Spartanburg, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

382
FXUS62 KGSP 301141
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
641 AM EST Thu Jan 30 2025

.SYNOPSIS...
High pressure builds in today with increasing clouds, as low
pressure develops over the southern Plains. An associated cold front
will cross the area Friday, bringing widespread showers across the
area. Drier and warmer weather expected this weekend into the early
part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 636 AM EST Thursday: The IR satellite imagery shows bands of
orographic cirrus lingering over the NC foothills/wrn Piedmont,
out ahead of the approaching cirrus shield associated with the
right entrance region of an upper jet streaming overhead. The low
clouds were messing up the low temps, which are quite variable
across the region at daybreak.

The latest model guidance shows good continuity with what we`ve
been expecting for today and tonight in terms of the evolution of
the upper low forecast to move across the srn/central Plains and
the development of an effective warm front across the TN Valley
to Mid-Atlantic regions. A flat mid/upper ridge axis should move
overhead today and push the sfc high from the central Appalachians
this morning to a position off Cape Hatteras this evening. This
is expected to bring the low level flow around to SE and S as the
day progresses, starting the process of increasing the warm/moist
advection over the western Carolinas. We might expect another
relatively warm day if it wasn`t for the high clouds this morning
giving way to a thickening altocu cloud deck as mid-level moist
isentropic ascent moves overhead this afternoon. Can`t rule out
some light rain over the NC mountains and north of I-40 as the
eastern extent of the developing warm front scrapes past along the
TN/NC border. However, the extent of the cloudiness should limit
our high temps to roughly ten degrees less than yesterday, though
still more than five degrees above normal. The trend of the guidance
has been slightly downward and that seems reasonable. Tonight on
the whole looks relatively dry across most of the fcst area with
the main precip band associated with a warm conveyor belt ahead
of the cold front remaining to the west of the fcst area through
daybreak Friday, while the precip associated with the isentropic
lift and warm advection along the warm front lurks just to our
north. A precip prob gradient will be maintained along the TN/NC
border and the nrn edge of our fcst area. All the low level warm
advection should keep the overnight temps seasonally mild and on
the order of ten degrees above normal.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 200 AM EST Thursday: Mid/upper-level closed low will
translate into an open wave as it lifts into the OH Valley through
the northeastern CONUS Friday into Saturday. The attendant cold
front will be knocking on our door by daybreak Friday as the CFWA
is entrenched underneath a broad warm sector as the parent low
rides underneath the mid/upper low lifting further north/east. WAA
filtering in with anomalously high PWAT values for late January
and good forcing with a narrow band of DPVA lining up with the
trailing front and rapid height falls, expect for rain chances
to increase just ahead and along the cold front. The front and
associated precip is expected to shift from west to east across
the CFWA from daybreak Friday in the Smokies to crossing the
foothills and Piedmont zones around lunchtime and pushing east of
the area by around sunset Friday. Two of the three ingredients for
severe weather is in place, which is very stout deep layer shear
(0-6 km bulk shear over 80 kts) and available moisture (PWAT:
~1.25"-1.50"). The ingredient that`s lacking based on guidance
is SBCAPE, which is basically 0 J/kg. There are some instances
of ~100 J/kg of MUCAPE and may create pockets of moderate to
heavy rainfall rates, but the lines of scattered showers will be
progressive as the front moves across the area at a relatively
fast pace, so not expecting any hydro threat. QPF amounts have
actually lowered in recent trends with most locations receiving
~0.25"-0.50", with locally high amounts possible in areas that
receive heavier rainfall rates and the favorable facing slopes in
the southwest NC mountains. With the CFWA placed under the warm
sector of the low pressure system, expect for afternoon highs to
be 5-10 degrees above normal before the rainfall moves in. Places
south/east of I-85 could exceed 10 degrees above normal as these
locations will have more time to warm up before the onset of precip.

Dry air entrainment will commence behind the front as the flow
toggles to a northerly component by Saturday and weak high pressure
moves in behind the fropa. The flow aloft flattens out and heights
recover in the process, which will keep temperatures on the warmer
side of normal despite the cold fropa as warm thicknesses remain
in place through the end of the forecast period. Overnight lows
both Friday and Saturday night will be 4-8 degrees above normal,
while afternoon highs on Saturday run 5-10 degrees above normal
with mostly sunny skies.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 300 AM EST Thursday: Flow aloft remains quasi-zonal through
much of the forecast period, while an active northern stream remains
too far north for much activity in our neck of the woods. Guidance
diverge by the end of the forecast period with the GFS trying to
send a moist front into the region by D7, while the ECMWF/CMC hold
off until after the medium range ends. With very warm thicknesses
in place, expect for temperatures to remain on a very warm trend
with the exception of Sunday where temperatures may drop a few
ticks thanks to a reinforcing surface high sliding across the
Northeast. However, temperatures through midweek will be toasty
for early February with values 10-15 degrees above normal.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Expect VFR conditions at all terminals thru
the TAF period. Extensive high clouds are expected this morning,
either from orographic cirrus over the foothills/wrn Piedmont, or
the cirrus shield invading from the west. This will be followed by
mid-level clouds thickening in the late morning as moisture spreads
across the region. Some precip aloft was noted on radars to the
west, so a few sprinkles are possible today, but no restrictions
are expected. That leaves us with another wind forecast. The wind
direction is expected to go SE and S during the mid-to late-morning
as a warm frontal feature develops. The timing of this wind shift
is uncertain. Once the warm front lifts northward, Wind should
stay S to SE, generally from 18Z onward. A cold front will not
reach KCLT before the end of the period. Out ahead of the front,
a strong southerly low level flow could result in low level wind
shear around daybreak to late morning.

Outlook: Restrictions will return Friday as a cold front moves
across the region. VFR conditions are expected to return on
Saturday and continue through Monday. Guidance is uncertain for
Tuesday and Wednesday as a cold front may move in from the NW.

&&

.FIRE WEATHER...
Lighter winds and higher RH values (30%-35%) today will help ease
favorable fire weather conditions. A cold front will bring rain
across the area of Friday and should help eliminate any additional
threat for fires to develop.

&&

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

&&

$$

SYNOPSIS...CAC
NEAR TERM...PM
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...PM
FIRE WEATHER...