655
FXUS62 KGSP 190622
AFDGSP

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

.SYNOPSIS...
The remnants of the coastal low will gradually dissipate or move
off the Mid Atlantic coast by Friday.  Meanwhile, high pressure
begins to build into the region from the north and west giving our
region a dry weekend. Temperatures will be near normal.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 AM Thursday...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 206 PM EDT Wednesday: A warming trend will continue Sunday
into early next week as the axis of the upper ridge becomes centered
over the Appalachians. Warming H85 temperatures and deep/efficient
mixing of the boundary layer will promote high temperatures in the
mid to upper 80s on Sunday, which will likely be the hottest day of
the period. A few locations may even reach the 90 degree mark across
the Upper Savannah Valley. The forecast will remain dry, however, as
a stout subsidence inversion present on forecast soundings deters
any convection. By Monday into Tuesday, a shortwave trough swinging
across the Midwest will drag a cold front towards the area. Timing
of the trough and attendant front remains elusive at this time
range, but a gradual uptick in PoPs will be warranted across the
mountains as the boundary nears.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: A mid-level low continues to spin over the
terminal forecast area, producing a lot of 5000-10000 ft clouds. But
plenty of breaks in those clouds are allowing radiation fog and LIFR
stratus to form in spots. For the rest of the night thru daybreak,
it is challenging to forecast how much of the fog and low cigs will
form at the TAF sites, but will continue to show some development
in the 06z TAFs. Note that in the mtn valleys, the fog could drop
the vis down into the LIFR category and VLIFR is not out of the
question. From there, fog and stratus should gradually improve to
VFR late morning thru 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. Will add PROB30 for SHRA at KAVL and KHKY where chances
are highest. Wind will be light N/NE or calm. Some redevelopment of
patchy fog and low stratus will be possible across the area tonight,
so will show some vsby reduction at KCLT beyond 06z tonight.

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...DEO
NEAR TERM...ARK
SHORT TERM...CAC
LONG TERM...TW
AVIATION...ARK