123
FXUS62 KGSP 200608
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
208 AM EDT Mon May 20 2024

.SYNOPSIS...
Warming high pressure will build atop the region through the first
half of the week. Along and ahead of a stalling cold front, showers
and storms return on Thursday with chances continuing all weekend.

&&

.NEAR TERM /THROUGH TODAY/...
As of 150 AM: Weak sfc high now centered over Virginia, beneath
positively tilted upper ridge. Sfc winds are almost all calm
following apparent decoupling Patchy stratocu are seen along the
Appalachians from WV to NE GA where weak low level flow bears an
easterly component. Observed cloud heights suggest some of these
are being generated by shallow convection beneath subsidence
inversion; they generally look to persist in the NW half of the
CWA thru daybreak, although likely variable in coverage. Dewpoint
depressions are small across the board, but especially so in the SE
area where skies have been clearest. NAMNest and HRRR depict some
fog/stratus forming via radiation but so far have appeared overdone
in their extent. Shallow nature of the moist layer suggests any
fog will be similarly transient to the aforementioned cloud decks.

Today, flow will veer to SE as sfc high builds slightly further
south and east. Still looks like the resulting upslope flow will
trigger some isolated convection over the mountains owing to a
few hundred joules of SBCAPE, but still with tame PWATs of around
an inch by peak heating, weak shear, and plenty of dry air to
entrain. Not particularly concerned for severe wx or for flash
flood threat although any cells will be slow-moving.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
As of 1205 PM EDT Sunday: The warming trend will continue through
the forecast period as lower elevation max temperatures climb into
the middle 80s by Wednesday.  Building upper ridge atop the SE CONUS
will keep the atmosphere suppressed, save for diurnal isolated
ridgetop deep conection in the NC mtns Tuesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 100 PM EDT Sunday: With developing lee trough and some
downslope warming, Thursday has the potential to be the hottest day
of the week with piedmont upper 80s possible, as long as convective
and/or debris clouds limit insolation too early in the day. It looks
like an active frontal zone is progged to approach and stall in or
near the cwfa on Thursday as it becomes parallel to the upper flow.
This baroclinic zone should be able to aid in showers and tstms
becoming numerous, especially across the mountains Thursday
afternoon.  Within the wavy quasi zonal flow atop the region Friday
and into next weekend, daily, diurnally enhanced tstms are probable
each day with temperatures averaging above the late May climo.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: NE PBL flow continues via weak sfc high
centered over Virginia. Mountain valley fog and stratus expected
to persist through daybreak, with generally LIFR to VLIFR at
KAVL. Otherwise, stratocu are being generated apparently via weak
convergence and/or upslope east of the Blue Ridge Escarpment,
with distinct layers at 030-040 and 060-080. Think these clouds
are likely to be seen over all the terminals at some point before
12z, with periodic cigs possible, but cigs not likely to last
long enough to allow valley fog to dissipate. Some sources depict
radiation fog in the Piedmont in the predawn hours but presently
not expected to extend to TAF sites. The NE winds will continue
until early afternoon, with diurnal cu forming at MVFR to low VFR
level but probably not causing cigs. Winds go SE with aftn mixing
and southward migration of sfc high. Ridgetop SHRA or even TSRA are
possible but chance still not mentionable at KAVL. SE flow tonight
will produce low stratus near the Escarpment, and MVFR is possible
at KAVL after 06z, along with valley fog. Otherwise VFR tonight.

Outlook: High pressure remains dominant over our area thru
Wed, but isolated mountaintop convection still expected each
afternoon. Precip and restrictions possible with next front arriving
late Thu or Fri.

&&

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

&&

$$

SYNOPSIS...CSH
NEAR TERM...Wimberley
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...Wimberley