845
FXUS62 KGSP 140540
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
140 AM EDT Wed Aug 14 2024

.SYNOPSIS...
Dry high pressure gradually builds in from the north through
Thursday, resulting in mainly isolated afternoon showers and
thunderstorms in the mountains. 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 TODAY/...
As of 1230 AM EDT Wednesday: Isolated showers over the western SC
Upstate have finally dissipated. Dry conditions are expected to
linger through the rest of this morning. Made some tweaks to PoPs
and thunder chances through the period but no other changes were
needed at this time as the forecast remains on track. Otherwise, dry
low-level air will filter into the area within northeast flow.
Patchy fog 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 on development remains low.

For the rest of today, 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. Forecast soundings are
generally unfavorable with only shallow instability over the
mountains. All of the CAMs manage to develop shower activity over the
North Carolina mountains, with the best coverage expected along the
central and southern Blue Ridge Escarpment this afternoon. Highs
today will be warmer temps over the NC Foothills and Piedmont and
the eastern SC Upstate. However, slightly cooler temps are expected
across the Little TN Valley and Upper Savannah River Valley.

&&

.SHORT TERM /TONIGHT 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 /06Z WEDNESDAY THROUGH SUNDAY/...
     Key Messages...

1) Patchy Fog and Low Stratus are the Main Concerns through Daybreak
at KHKY and KAVL

2) Scattered Showers will Develop at KAVL this Afternoon with Dry
Conditions Lingering Elsewhere

3) Mostly MVFR to VFR Cigs Expected through the 06Z TAF Period

At KCLT and elsewhere: Dry conditions will continue through this
morning. Patchy fog and some low stratus have already developed at
KHKY. Patchy fog and low stratus may also develop at KAVL but
confidence remains low as the terminal did not see fog or low
stratus the night before. Nonetheless, have TEMPOs at both KAVL for
IFR fog. Seeing mostly MVFR to VFR cigs as of 06Z. Cigs should
mostly remain at these levels through at least daybreak, although
cloud cover is expected to gradually decrease through sunrise.
Mostly calm to light N/NE`ly should continue through daybreak as
well. Winds east of the mountains will remain NE through Wednesday
morning before gradually turning more ENE/E this afternoon. Winds
will then gradually toggle back NE this evening into tonight. Winds
are starting out SE at KAVL this morning but should gradually turn
N/Ne after daybreak. KAVL will then see winds turn SE`ly this
afternoon into this evening. Have a PROB30 for -SHRA at KAVL this
afternoon as showers are expected to develop across the mountains.
Dry conditions should persist elsewhere. Mountain valley fog and low
stratus may develop tonight into daybreak Thursday, with KHKY
looking to have a lower fog potential compared to this morning.

Outlook:Isolated diurnal convection returns 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
morning 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...ARK
NEAR TERM...AR/PM/TW
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...AR