914
FXUS62 KGSP 060008
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
708 PM EST Wed Feb 5 2025

.SYNOPSIS...
Unsettled weather and warmer temperatures return on Thursday
and linger into the weekend. Another cooldown and more
precipitation will be in store for the early part of next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 545 PM: Starting to see a few small showers pop up on radar
from around Lake Hartwell to near Newberry, within area of small
CAPE. Dewpoint depressions are relatively large to start out, but
returns appear low enough to the ground to accelerate the onset
of PoP in that area this evening. Still think precip mainly will
be confined to this area and the SW NC and NE GA mountains near
warm front, basically the "wedge front" for the low-impact CAD or
lookalike event which developed earlier today. As moisture deepens
and LLJ strengthens late evening to early Thu morning, think precip
will develop over more of the area as previously fcst. Adjusted
T/Td/Sky trends for the next few hrs but think that aspect of the
fcst is mainly on track after about midnight.

For the next 24 hours, there is an expectation that more of the
forecast might not go as planned by some of the earlier model
guidance. The NBM and the CAMs remain somewhat at odds with the
coverage of precip developing mainly across the area east of the
mtns. There is good agreement where the deeper forcing lies to the
south of an inverted trof on the other side of the mtns in that
much of the guidance suggests showers moving WSW/ENE and scraping
along the TN/NC border overnight and Thursday. Can`t really argue
with this, especially Thursday as the actual cold front lays out
and sags across eastern KY/middle TN. Precip probs will ramp up
to likely along the TN border late tonight and stay there through
the morning. Some elevated CAPE suggests the potential for some
thunderstorms on the west side of the mtns. Meanwhile, east of the
mtns, confidence is poor. A surge of low level moisture from the
SW is still possible...note the cloudiness over AL moving into
western GA this afternoon...especially if low level isentropic
upglide develops as shown in the guidance. Expect the low clouds
to finally fill in and expand with the low level moisture/upglide
arrival. Will this be enough to develop as much precip coverage
as shown in the NBM? There are doubts, especially with the wedge
not having really developed today. Have pushed the forecast in
the direction of lower prob to account for this, such that much
of the precip chances retreat to the mountains and foothills
first thing tomorrow and the bulk of the Piedmont/Upstate stays
dry. That makes the high temp forecast tricky again. Assuming we
get the low overcast by daybreak, that typically would result in
a delay in warmup until mid-afternoon over the NC Foothills/NW
Piedmont, keeping the high temps down. Will undercut the NBM in
those areas by a few degrees, but this fcst could easily be +/-
5 or 10 degrees off, not to mention a possible tight temp gradient
in the afternoon not depicted in the forecast.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 200 PM EST Wednesday: Broad quasi-zonal flow aloft and
anomalously high heights will set the stage for the forecast period
as a strong deep layer low traverses across the eastern Canada. The
attendant trailing frontal boundary will gradually move into the
CFWA from the northwest and stall over the area on Friday as the
boundary becomes parallel to the prevailing westerlies and doesn`t
have anything to drive the boundary further south. As a result,
locally enhanced convergence, enough shallow low-level moisture,
and the existence of upper dynamics may be able to kickoff scattered
showers by Friday afternoon/evening, mainly across the southern half
of the CFWA, on the moist of the boundary. Can`t rule out a rumble
of thunder with a couple hundred J/kg of elevated instability,
but that`s about the extent of the activity as coverage will
be scattered in nature. Model guidance favor a pivot with the
stalled boundary that would help provide a slight drift northwest
by Friday night as the northern stream jet slowly lifts north,
which would set the stage for more shower develop, especially over
NC mountains and locations along and north of I-40 by Saturday
morning. There are differences in the locations of the boundary, so
this will decide ultimately where the shower development occurs as
some of the guidance initially has the boundary south of the CFWA
Friday afternoon/evening and lifts north into the CFWA by Friday
night. With this type of uncertainty, slight chance and chance
PoPs will extend across much of the region Friday into Saturday.

A strong shortwave trough is shown pushing from the Northwest
Pacific Friday through the Northern Plains by Saturday. In this set
up, surface cyclogenesis will be underway and allow for a surface
low to develop along the stalled frontal boundary that`s from the
Southeast/Deep South/Southern Plains and lift into the Midwest/OH
Valley by the end of the forecast period. In this case, the stalled
boundary over the area could undergo warm frontal activation and
shift to the north, setting the CFWA underneath a rather broad warm
sector if the warm front shifts quickly to the north. Either way,
locations in the vicinity of the warm frontal activation could
receive an additional round of showers. We will be experiencing a
warm and relatively active set up for the short-term, which looks
to extend into the beginning portions of the medium range forecast
as well. Temperatures Thursday night will run extremely warm with
values 20-25 degrees above normal with dewpoints in the mid to
upper 50s, extensive cloud cover, and lingering precip. Afternoon
highs Friday will rise substantially in locations south of the
aforementioned boundary as dewpoints remain elevated and very warm
thicknesses remain in place as values rise to 15-20 degrees above
normal. Could be a few notches lower in locations such as the higher
elevations and north of I-40, depending on where the boundary sets
up by peak heating. Friday night lows will be dependent on how far
south the boundary resides as locations north of it will run 10-15
degrees above normal, while locations south of the boundary will run
15-20 degrees above normal. A tight temperature gradient may exist
for Saturday afternoon highs as the warm frontal activation slowly
lifts north, potentially keeping clouds and precip in the northern
zones of the CFWA, while better WAA filters in south of the boundary
leading to afternoon highs 10-15+ degrees above normal, while
northern locations may only get up to 5-10 degrees above normal.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 245 PM EST Wednesday: The aforementioned surface low is
expected to quickly push into the northeastern CONUS and offshore by
the start of next week and will bring another trailing cold front
into the region Sunday. With the better forcing well offshore
by the time the front enters the region, not much activity may
spark from the boundary. Quasi-zonal flow aloft still in place
will allow for the boundary to stall over or in the vicinity of
the CFWA late Sunday into Monday. Model guidance keep an active
and more progressive pattern over the area as the jet stream
stretching from the Southern Plains through the northeastern CONUS
activates the stalled boundary and provides continuous chance to
likely PoPs through the rest of the period as the front remains
draped across the Southeast and Deep South and multiple waves
develop and ride along the boundary. Model guidance are in decent
agreement considering the fact that this is beyond D4, but timing
uncertainties exist, so kept ongoing PoPs as a result despite some
dry slots from time to time during the period. Temperatures Sunday
will be the last very warm day of the seven day forecast as the
CFWA enters a warm sector, ahead of the cold front with afternoon
highs up to 20 degrees above normal. With extensive cloud cover,
elevated PoPs and some form of a wedge configuration will bring in
colder temperatures starting next Monday through D7 as values will
be near to even slightly below normal as a result for afternoon
highs and 5-10 degrees above normal for overnight lows.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: A small amount of instability invof a warm
front is driving a few SHRA and even isolated TSRA at issuance
time, near KAND and south of KGSP/KGMU. TSRA appear too isolated
to mention at this time, but with forcing elements persisting,
will start with VCSH at the SC sites. Chance will peak overnight
as low level jet strengthens, resulting in TEMPO at KAND and PROB30
at KGSP/KGMU/KHKY, and VCSH elsewhere. SHRA may be associated with
MVFR vsby. Otherwise, low stratus within sfc wedge has expanded
west to KCLT but does not appear likely to lower below MVFR until
after midnight, by which time it is expected to expand over the
other terminals. KAVL will see southerly upslope clouds develop and
also go MVFR. Can`t rule out that precip will accelerate lowering
of cigs, but those are likely to fall to IFR by around daybreak as
it is. Winds will remain ENE most of tonight except at KAVL which
will remain SE; wedge setup will weaken to the point winds turn SW
by then. Clouds are likely to scatter late morning to midday and
bases will lift to MVFR if not VFR level for the afternoon. Low
clouds could redevelop Thu night with moist low levels and slight
warm upglide continuing prior to weak cold fropa early Fri morning.


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...CAC/Wimberley
NEAR TERM...PM/Wimberley
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...Wimberley