457
FXUS62 KGSP 080243
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
943 PM EST Fri Feb 7 2025

.SYNOPSIS...
Well above normal temperatures will generally continue through the
weekend. A back door cold front will push through the area late
Sunday, ushering in much cooler temperatures Monday through Tuesday.
Unsettled weather conditions will likely persist through most of
next week, as a front stalls over the region.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 930 PM, key messages and latest updates:

1. Shower activity north of the stationary front has diminished
in coverage, but a few showers could redevelop generally near
the NC/SC border thru 1 AM or so. Precip chances increase late,
particularly in GA/SC and SW NC, as isentropic lift strengthens
over the front. PoPs adjusted per latest thinking.

2. Widespread cloud cover expected to develop by daybreak and linger
most of Saturday. Clouds not likely to fill in quickly overnight,
so reduced sky cover thru the wee hours of the morning.

3. Patchy fog may develop where it rained during the evening,
but this fog is expected to be short-lived, as drier air works in
from the north later tonight.

A frontal boundary remains stalled to our south as the center
of high pressure moves into the Mid Atlantic and builds down the
east coast in a cold air damming configuration. Low level moisture
increases aloft toward morning; clouds will remain transient through
the middle of the night and then look to expand across the Piedmont
up to around the Blue Ridge Escarpment.  The overall forcing is weak
with the low level winds on the light side and more southwesterly
winds limiting any upslope flow so overall precip coverage should
remain isolated most of the night, increasing toward dawn but still
not enough for more than scattered wording. QPF still no more than
a tenth or so. Lows will be around 15 degrees above normal keeping
precip as liquid rain.

The frontal boundary lifts northward Saturday but weakens as it
tries to scour the damming wedge. The wedge isn`t very strong with
little in the way of precip to lock it in place, but presently
we expect clouds to linger across the area most of the day with
spotty light rain, especially during the morning, along and near the
Upper Savannah River Valley. Temps will be tricky. The model blend
wants to go on the warm side, while the guidance with the strongest
damming is quite cool. Have blended the two as a compromise. This
gives highs anywhere from 5 degrees above normal where the wedge
holds on the longest to around 15 degrees above normal where it
can erode and the lower mountain valleys along the TN border where
the damming air mass usually has less influence. Of course, the
strength of the high and potential erosion will determine where
highs actually end up.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 215 PM EST Friday: Highly zonal flow will persist thru
the short term across the eastern CONUS, while an upper trough
begins to dig across the West. At the sfc, a very warm air mass
for this time of year will be in place ahead of an approaching cold
front. Deep-layer westerly flow should limit rain chances to mainly
the TN border areas Saturday night into Sunday, but a few stray
showers or sprinkles cannot be ruled out elsewhere. Lows Saturday
night will be about 20-25 degrees above normal. The cold front will
slip thru the area during the day Sunday, which will help keep temps
only a few degrees above normal along the TN border, but downslope
flow will lead to temps 15-20 degrees above normal elsewhere. The
GSP climate site will have chance at reaching the daily record high.

The front lays over the area Sunday night and stalls out over the
Deep South Monday. A strong 1030-1035 mb sfc high will build into
the Ohio Valley and the Mid-Atlantic. This should set up classic
CAD, with increasing cloud cover and NE flow bringing temps back
down closer to where they should be for mid-February. Moisture and
isentropic lift looks to be limited to the southern part of the
forecast area, so only spotty slight chc to low-end chc PoPs are
expected. The CAD will be strong enough that spotty light freezing
rain may develop in the highest elevations of the Northern Mountains
during the day Monday. But not expecting any major impacts.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 230 PM EST Friday: A very unsettled wx pattern on tap for
the medium range, as a series of waves ride along a persistent
baroclinic zone draped across the Southeast. The upper pattern
will amplify into a western-trough/eastern-ridge, with individual
shortwaves ejecting out of the trough and tracking east thru the
region. The medium range guidance is in good agreement a round of
precip Tuesday into Tuesday night. Classic CAD will have diabatic
enhancement to bring temps down into the 30s to lower 40s across the
forecast area. Pockets of sub-freezing temps near the eastern Blue
Ridge escarpment may result in some freezing rain or even snow/sleet
in the Northern Mountains. But confidence in the thermal profiles
is low. For the most part, it will be a cold, rainy day Tuesday,
with highs close to 10 degrees below normal.

The models start to diverge/get out of sync with the next waves
in the series. The GFS has the period of heaviest precip Tuesday
night, while the ECMWF and Canadian are more Wednesday into
Wednesday night. Strong forcing and a good moisture tap out of
the Gulf may result in locally heavy rainfall, especially in the
western/southwestern-facing slopes of the NC mountains. There is
less confidence in QPF further east.

One final wave of energy is expected to kick the upper trough out
and cross the eastern CONUS Thursday, bringing a possile third
round of rain, with a cold front crossing the forecast area. By
this point, CAD is expected to weaken enough for all precip to be
rain, with temps warming slightly. But cool, cloudy, rainy weather
is expected to continue until the cold front pushes thru. Upper
ridging builds into the eastern CONUS by next Friday, with another
strong sfc high pushing into the Great Lakes and Mid-Atlantic. Drier
conditions are expected to return, but possible dry CAD may keep
temps near normal.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Warm upglide, already underway in the
midlevels, is tapping into some shallow elevated instability to
produce -SHRA near all sites except KAND, which prompted VCSH
inclusion. TEMPO for greater confidence in associated brief vsby
restrictions at KCLT/KGSP/KGMU. Can`t rule out redevelopment of
light precip overnight but chance below VCSH threshold everywhere
except KAND which will be the first to see lower level upglide
develop within marginal cold-air damming regime. MVFR cloud layer
likely to develop by around daybreak at KCLT and the SC sites, which
will persist through most of the day. IFR likely to be kept at bay
by dry PBL; if precip develops more than currently anticipated
overnight, IFR may develop by morning. Winds will turn NE this
evening where not already so, although will be generally light
overnight. These should turn southerly at KAVL before daybreak
and by midday elsewhere. Isolated instances of LLWS are possible
after 00z Sun but too unlikely to mention at KCLT this issuance.

Outlook: Frontal boundary wavering over the region will offer
periodic chances for restrictions from Saturday night through most
of next week. Periodic showers are also possible in that timeframe,
with best overall chances Tuesday thru Thursday.

&&

.CLIMATE...
RECORDS FOR 02-09

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      71 1957      7 1895     54 1921     -2 1895
   KCLT      77 1994     31 1933     60 1994      6 1895
                            1895
   KGSP      76 1994     31 1933     58 1937      9 1995
                            1905

&&

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

&&

$$

SYNOPSIS...JDL
NEAR TERM...RWH/Wimberley
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...Wimberley
CLIMATE...GSP