553
FXUS62 KGSP 191048
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
648 AM EDT Thu Sep 19 2024

.SYNOPSIS...
Lingering moisture from the remnants of the coastal low
from earlier in the week will promote one more day of scattered
showers today, mainly across the mountains and I-40 corridor.
Coverage is more confined to the mountains on Friday. Meanwhile,
high pressure begins to build into the region from the north and
west giving our region a dry weekend. Temperatures will be at
or above normal through the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 645 AM Thursday...Stratus has become pretty extensive across
most of western NC and oozing south into the northern Upstate. Also
patchy fog in some of the mountain valleys and the NE GA Piedmont,
but not as much coverage as earlier guidance was showing. Updated
the sky grids to try to reflect the trends on satellite and the
METARs. Still expect the clouds to start lifting and scattering
out late morning thru the aftn. Temps and PoPs look on track.

Otherwise, an upper low is finally opening up as it drifts east
across the Carolinas today. This places the forecast area in
deep-layer NLY flow. At the sfc, a weak sfc high over the eastern
Great Lakes will keep a light NELY flow across the area. The
morning will start out mostly cloudy with areas of fog and low
stratus, but should see a decent amount of breaks in the clouds
by early to mid afternoon. Temps will continue a warming trend,
with highs getting into upper 70s to lower 80s in the lower
mountain valleys and the Piedmont. This combined with dewpts in
the mid 60s should result in a little more instability. So expect
another round of mainly scattered diurnal convection developing,
with isolated tstms possible. Not expecting any severe storms,
as CAPE will still be modest at best. But locally heavy rainfall
and gusty winds cannot be ruled out.

Tonight...Convection may linger into the evening, as activity drifts
south out of VA and extreme NW NC. But this activity should be on
a weakening trend and not expected to be organized. With less mid
and high clouds expected than last couple nights, may see a better
radiation fog night with possibly some low stratus developing as
well. Lows will be a category or so above normal.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 145 AM EDT Thursday: The CFWA will be situated between the
departing shortwave trough lifting into the northeastern CONUS and
an upper anticyclone over northern Mexico and the Southern Plains at
the beginning portion of the forecast period. As a result, expect
for increasing subsidence over the area as higher heights filter
into the CFWA through much of the period as upper ridging slowly
propagates eastward and essentially shuts down rain chances for most
locations. Surface high will sliver down the Appalachians from the
Atlantic Canada/Hudson Bay area and keep dry conditions in place,
outside of a slight chance PoP over the Blue Ridge Escarpment on
Friday. Drier airmass will be in place, but model guidance have a
hard time sending a backdoor front this far south in response to
the area of high pressure nosing into the region. In this case,
dewpoints will remain in the 60s, with increasing temperatures and
thus, a drier but still humid airmass will remain in place. Not much
change in the sensible weather for Saturday, but the upper ridge
axis will continue to make a run at the southeastern CONUS from
the west, so afternoon highs for Friday will be a few ticks above
normal, while Saturday`s afternoon highs uptick to a category or
two above normal. Overnight lows will run a few ticks above normal
for both Friday and Saturday night thanks to elevated dewpoints
despite better radiational cooling conditions.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 320 AM EDT Thursday: Upper ridge axis will continue to
track across the southeastern CONUS and pass through the CFWA by
early next week. As a result, temperatures will remain elevated as
warm air aloft promotes our warmest day to be Sunday with afternoon
highs almost two categories above normal, while afternoon highs
Monday and Tuesday are forecasted to be at or slightly above normal.
A shortwave trough will be in the midst of swinging across the
Midwest with an attendant cold front encroaching the CFWA from the
west as the upper ridge axis slips east of the area. Overall timing
and placement of said cold front is still uncertain amongst model
guidance, but the synoptic setup is relatively in-check. A gradual
uptick in PoPs will be presented in this scenario as the frontal
boundary inches closer to the region, with an emphasis on increasing
PoPs across the mountains during the medium range. Temperatures are
forecasted to return back to normal or even a few ticks below normal
by D6/D7 with more cloud cover and mentionable PoPs returning back
into the forecast.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Fairly extensive LIFR to MVFR stratus
continues to expand southward across the NC and SC Piedmont,
while stratus and some fog is socked into the mountain valleys. The
southern edge of the IFR stratus may get to GSP/GMU by 12z, Overall,
the low CIGS should slowly improve to MVFR by late morning, then
VFR by midday or early aftn.  Diurnal convection is expected
to form across the NC mountains mid to late aftn, but little
of that activity will be able to drift south-southeast into the
Piedmont. So PROB30 will only be carried at KAVL and KHKY where
chances are highest. Some of the high-res guidance has showers
reaching KCLT late evening or overnight, but confidence is still
too low to mention in the TAF. Wind will be light N/NE or calm. Some
redevelopment of patchy fog and low stratus will be possible across
the area tonight, mainly in the mountain valleys and NC Piedmont.

Outlook: On Friday, sfc high pressure builds into the area from
the north allowing drier weather and VFR conditions to return thru
this weekend. No appreciable return of moisture or precip chances
expected until early to middle of next week.

&&

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

&&

$$

SYNOPSIS...CAC
NEAR TERM...ARK
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...ARK