Central, South Carolina Weather Forecast Discussion

355
FXUS62 KGSP 271047
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
647 AM EDT Sat Sep 27 2025
.SYNOPSIS...
A moist cold front will stall along the Carolina Coast this weekend,
keeping unsettled weather around. A tropical system will likely impact
the area early next week but confidence remains low at this time with
regards to specific impacts. High temperatures will remain near normal
through the weekend before dropping below normal early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 652 AM EDT Saturday: Numerous/widespread showers with a few
embedded thunderstorms continue to lift northward over the eastern
third of the fcst area, especially metro CLT and the I-77 corridor
at this early hour, in a plume of high sub-tropical moisture on the
east side of an upper low dropping thru the mid-TN Valley into nrn
AL/nw GA. The main concern continues to be the rainfall with fairly
slow movement overall and now some training taking place. Up until
now, however, the movement has been just enough to keep places
from getting enough rain to cause any flooding. It helps that we
started out really dry with low stream flows, as well. Cannot rule
out some flooding, particularly over the NW Piedmont that had an
earlier round of heavy rain in the late evening, but confidence for
a flood watch is not there. This was all going more or less to plan,
as a shot of upper divergence in the right entrance region of a
jet streak and good DPVA lifts northward through the early morning
hours. This warrants the continuation of a high precip prob over
the eastern half, but starting to drop off after 12Z. Temps will
once again flirt with record high minimums.
As the upper low pivots east into northwest GA this morning,
the main short wave is expected to lift northeast and out of the
fcst area by mid-morning and slightly drier air may work in from
the southwest. This should bring on a bit of a lull in the precip
coverage from mid-morning thru early afternoon, but destabilization
that results from the trof axis moving overhead should help to
kick off the next round of convection by 18Z across mainly the
mtns. Precip probs drop off accordingly, but ramp right back up
thru the diurnal maximum. The afternoon convection should expand
and move outside the mtns thru the early evening hours as the trof
axis shifts eastward. There will remain some concern for flooding
across the foothills and northwest Piedmont through that time,
given the overnight rain that has those parts more primed for better
runoff. As for temps, expect highs to be right around normal. For
tonight, the upper low center continues to pull northward but
leaves the trof axis behind across the western Carolinas. Not
much in the way of mid/upper forcing, however, and the conveyor
belt feature on the east side of the low/trof weakens and moves
to our east. Thus, once we lose daytime heating, there should be
a gradual die-off to the showers and storms, then a quiet night
after 06Z or thereabouts. Temps will remain seasonally mild,
but not record-breaking like the past few nights.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 1:15 AM EDT Saturday: The short-term forecast picks up at 12z on
Sunday with what`s left of a southern-stream upper trof lifting north-
ward and getting cut off from the mean flow. By early Monday, whatever
is left of this low will get absorbed by broad upper ridging that spreads
over the eastern CONUS. At the sfc, some degree of mid-level drying is
expected on Sunday with the better upper forcing weakening and shifting
NE of our area. Nonetheless, a fair amount of low-level moisture will
linger over our area thru Sunday. Thus, we can expect any convective
coverage to be more isolated to scattered for most of our fcst area,
with little (if any) activity over the SW Upstate and NE GA. Brief,
heavy rainfall remains possible along with a few stronger storms, but
the severe potential looks very low. On Monday, what is currently PTC 9
will be approaching the SE Coast while Hurricane Humberto is expected to
remain further offshore. By the end of the period early Tuesday, most of
the latest model guidance has the center of PTC 9 still sitting just off
the SE Coast with deep-layer wrap-around moisture over our fcst area.
At this time, the main potential hazards thru early Tuesday will be
excessive rainfall and some gusty winds. WPC`s Day 4 ERO currently has
most of our CWA in a Marginal Risk for excessive rainfall thru early
Tuesday with our eastern zones likely getting the most precip overall.
Confidence wrt specific precip amounts should improve over the next
few days. Stay tuned.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 1:10 AM EDT Saturday: The extended forecast picks up at 12z on
Tuesday with Hurricane Humberto expected to be well off the SE Coast,
while what is currently PTC 9 is fcst to be just off the SE Coast and
likely either Tropical Storm or Hurricane strength by early Tuesday.
Over the next 24 to 48 hrs, it remains unclear whether this tropical
system will actually move inland over the Carolinas and/or Georgia,
or whether robust sfc high pressure diving south from Canada will
push the system back offshore. The majority of the latest long-range
guidance now appears to move the tropical system back out over the
Atlantic on Wednesday and Thursday. The operational ECMWF still tries
to move the system inland over southern Georgia by late week, but this
scenario doesn`t appear to be as likely. Regardless, if either of the
above scenarios occurs, we can expect some amount of widespread rainfall
and gusty winds across our fcst area on Tues and Wed with potentially
drier conditions for Thurs and Fri. It`s still too early to place much
confidence in specific rainfall amounts and/or how strong our winds will
be, but it`s looking like wind speeds should remain below Tropical Storm
strength across our CWA. Regardless, this system will need to be watched
closely over the next few days. Stay tuned.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Looks grim through mid-morning across the
region, with widespread restrictions that will be variable in time
and space. Generally speaking, ceilings could range anywhere from
VFR to LIFR at all terminals thru mid-morning. The bulk of the
rain should fall in the I-77 corridor and KCLT, but a shower or
thunderstorm could develop at any time and at any location thru
mid-morning as an upper wave moves thru, providing a favorable
environment. Wind will be light/variable. Once the wave passes,
expect a lull from mid-morning thru early afternoon. The lowest
cloud deck should mix out and leave behind an MVFR ceiling that also
may lift and scatter to VFR. The next round of storms will develop
over the mtns around 18Z and then will expand outside of the mtns
thru early evening. This will be handled with TEMPOs. Wind will
be mostly S to SW thru that period. Once the rain moves out, the
overnight will be quiet, but with more restrictions developing. Will
indicate MVFR/IFR stratus in the pre-dawn hours at all terminals
for now, with more details added later.
Outlook: Mainly diurnal shower and thunderstorm chances, as well
as associated restrictions, linger into Sunday thanks to a stalled
front along the Carolina coast. Fog and low stratus are possible
each morning, mainly in the mountain valleys and any locations that
received heavy rainfall the night prior. A tropical system could
bring widespread restrictions and rain to at least a part of the
area early next week, but confidence remains very low at this time.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JPT
NEAR TERM...PM
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...PM

NWS GSP Office Area Forecast Discussion