Spear, North Carolina Weather Forecast Discussion

216
FXUS62 KGSP 271757
AFDGSP
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
157 PM EDT Sat Sep 27 2025
.SYNOPSIS...
A stalled front will remain along the Carolina Coast through
the rest of the weekend, while an area of high pressure builds
in across the Central Appalachians and Mid-Atlantic. A tropical
system will drift north toward South Carolina, but may stall near
the coast. Confidence remains low on whether there will be any
signifcant impacts to the western Carolinas and northeast Georgia
early next week. The storm is expected to begin drifting east
off the coast later in the week, as high pressure builds in from
the north.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 131 PM EDT Saturday: An upper low is pivoting into
the southern Appalachians with drier air punching into the
mid-levels. Better upper divergence and DPVA has shifted east
of the region as most of the activity east of the mountains have
dissipated, leading to a lull in precipitation. However, with the
trough axis overhead the mountains, destabilization has occurred
with 500-1000 J/kg of SBCAPE as scattered convection is currently
ongoing. Weak deep layer shear will only support outflow driven
convection downstream and allow for this activity to develop east
of the mountains later in the afternoon into the evenings hours as
the trough axis pushes eastward as well. Thinking is coverage will
be less than originally forecasted as morning convection lasted
longer than expected and the atmosphere not having enough time to
recover. Drier conditions are likely by the early overnight period
as the once quasi-stationary front is pushed well east of the CWFA
with the better associated forcing lifting to the north and east
in response to the trough axis passage. Deepening ridge over the
Mid-MS Valley, with surface high riding underneath will filter in
drier northeasterly flow at the surface tonight into Sunday. As
a result, mentionable PoPs escape the forecast overnight, but
lingering moisture trapped underneath a nocturnal inversion should
allow for another deck of low stratus by daybreak Sunday. The
better moisture will be placed in the North Carolina Piedmont and
eastern Upstate, where the best chance for the low stratus deck to
develop. Overnight lows are expected to run ~5 degrees above-normal.
Drier atmospheric column expected Sunday as northeasterly flow
continues at the surface and much drier air settles in the
upper- and mid-levels. This will help to suppress convective
initiation outside of ridgetops along the Blue Ridge during peak
heating. Coverage will be of garden variety, while the rest of the
CWFA remains dry. Once low-level mixing commences, the low stratus
deck should quickly retreat by mid- to late morning Sunday. Better
insolation at the surface should help afternoon highs climb slightly
above normal for most locations.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 1:30 PM EDT Saturday: Confidence is increasing that TD Nine
(which will likely become Imelda in the next day or so) will
drift north toward the SC coast, but then stall as high pressure
builds over the Ohio Valley to the Mid-Atlantic. The storm may also
interact with Hurricane Humberto, which will be re-curving off the
east coast. Some most of the 12z guidance and latest ensembles
are trending toward having Imelda make a sharp turn to the east
before making landfall (and that is the latest NHC forecast). With
that said, there are still a handful of ensemble members that sneak
Imelda all the way to the coast and possibly drifting inland. Even
with the latest forecast keeping the center of Imelda just offshore,
easterly flow around the north side of its circulation will advect
a band of moisture across central NC and into at least the eastern
half of the forecast area Monday. The PWATs will ramp up to 1.5-2.0"
along the I-77 corridor Monday into Tuesday. The 12z GFS has an axis
of 2-4" of QPF in about 24 hours ending 00z Wed. But other guidance
keeps the heavier QPF closer to the coast. The Day 3 Slight Risk
on the Excessive Rainfall Outlooks over our southeastern part of
the forecast area looks good. Otherwise, it will be wedge-like
across the forecast area, as a 1022-1025 mb high persists across
northern Mid-Atlantic and eastern Great Lakes, keeping a breezy
NE flow and plenty of cloud cover from the moist easterly flow
aloft. Highs will be 5-8 degrees below normal, except near normal
in the central and western NC mountain valleys. And lows will be
8-12 deg above normal across the entire area.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 1:45 PM EDT Saturday: Forecast confidence is increasing
that the tropical system, which will likely be Imelda, will get
pushed east off the coast mid to late next week. This will be
thanks to strong high pressure building in from the north, and
possibly due to some influence from Hurricane Humberto which may
help pull the low as it makes its closest approach to the east
(but still hundreds of miles offshore). With that said, there are
still some ensemble members and hurricane models that bring Imelda
onshore and stall in somewhere in the area, which could result
in rain chances lingering longer than the latest forecast. But
those solutions appear to be the less likely scenario. As such,
the latest NBM has come in drier for Wednesday and the rest of the
week. Assuming the sfc high to our north wins out, PoPs taper to
20% or lower and temps trend further below normal.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Variable cigs continue to settle over the
area, but the trend is that most locations should go VFR over the
next couple of hours as low-level mixing continues to scattering
out low cigs. Scattered showers and thunderstorms have developed
over the mountains and the expectation is that this activity will
push east. In this case, kept the TEMPO for TSRA and associated
restrictions for this afternoon and evening at all TAF sites. Drier
air will filter in tonight as northeasterly winds push into the
area. Model guidance continue to place a low stratus deck over
a good portion of the region by daybreak Sunday, but drier air
may keep the deck from reaching KAND, possibly KGSP/KGMU. Kept
an IFR cig mention at all sites, but drier air may keep the
low stratus deck from reaching its full potential. Will have
to monitor trends for the 00Z update to see if restrictions are
needed, mainly at the Upstate sites, while confidence is higher
for the NC terminals. Otherwise, any low stratus deck and fog that
develops will scatter out by mid-morning as low-level mixing gets
underway. Much drier air in place during the day Sunday, so showers
and thunderstorms are not expected outside of a few developing in
the mountains. Confidence not high enough for a mention at KAVL
at this time. Northeasterly winds will pick up in speed during
the day Sunday at 5-10 kts, with possible sporadic low-end gusts.
Outlook: Drier conditions are expected on Sunday outside of
isolated diurnal showers and thunderstorms across the mountains
on Sunday. 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...ARK
NEAR TERM...CAC
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...CAC

NWS GSP Office Area Forecast Discussion