Greenwood, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

349
FXUS62 KGSP 142158
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
558 PM EDT Wed May 14 2025

.SYNOPSIS...
Low pressure will move slowly northeast to the Mid-
Atlantic Coast tonight then off the coast on Thursday. Drier
high pressure moves over our area Thursday with a weak
cold front moving south across our area over the weekend then
the front becomes stationary.  Above normal temperatures will
continue through the weekend and into early next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 5:45 PM EDT Wednesday: Convective activity/coverage has dimin-
ished over the past couple of hrs with most of our CWA currently free
of showers except for sct activity over the I-77 Corridor. Even that
activity is all showers and currently no lightning. Nonetheless, with
decent amounts of sfc-based instability and 30+ kts of deeper-layer
shear still present over our area, we can expect more isolated to sct
showers and thunderstorms well into the evening. Any deeper and well-
maintained updrafts will have the potential to produce severe weather.
Large hail and locally damaging straight-line winds will be the main
threats with any stronger storms. Activity may linger well into the
evening, but coverage is not expected to increase appreciably.

Otherwise, fcst confidence wanes tonight as guidance is split as to
whether an upstream convective complex can initiate over eastern Ken-
tucky and Tennessee as a weak impulse slides across the area within
the NW flow regime. Should convection become organized, a complex of
storms may make a run at the mountains after midnight and into the
early morning hrs. The most aggressive CAMs try to maintain convec-
tion into the North Carolina foothills and perhaps even Piedmont.
Most recent runs of the HRRR, on the other hand, have a much more
muted response and a generally quiet evening. A conditional threat
for severe weather will continue overnight should any upstream con-
vection materialize and move into the area. The fcst should finally
quiet down tomorrow as the trof axis gets kicked out of the area and
heights rise as a tall shortwave ridge slides into the Appalachians.
A few upstream showers or storms may make a run at the mountains, but
once again a very uncertain fcst right now. Otherwise, temperatures
continue to march up tomorrow with highs in the low to mid 80s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 130 PM Wednesday, key messages:

1. Capping Friday still looks to inhibit convection over the CWA in
what otherwise would be a very concerning environment for severe
weather.

2. Organized convection however appears likely to develop in the
lower OH or TN valleys Friday, and could track into or across the
Appalachians at some point between Friday evening and Saturday
morning.

3. Muggy Friday with temperatures about 10 above normal.  A little
cooler and less humid Saturday but still above normal.

Upper ridge axis will shift east across the CWA Thursday night into
Friday, with slight height falls then occurring aloft as shortwave
swings through the mid-Mississippi Valley, surrounding an occluding
cyclone near Minnesota. The warm front associated with the ridge
looks to have brought an elevated mixed layer over the area, making
convection and precip in general highly unlikely Thursday night even
as WAA continues aloft. The EML still looks to remain in place
through Friday, providing 100 J/kg or more of CIN east of the
mountains. Recent NAM runs depict the CIN diminishing in parts of
the Piedmont, although that seems to come as a result of
exceptionally high dewpoints in the lower to mid 70s. Values are
more likely to remain at or below 70 so we will continue to assume
the cap prevails. SBCAPE is about as high as one ever sees on models
in this area, with prog soundings showing as much as 5000 J/kg owing
to the deep layer with near dry-adiabatic rates--but with the strong
CIN resulting in no corresponding QPF response.

Similarly unstable profiles are seen west of the Appalachians
Friday.  Via the tight height gradient there and across our CWA as
well, 0-6km shear is likely to exceed 50 kt. CAMs appear to show
supercells developing in Arkansas or western KY/TN Friday morning
and tracking east thru the day; HRW-FV3 for one shows cells reaching
the Appalachians north of our area in the afternoon, and the FV3-
based GFS shows streaks of precip response suggestive of a similar
evolution. CIN is comparatively weak in our mountains, and such
developments prompt chance PoPs in those zones Friday afternoon,
even though in-situ development still is unlikely.

The Midwest system will drive a cold front east of the MS River by
Friday evening; as it moves southeastward it will encounter large
MUCAPE, still with very strong flow aloft. Most guidance suggests
widespread convection developing there overnight, if not upscale
growth into an MCS. The best organized activity probably will track
to our north, but there remains a good chance that at least decaying
convection will reach the NC mountains early Saturday morning. Shear
will be strong and severe wx can`t be ruled out, but instability
will be the limiting factor. Given the timing, cold pool or outflow
from said activity generally is shown to make diurnal convection
unlikely over the mountains Saturday; it could however set up
differential heating and serve to enhance initiation Saturday
afternoon, when shear will remain favorable for damaging wind/hail
threat. Confidence remains low due to the difficulty in predicting
the extent of morning convection.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM Wed: Cold front associated with the Midwest system
should push through the area Saturday night. Heights rise in the
lower to mid MS Valley Sunday and the front is shown to stall and
reactivate. The major global models and ensembles have trended such
that the front appears more likely to settle through the area and
keep us stable and largely precip-free Sunday and possibly even
Monday, particularly east of the mountains. Temperatures will trend
cooler although any post-frontal cooling could be offset by
downslope NW low-level flow, so temps mostly remain a little above
normal. However, deep convection could develop along the warm front
over KY/TN and the flow will be oriented such that we may be in the
track of any MCS. Upper low east of the Rockies should lead to the
next cyclone developing circa Tuesday; as the upper ridge shifts
east in advance of those features, we generally look to be in a more
favorable environment for convection Tuesday into Tuesday night,
with warm front shifting north and/or with cold front approaching
from the west.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Morning stratus has since lifted and
scattered with most ceiling restrictions coming to an end, although
a brief period or two of MVFR cannot be ruled out at any given
terminal. Isolated to widely scattered showers and thunderstorms are
expected this afternoon into the evening, but where these may form
is uncertain. PROB30 groups have been maintained at all TAF sites
accordingly, but will need updating once storms develop and tracks
become more certain. The forecast becomes murky overnight as another
round of showers and storms may drop into the area from the
northwest. Confidence as to whether this actually occurs remains low
and will preclude mention in the TAF at this time. There will also
be the potential for another round of low stratus, which has been
advertised as MVFR for now. Should storms move through the area, fog
and stratus issues would be less likely. Should fog and low stratus
develop, some terminals may see restrictions worse than currently
advertised, potentially as low as IFR/LIFR. Any fog/stratus should
lift/mix out through the morning hours tomorrow with a return to VFR.

Outlook: In general, a summertime pattern is expected through
the end of the week with diurnally driven convective storms each
day. In addition, fog and low stratus will be possible each morning,
primarily in the mtn valleys and in areas that receive appreciable
rainfall the previous day.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT/TW
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...JPT/TW