecast area and as a cold front approaches from the northwest.
CAMs depict ongoing convection across mainly the western half of the
forecast area Thursday morning, with convection expected to linger
over the NC mountains through at least late Thursday night. Thunder
chances will be limited to the NC mountains Thursday morning as cold
air damming will limit instability east of the mountains. Thunder
chances will linger through late Thursday evening across the NC
mountains as drier conditions are generally expected east of the
mountains during this timeframe. With cloud cover expected to
gradually thin out as the wedge erodes, and with SW`ly flow in place
behind the warm front and ahead of the cold front, highs on Thursday
will rebound back to ~15-20 degrees above normal. Temperatures will
climb into the upper 60s to lower 70s across the lower elevations
and the mid 50s to lower 60s across the higher elevations. Breezy SW
winds will linger across the mountains through Thursday, with breezy
winds expected to develop east of the mountains by Thursday
afternoon. Winds will remain well below advisory criteria thanks to
the WAA regime. Breezy conditions will linger through late Thursday
night. Lows Thursday night will end up ~20-25 degrees above normal
thanks to W/SW flow and lingering clouds.

Any lingering gusts will gradually taper off throughout Friday
morning as the front tracks across the northern half of the forecast
area. The front looks to hang up across the middle of the forecast
Friday afternoon into Friday night. Meanwhile, the southern
periphery of a sfc high will try to build in behind the front from
the north Friday into Friday night across the northern half of the
CWA. This should allow for the northern zones to remain mostly dry
while the southern zones could continue to see scattered showers.
Capped PoPs to chance Friday into Friday night for now. Slightly
cooler temps are expected across the mountains on Friday behind the
front but temps east of the mountains will be similar to Thursday`s.
However, highs are still expected to end up ~15-20 degrees above
normal again.  Lows Friday night will be slightly cooler compared to
Thursday night, but still ~15-20 degrees above normal thanks to
increasing cloud cover.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 230 AM EST Wednesday...

Key Messages:

1) Unsettled Weather Continues

2) Well Above Normal Temperatures Linger through the Weekend

3) Cooler and Below Normal High Temperatures Return Early Next Week

Upper quasi-zonal flow remains overhead through the weekend. Spotty
showers should linger through Saturday evening as the cold front
remains stalled across the forecast area. Capped PoPs to chance
during this timeframe for now as the latest global model guidance
sources are not in agreement regarding the coverage of precip.
Saturday should have a weak cold air damming like feel to it thanks
to broad sfc high pressure stretching from the Great Lakes to the
Mid-Atlantic the first half of Saturday. This will allow mostly
cloudy skies and E/NE`ly sfc winds east of the mountains to
continue. As a result, much cooler (but still ~5-10 degrees above
normal) temperatures expected east of the mountains Saturday
afternoon. Highs east of the mountains will drop into the upper 50s
to mid 60s along and east of I-26 with the mid 60s to lower 70s west
of I-26. Highs across the mountains will range from the lower 50s to
lower 60s. Lows Saturday night will rebound back to ~20-25 degrees
above normal thanks to SW`ly flow and lingering cloud cover. Breezy
winds should develop across the mountains on Saturday ahead of an
approaching cold front, lingering through Saturday night. Breezy
winds look to develop east of the mountains by Saturday night.
Breezy conditions will linger through Sunday morning before
gradually tapering off Sunday afternoon. The cold front will also
increase rain chances Saturday night into Sunday, mainly across the
mountains, as it tracks towards and across the forecast area. This,
have likely PoPs painted across the western NC mountains Saturday
night into Sunday morning. The front should push south of the area
Sunday evening into Sunday night, possibly allowing drier conditions
to briefly develop. However, maintained chance PoPs area-wide as
some of the latest model guidance maintains PoPs Sunday night. Thus,
confidence on PoPs will be low during this timeframe. Highs will
rebound back to well above normal values (~15-20 degrees) on Sunday,
climbing into the low to mid 70s east of the mountains. Highs in the
mountains will range from the low 50s to mid 60s. Lows Sunday night
will be cooler compared to Saturday night, but still ~12-17 degrees
above normal.

Much cooler and slightly below normal temperatures return Monday,
with highs only reaching into the upper 40s to mid 50s east of the
mountains. Highs across the mountains look to range mostly from the
low 40s to mid mid 50s. Highs will drop to several degrees below
normal by Tuesday, with temps only ranging from the mid 40s to low
40s across the lower elevations. Higher elevations will only see
temps reach into the mid 30s to low 40s. The unsettled pattern will
continue into early next week as another cold front approaches from
the west on Monday before tracking a across the forecast area on
Tuesday. This may lead to widespread precip developing the second
half the the long term. Capped PoPs to chance on Monday, with likely
PoPs Monday night into Tuesday. Temps look to drop near or below
freezing across portions of the NC mountains and along/near the I-40
corridor Monday night into Tuesday so some p-type issues look
possible. However, with this being towards the end of the forecast
period, confidence remains low. All liquid precip is expected
elsewhere as temps should remain above freezing. Lows will remain a
few to several degrees above climo each night thanks to cloudy skies
and precip.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR conditions are ongoing across the area
and are expected to prevail through much of the overnight hours as
mainly high clouds stream overhead. Restrictions return during the
pre-dawn hours as ceilings lower with MVFR common at most terminals.
IFR ceilings may become more widespread by the end of the TAF period
early Thursday morning as ceilings lower further. Otherwise, at
least scattered showers are anticipated to move across the area late
this afternoon and into the evening. Temporary visibility
restrictions will be possible with any of this activity. Winds will
generally be out of the northeast with the exception of KAVL which
will be out of the southeast.

Outlook: Periodic showers possible through the weekend and could
bring associated restrictions to visibility along with
periods of low ceilings.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...TW
SHORT TERM...AR
LONG TERM...AR
AVIATION...TW