344
FXUS62 KGSP 200730
AFDGSP

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

.SYNOPSIS...
Warm high pressure will persist across the region through the
middle of the week. A cold front approaches from the northwest on
Thursday, bringing a chance of showers and storms mainly to the
mountains. The front will stall over the area Friday, keeping rain
chances through weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 315 AM: Weak sfc high now centered over Virginia but extending
thru our CWA, supported by positively tilted upper ridge. Sfc winds
are very light or calm around the area owing to weak gradient
and decoupling. Patchy stratocu are seen along the Appalachian
foothills from WV to 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 along/SE of I-85 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. Max temps will rebound back to normal or even a
couple degrees above. Some cumulus will break out beneath the weak
inversion across the area. Despite that, most prog soundings over
the mountains depict some skinny CAPE developing, perhaps a few
hundred J/kg. With upslope flow some convection is expected to
fire there. Tame PWATs of generally an inch or less, mostly via
low to midlevel moisture. Profiles are quite dry above 700 mb. Dry
air entrainment will keep coverage isolated or widely scattered
at best. Not particularly concerned for severe wx or for flash
flood threat, but will point out any cells will be slow-moving
and fairly healthy accums still may be seen. This activity will
wane diurnally. SE flow will result in some areas of cloud cover
persisting near the Blue Ridge Escarpment, similar to what we`re
seeing this morning, and with dewpoints not expected to mix out
much this aftn. Mins near normal.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 AM EDT Monday: An upper ridge axis extending from the
Gulf of Mexico northeast along the Appalachians will keep the
atmosphere rather suppressed atop the forecast area thru the short
term. Isolated showers and perhaps a couple of garden-variety tstms
may develop along the ridgetops with strong daytime heating. But
otherwise, just some fair wx cu and temps continuing a warming
trend. Highs will be in the mid 80s on Tuesday and mid to upper 80s
Wednesday across the lower mountain valleys and the Piedmont. Lows
will be mainly in the 50s in the mountains and lower to mid 60s
elsewhere.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 315 AM EDT Monday: Thursday has the potential to be the
hottest day of the week with highs approaching 90 degrees in parts
of the lower Piedmont. However, convective debris clouds may spill
over the area from the west, as upper flow begins to flatten out,
and this may limit insolation. While shortwave energy works to
flatten the eastern CONUS ridge, guidance still is in disagreement
on how far east an approaching cold front will get to our area. The
ECMWF continues to keep Thursday dry, while the NBM PoPs suggest
at least scattered diurnal convection returns to the mountains
and possibly the I-40 corridor east. The front should sag into
the area Friday, as a more pronounced wave rides thru the upper
flow across the region. This should provide for better diurnal
convective coverage Friday, with more shear and instability for a
few strong storms. Then the front basically stalls out across the
Southeast, as it becomes oriented parallel to the upper flow. So
above climo PoPs looks on tap for the weekend with temps remaining
a few degrees above normal.

&&

.AVIATION /08Z 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...ARK
NEAR TERM...Wimberley
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...Wimberley