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000
FXUS62 KGSP 191742
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
142 PM EDT Fri Apr 19 2024

.SYNOPSIS...
Showers and thunderstorms are possible today as a cold front crosses
the area, with unseasonably warm weather through Saturday. Much
cooler temperatures and widespread light rain is expected Sunday
with drier weather on Monday. Drier and warmer weather will return
to the area Tuesday through next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 140 PM Friday: Heating has resumed with moderate CAPE
developing across the area. Moderate effective shear is also in
place. A short wave and cold front drop across the area this
afternoon. CAMs show this forcing will act on the instability to
develop isolated to scattered thunderstorms. With the moderate
shear and instability in place, a few strong to severe storms are
also expected with damaging winds and large hail the main threats.
Can`t rule out some storm organization given the shear, but chances
look limited for now.

Convection diminishes/moves east of the area this evening as the
cold front moves out of the area. Mid and high clouds will linger.
Low clouds across the mountains, and possibly an isolated shower
along the TN border, are expected overnight in the developing moist
NW flow. Lows will be 10 to 15 degrees above normal.

Some sunshine will be seen Saturday even though mid and high clouds
remain. Guidance disagrees on the development of moist low level
upglide during the afternoon as the cold front stalls just to our
south and an area of low pressure moves east along the front.
Guidance blend keeps the area dry, so have gone that way for now.
Thickness values are lower, so highs should be lower as well. Went
with the guidance blend which has highs near normal for the
mountains and around 5 degrees above normal elsewhere. Of course, if
the cloudier or wetter guidance is correct, then lows would end up
cooler.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 200 AM EDT Friday: The near-term cold front is forecasted to
be well south and east by the start of the forecast period as the
frontal boundary stalls over the Gulf Coast. An active baroclinic
zone will develop across the Deep South/Gulf Coast and help aid in
widespread showers and thunderstorms in these regions as a series of
surface waves develop and ride along the stalled front. Enough
differential heating and a northward ripple of the boundary due to a
passing surface wave could set the stage for isolated convection
near the vicinity of the boundary Saturday afternoon, mainly in
locations along and south/east of I-85. Otherwise, dry air
entrainment will gradually filter in behind the front and should
allow for a pleasant day for most locations Saturday. Highs will be
4-8 degrees above normal for highs across the Piedmont, while near-
normal values are expected across the mountains. Model guidance are
in decent agreement with developing a weak coastal low along the
boundary Saturday night into Sunday along the east-central Gulf
Coast. The current track has this feature slipping across the S
GA/FL Panhandle and offshore the Southeast Coast. Bizarre in-situ
wedge will settle in as the parent surface high slides into the
Southern Plains and a piece of this area of high pressure breaks off
and sets up shop over the Mid-Atlantic Saturday night into Sunday.
In this case, high temperatures will drop ~15-20 degrees on Sunday
compared to Saturday. The precip shield associated with the coastal
low will bring rainfall to the area Sunday and essentially lock in
any kind of wedge that develops. QPF response will be light to
moderate, with the southeastern zones expected to receive the most
rainfall.

The coastal low slips further offshore the Southeast Coast Sunday
night as the aforementioned parent surface high propagates eastward
and stretches from the Lower MS Valley through the Mid-Atlantic.
Cooler thicknesses will move over the area Sunday night as a stout
shortwave trough quickly shifts across the central CONUS and
knocking on our front door by the very end of the period. Factor in
continued north-northwesterly flow in the low-levels and weak CAA,
overnight lows are expected to be in the 40s for most locations,
with values flirting with the 30s in the higher elevations.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 315 AM EDT Friday: Lingering in-situ wedge is shown eroding by
Monday as the aforementioned surface high shifts across the
Carolinas and into the northeastern CONUS, while the shortwave
trough slips overhead and offshore by Monday night. This will keep
temperatures ~10-15 degrees below normal for most locations Monday.
Low-amplitude upper ridging will traverse across the CFWA Tuesday
into Wednesday, which will allow for the airmass to modify as highs
rebound to slightly below normal Tuesday to at or just a tad above
normal for afternoon highs on Wednesday. A potent shortwave trough
will move into the region later Wednesday into Thursday with an
attendant frontal boundary. Model guidance are not excited about the
potential impacts as the boundary will move into a moisture starved
environment and lack thereof forcing as better forcing will reside
north of the area. Best PoPs will stay confined to the immediate
Tennessee border before rain chances dwindle east of the state line.
Temperatures should remain near-normal through the end of the week,
with a mainly quiet pattern in store to round out the extended
forecast period.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Low VFR cumulus will continue to develop
through the afternoon. Expect convection to develop as well. Have
timed TEMPOs to show the best timing for storms. Kept it out of KAND
for now since they have a lower chance of seeing storms. WSW wind
this afternoon for all but KAVL where NNW wind continues. Convection
ends this evening with mid and high clouds remaining over the area.
MVFR cigs and vsby develop at KAVL overnight. Chance of restrictions
elsewhere is low. Light W to NW wind overnight. N wind picks up
speed with gusts at KAVl after daybreak. Low clouds scatter out but
mid and high clouds continue.

Outlook: Rain and possibly isolated thunderstorms are expected to
develop on Sunday as a low pressure center moves by just south of
the area, likely resulting in restrictions for at least the southern
part of the area. Drier conditions return Monday, continuing into
Tuesday. A weak cold front moves in from the NW Wednesday, but
chance of precip and associated restrictions is uncertain.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...RWH
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...RWH