143
FXUS62 KGSP 140138
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
938 PM EDT Tue Aug 13 2024

.SYNOPSIS...
Dry high pressure gradually builds in from the north through
Thursday, pushing a stalled front further south of the area. The
high will drift east off the East Coast Friday, as a cold front
approaches from the west over the weekend. The front will bring a
return of better chances of shower and thunderstorms through Sunday,
then lower chances early next week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 928 PM EDT Tuesday: Several showers continue to fester across
the Upper Savannah River Valley within a pinched off instability
corridor. These showers should dissipate over the next several hours
as instability wanes. Otherwise, dry low-level air will filter into
the area within northeast flow. Patchy fog, some of which could be
locally dense, will be possible across the mountain valleys and
portions of the foothills generally along the I-40 corridor where
moisture can pool along the escarpment. The extent and magnitude of
fog will be governed by how much dry air filters into the region,
thus confidence in development isn`t high outside of the
aforementioned areas.

For Wednesday, the NW flow aloft is maintained by the model
guidance, with no mid/upper forcing to speak of. Meanwhile,
weak high pressure will ridge down from the north to give us a
decent day, with more sun across more of the area. Fcst soundings
are generally unfavorable with only shallow instability over the
mtns. All of the CAMs manage to develop shower activity on the E
side of the mtns, so a chance will be included near the Blue Ridge
Escarpment for the afternoon hours. Seems like a good bet. The
high temp fcst looks more uniform, with a nice rebound over the
NC foothills and western Piedmont, maybe five degrees warmer,
but maybe five degrees cooler over northeast Georgia.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 200 PM EDT Tuesday: NW flow will be in place across the area
as we move into the short term Wednesday night, with upper troughing
down the East Coast. Upper ridge will be building up the MS Valley,
and surface high pressure in place over the Carolinas and Mid-
Atlantic. Fairly quiet, seasonable temperatures on Thursday with low-
end pops mainly in the mountains due to the light upslope flow. As
the wavetrain moves east for Friday, the ridging will push east and
over the Appalachians and an upper trough will begin to work into
the upper Midwest, dragging a front through the OH Valley.
Temperatures will increase somewhat in response to the building
ridge, and forcing from the approaching wave and attendant surface
front warrants increased pops at least in the mountains by Friday
afternoon, with less confidence further south.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 215 PM EDT Tuesday: The aforementioned front will be on our
doorstep as we move into the extended, pushed by an upper low
working its way from the Upper Midwest across the Great Lakes
through the weekend. The front pushes through during the weekend
while it will be strongly occluded with limited moisture, upper
forcing and and hints of some deep layer shear as it passes to
warrant keeping an eye on to provide some organization to the
convective potential especially for Saturday. The longwave trough
sets up over the Appalachians in the wake of the front but guidance
is in disagreement on whether or not our area is still on the
upslope and unsettled side or on the downslope and drier side. For
now, temps remain just above normal with low-end pops mainly in the
mountains.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: A northeast flow pattern will remain in place
across the region through the TAF period. Showers and a stray storm
continue to fester along the Upper Savannah River Valley in a
corridor of higher instability this evening. A shower may stray
close to KAND over the next hour or so, otherwise no convective
impacts are expected at any other terminals. The main focus
overnight will be the potential for a deck of low stratus and
perhaps patchy fog to develop, especially across the mountain
valleys and I-40 corridor into the Upstate. Confidence in
restrictions is highest at KAVL and KHKY with temporary restrictions
possible at KGMU/KGSP. A few afternoon showers will be possible
across the mountains tomorrow afternoon.

Outlook: Expect mostly diurnal isolated to scattered diurnal
convection through Thursday. Coverage of convection increases Friday
into Saturday as a cold front approaches out of the west. Patchy fog
and low stratus will be possible each night in the mountain valleys
and in any locations that received heavy rainfall the day prior.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...PM/TW
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...TW