216
FXUS62 KGSP 310814
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
314 AM EST Fri Jan 31 2025

.SYNOPSIS...
A low pressure system will bring a cold front across our area today,
accompanied by widespread showers and perhaps an isolated
thunderstorm. Drier weather returns this weekend into next week
along with warming temperatures with the exception of Sunday.
Temperatures are expected to climb into the low and eventually mid
70s by early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM EST Friday...

Key Messages:

1) Air Quality Alert in Effect for Mitchell, Yancey, Burke, and
McDowell Counties Until Midnight

2) Rain Returns Today Ahead of a Cold Front

3) Well Above Normal Temperatures and Breezy Winds Expected

Thick upper cloud cover is in place across the forecast area and
scattered showers continue across the NC Piedmont and SW NC
mountains this morning ahead of a warm front. Showers will gradually
taper off through the next few hours leading to brief drying ahead
of an approaching cold front. Lows this morning will end up ~12-15
degrees above normal thanks to cloud cover limiting radiational
cooling. An Air Quality Alert remains in Effect for Mitchell,
Yancey, Burke, and McDowell Counties through Midnight tonight for
fine particulates.

The cold front will track across the forecast area this afternoon
and evening allowing widespread rain showers to develop from west to
east. Despite cloudy skies and widespread precip, highs will end up
~10-15 degrees above climo, with temps climbing into the lower 70s
south of I-85. Although the front and precip will be moving through
during peak daytime heating hours, thick cloud cover will make
destabilization hard to come by. Both high-res and global model
guidance sources show little in the way of SBCAPE (isolated pockets
of ~50 J/kg or less). This is good news as an impressive 80-100 kts
of bulk shear will be in place ahead of and along the cold front. A
few rumbles of thunder cannot be entirely ruled out this afternoon
and evening (thanks to elevated instability) but the severe weather
potential looks to remain minimal, if any. S/SW winds will gradually
increase ahead of the front becoming breezy. However, gusts will
remain well below advisory criteria. Wind gusts will remain elevated
across the mountains through tonight, as flow turns W/NW`ly behind
the front, but will gradually taper off east of the mountains this
evening. Drier conditions are expected to develop from west to east
late this afternoon into this evening behind the departing front.
Cloud cover will gradually diminish east of the mountains as well
but will linger along the NC/TN border thanks to upslope flow. Lows
tonight will once again end up ~10-15 degrees above normal.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 149 AM Friday: The weekend kicks off with a compact shortwave
trough quickly racing offshore while broad quasi-zonal flow settles
across much of the country in its wake. Heights gradually rise
through the weekend as broad upper ridging builds from northern
Mexico across the Gulf and into the Caribbean. This will foster a
warming trend on Saturday with highs returning to the low to mid 60s
across much of the area, especially east of the mountains. Sunday
will be the sole exception to the warming trend as a transient
surface high quickly translates across New England. This will result
in a brief period of cold air damming Saturday night into Sunday as
the ageostrophic response to topographically blocked anticyclonic
flow sends a backdoor front through the area overnight. Sunday
morning will start off in a wedge pattern, but the progressive
parent high will quickly shift offshore during the day allowing for
flow to shift back to out of the south. This should bring a quick
end to any damming regime through the day, but will likely be
sufficient to keep temperatures a number of degrees cooler compared
to Saturday.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 204 AM Friday: A notable warming trend will continue into next
week as the synoptic pattern remains largely stagnant through at
least Tuesday night. Progressive northern stream flow will remain
draped across the far northern tier of the country with persistent
zonal westerlies extending from the Four Corners to the Carolinas.
Heights will also continue to slowly rise as a stout upper ridge
builds over Cuba. Temperatures will climb well above average Monday
and Tuesday with highs soaring into the low to mid 70s. Upper flow
finally becomes more perturbed by midweek as a southern stream
trough moves onshore along the west coast and into the Great Basin.
A lead piece of energy embedded within increasingly southwest flow
is progged to lift across the Ohio Valley on Wednesday. A few
associated showers may scrape the mountains, but the presence of
considerable ridging over the southeast states should shunt greater
forcing north of the area with most locations remaining dry. Cloud
cover may briefly slow the warming trend as well.

By late week, amplifying upper trough dropping out of the Canadian
Prairies will help to suppress the southeast ridge and send a strong
cold front through the Great Plains into the Midwest. Compressional
warming ahead of the encroaching boundary will allow for a return of
temperatures in the 70s. Forecast confidence rapidly wanes by Friday
into the weekend, however, with regards to timing of the front and
southward progression. The Southern Appalachians will remain on the
southern flank of the upper trough with only glancing forcing. With
time, as the front pushes southeast, it will eventually become
oriented parallel to broader westerly flow in the base of the mean
synoptic trough. This has resulted in a slower trend with the front
not arriving until Friday or Saturday, if at all, depending on one`s
ensemble cluster of choice. This will have further implications on
sensible weather with a resulting large window of slight chance to
chance PoP until the timing can become better refined.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Some -SHRA continues tracking across western
North Carolina this morning but dry conditions are now expected for
all terminals through daybreak. Winds will generally be calm to
light and VRB through the early morning hours east of the mountains.
KAVL will see light S/SE winds through daybreak. LLWS will develop
across the terminals, lingering through ~15Z east of the mountains
and ~18Z at KAVL. Winds east of the mountains will pick up out of
the S/SW later this morning into this afternoon. Winds at KAVL will
turn more S/SW late this morning into this afternoon, becoming NW
this evening behind the cold front. Wind speeds will gradually
increase across the terminals later this morning into this afternoon
becoming breezy. VFR is expected to continue through mid-
morning/early afternoon before cigs gradually lower to MVFR to IFR
levels from west to east ahead of a cold front. SHRA chances will
also gradually increase from west to east ahead of and along the
front this afternoon/evening. Have PROB30s to account for onset of
precip and restrictions with prevailing SHRA by the late
afternoon/early evening hours. Drier conditions will move in behind
the front from west to east this evening into tonight. Cigs will
gradually improve behind the front as well this evening, returning
to VFR levels. Wind gusts will gradually taper off throughout Friday
evening. Patchy fog may develop late Friday night but confidence on
this is low at this time.

Outlook: Drier conditions linger into early next week but periodic
restrictions may occur through at least the weekend. Confidence on
cig and vsby restrictions is low at this time.

&&

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

&&

$$

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