441
FXUS62 KGSP 171743
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
143 PM EDT Tue Sep 17 2024

.SYNOPSIS...
The remnants of the coastal low will meander over the region and
keep elevated rain chances across the area into tonight.  By
Wednesday, the remnant low will stall out over the Mid-Atlantic,
while high pressure begins to build into the region from the north
and west late in the week giving our region a dry weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages:

1) Remnants of Potential Tropical Cyclone Eight Continue Weakening
as it Drifts Across the Western Carolinas

2) Additional Flooding is not Expected Due to Low Rain Rates

As of 1200 PM EDT Tuesday: Made some minor tweaks to PoPs based on
the latest KGSP radar loops. Otherwise, the forecast remains on
track this afternoon.

For the rest of today, the story will be a generally low overcast
sky with spotty light rain/drizzle lingering across much of the
forecast area. The remnants of PTC 8 will remain stalled over the
Upstate this afternoon, then wobble east and then north tonight.
Additional showers are progged to form mainly on the west and north
sides of the circulation, which means highest PoPs will extend from
the northern Upstate thru the Central and Northern NC Mountains. The
southern Upstate and the Charlotte area should be on the drier side
of the circulation, but still could see a few periods of light rain
or drizzle. Highs will be well-below normal under the clouds.

Tonight, with the low still wobbling over the area, continued cloudy
skies and showery conditions expected. QPF should be light. Lows
will be slightly above normal.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 135 AM EDT Tuesday: The leftovers from Potential Tropical
Cyclone 8 will evolve into a weak closed upper low centered
right over the CFWA and meander over the area through the
day Wednesday into Wednesday night. The combination of the
closed upper low and above-normal PWAT values (~1.50"-1.75")
will support elevated coverage of showers, which is represented
well with likely PoPs (55%-70%) over the NC mountains and chance
PoPs (25%-54%) elsewhere. Model guidance suggests a few hundred
joules per kilogram of instability may develop across the CFWA
during peak heating Wednesday, which could lead to a few embedded
thunderstorms as well. Rain chances will linger into the nighttime
period Wednesday as the upper closed low begins to open up into a
shortwave trough and gradually lift into the northeastern CONUS
by late Thursday. Dry air entrainment will begin to take place
as upper/mid-level north-northwesterly flow filtering in as the
shortwave trough axis shifts east of the CFWA. Lingering showers
may remain in place over the favorable upslope regions over the
mountains late Thursday, but the expectation is that rest of the
area will dry out by the end of the forecast period. Temperatures
are expected to remain a few ticks below normal for afternoon
highs both Wednesday and Thursday, while overnight lows run at or
slightly above normal thanks to extensive cloud cover and increased
rain chances.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 AM EDT Tuesday: Changes in the synoptic pattern becomes
evident in the extended forecast period as any lingering upper
troughiness begins to lift out the region and a stout upper
anticyclone sets up shop over northern Mexico and the Southern
Plains. Over the weekend, the upper anticyclone will pivot eastward
and allow for gradual height rises to move into the southeastern
CONUS. At the same time, weak surface ridging will result in a drier
airmass and lead to much improved sensible weather conditions with
afternoon highs and overnight lows at or slightly below normal
for much of the medium range. The upper ridge over the central
CONUS will begin to breakdown and large scale changes start to
take place beyond D7, but the current D4-D7 deserves two thumbs up.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Another messy 18Z TAF forecast can be
expected thanks to the remnants of Potential Tropical Cyclone (PTC)
Eight meandering over the western Carolinas. Seeing BKN to OVC IFR
to MVFR clouds across the terminals this afternoon with -SHRA
confined to the SC Upstate terminals and KAVL. Have TEMPOs through
22Z across the SC Upstate terminals for -SHRA and IFR cigs with
prevailing -SHRA  and MVFR cigs at KAVL through 00Z. Most terminals,
except KAVL, will likely see a brief period of drier conditions this
evening before moisture returns overnight. Both cigs and vsbys
should gradually lower late this evening into the overnight hours
with the return of -SHRA. Thus, have PROB30s across all terminals
overnight to account for LIFR/IFR vsbys and cigs. -SHRA looks to
linger through at least Wednesday morning, which will act to keep
LIFR to IFR cigs and vsbys around so have TEMPOs during the morning
hours on Wednesday for all terminals. Restrictions will once again
be slow to improve on Wednesday, but by the afternoon and early
evenings hours vsbys/cigs should gradually improve to MVFR to VFR
levels. Wind direction will be primarily NE across the SC Upstate
terminals through Wednesday while winds at KHKY and KCLT will
generally be E/ESE. Winds at KAVL will generally have a N`ly
component and will be VRB at times.

Outlook: A weak upper low will lift northeast late Wednesday into
Thursday. Restrictions return again Wednesday night into Thursday.
On Friday, sfc high pressure builds into the area from the north
allowing drier weather and VFR conditions to return.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...AR/ARK
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...AR