Sharon, South Carolina Weather Forecast Discussion

166
FXUS62 KGSP 021736
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
136 PM EDT Thu Oct 2 2025
.SYNOPSIS...
Dry high pressure ridging down from the northeast will control our
weather through Friday, bringing cooler than normal temperatures. As
the center of high pressure moves offshore, temperatures return to
near normal for the weekend and early next week.  Moisture increases
Sunday through early next week ahead of an approaching cold front
which arrives in mid week.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1142 AM Thursday: Quiet weather continues through the near
term as broad upper ridging settles from the Ohio Valley through the
southeast states. Surface high pressure will also continue to drop
south along the east coast with a continued dry and cool airmass
across much of the region. A few wind gusts will continue this
afternoon within the well mixed boundary layer with winds subsiding
overnight. A few instances of patchy fog will be possible early
Friday morning as well, but mainly limited to most favored mountain
valleys and cool drainages/near bodies of water. Slight modification
of the airmass begins Friday, but temperatures are only expected to
be a degree or so warmer compared to today.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 1230 PM Thu: Dry cold-air damming will remain the story into
the weekend. Although the high will shift far enough south and weaken
such that the conditions for classical CAD are not met by early
Saturday, there will be no appreciable erosion mechanism aside from
airmass modification.
Low-level flow will veer to a slightly more easterly direction early
in the period, more supportive of moist upglide over the surface
wedge. Some cirrus likely will spread north over the CWA from
convection along the stalled front in the Gulf.  However, guidance
has slowed development of cloud cover Saturday, now not expecting low
clouds to form until that night as flow veers more decidedly SE and
RH increases in the low levels.  Both those changes are a consequence
of upper ridge axis and damming high shifting off the East Coast,
allowing moisture flux from the aforementioned frontal zone--possibly
enhanced by a developing sfc wave along it.  Cloud cover will be
maintained Sunday, but models have slightly slowed the onset of
precip in the moisture plume such that low (20%) PoPs only reach our
southern zones Sunday afternoon.
Temps will warm a few degrees Saturday compared to Friday,
particularly with skies looking clearer than before. Maxes end up a
little above climo, but still mild and in the 70s in most spots. With
developing cloud cover Sat night, mins will be as much as 10 above
normal Sunday morning. Cloud cover Sunday should keep maxes similar
if not slightly cooler.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 110 PM Thu: Moisture flux on the southwest flank of the sfc
high will maintain abundant cloud cover Sunday night and allow precip
chances to expand north to the Blue Ridge Escarpment by daybreak
Monday. PoPs now reach a mentionable threshold (20-30%) in all zones
by Monday afternoon and persist Monday night. As noted previously,
the lack of a clear CAD erosion mechanism over the weekend suggests
that the development of any precip likely would result in diabatic
enhancement to the remaining wedge, and thus potential for a busted
temp forecast (both lower maxes and higher mins). In that sense, not
much change to expectations for early next week. NBM max temps have
trended a little cooler Monday and Tuesday, possibly reflecting more
members resolving the diabatic cooling.
On the flip side, there still are some ensemble members which remain
dry through this time, and drier models should translate to warmer
temps. Precip probably would be very light, but there remains some
support for a compact sfc low developing within the moisture plume,
enhancing the low level gradient and resulting in appreciably higher
precip amounts. All this to say confidence remains low and this is
partly why PoPs early next week have not increased much since
yesterday`s forecast.
Meanwhile, early next week continental high pressure will expand out
of the northern Plains and push a cold front into the eastern US.
Some guidance indicates the subtropical moisture plume beginning to
interact with the front or its associated trough as soon as Monday
night, but more likely Tuesday night or Wednesday. Potential for CAD
(by then of the in-situ variety) is similar Tuesday compared to
Monday, with 20-30% PoPs once again and a flat trend in temps. Those
models depicting the front arriving Wednesday seem to erode the wedge
and allow slightly warmer temps at that time, along with higher
chance-range (40-50%) PoPs. SBCAPE generally is shown to develop
ahead of the front, so all areas also receive a mention of thunder,
but it is not yet clear whether the instability will overlap with
enough shear to produce severe weather threat.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions will prevail at most terminals
through the TAF period. Easterly winds lifting along the Blue Ridge
escapement continue to foster the development of low stratus across
the mountains with lingering MVFR at KAVL. Satellite trends
indicate lessening coverage of clouds with scattering expected over
the next hour or so with a return to VFR. Heading into tonight,
patchy fog cannot be ruled out at any given terminal, but overall
coverage should remain isolated and precludes mention in the TAF at
this time. A few wind gusts will remain possible through this
afternoon and a couple gusts cannot be discounted tomorrow, although
they shouldn`t be as prevalent with surface high pressure dropping
closer to the area from the north.
Outlook: Dry high pressure is expected to remain over the region
into the weekend. Expect VFR conditions to prevail with the
exception of patchy morning fog and low stratus in the mountain
valleys each day. Scattered showers may return late Sunday into
Monday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...TW
SHORT TERM...JCW
LONG TERM...JCW
AVIATION...TW

NWS GSP Office Area Forecast Discussion