698
FXUS62 KGSP 181818
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
218 PM EDT Wed Sep 18 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 THURSDAY/...
A cutoff upper low continues to provide enuf lift to produce periods
-ra/dz over most areas. The srn and ern zones have seen increasing
insol and therefore deeper showers have formed there. Not a great
threat for thunder this afternoon as soundings still indicate only
arnd 200 J/kg of skinny sbCAPE. There could be a few isol strikes
later this afternoon, yet not enuf confidence is had to mention in
the HWO.

The upper low will lose any connection with the sfc pattern
overnight and slowly shift east of the FA thru the day on Thu. Still
expect a good amt llvl wrap around moisture in the wake, which will
be able to develop isol/sct pulse showers and possibly a few general
thunderstorms with increasing instability during the afternoon.
Overall, an improving pattern as far as lessening cloud cover and
temps will respond to arnd 80 F outside the mtns, a few degrees
warmer toward NE GA, and u70s mtn valleys. A dense fog threat is
possible arnd daybreak across the NC mtn valleys as better rad
cooling conds interact with a rather moist sfc layer. Lows will
generally be held a couple degrees abv normal.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 157 PM Tuesday: As we head into Friday and Saturday, upper
ridging will slowly drift east from the Southern Plains into the
Lower Mississippi Valley. Heights will rise through the period
across the Southern Appalachians with increasing subsidence. At the
surface, high pressure will extend down the spine of the
Appalachians form a parent high centered near the Hudson Bay.
Guidance still indicates the presence of a backdoor cold front
oozing into portions of the Carolinas from Virginia. A noticeable
change, however, is that guidance is less aggressive with clearing
the boundary through the area, thus keeping dewpoints in the low to
mid 60s. The airmass will be drier, relatively speaking compared to
the tropical origins of the current airmass, but PWATs may not fall
as appreciably. While a stray shower or two cannot be ruled out,
increasing subsidence from the building upper ridge will generally
preclude mentionable PoPs outside of the Blue Ridge escarpment on
Friday. Temperatures will continue to warm through the period with
highs back into the low to mid 80s.

&&

.LONG TERM /SATURDAY NIGHT 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 /18Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: A tricky TAF set in store as an upper low
continues to produce low clouds and VSBY issues. Expect some
improvement to VFR this afternoon, esp at KCLT. The wrn sites could
remain socked in (MVFR/IFR CIGs) for a while with deeper moisture
continuing to train and lift over the area. All sites will likely
drop to IFR, mainly due to CIGs, overnight with MVFR VSBY probable
as well. At KAVL, a good signal for a drying column as the low
shifts east thereby setting up a possible dense fog threat arnd
daybreak. Expect improving conds late period all sites to either
MVFR or VFR. Winds remain light thru the period favoring a ne/ly
direction.

Outlook: On Friday, sfc high pressure builds into the area from the
north allowing drier weather and VFR conditions to return into this
weekend.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...SCW
SHORT TERM...TW
LONG TERM...TW
AVIATION...SBK