381
FXUS62 KGSP 250557
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
157 AM EDT Sat May 25 2024

.SYNOPSIS...
Temperatures will remain above normal through the holiday weekend
with a chance of afternoon and evening thunderstorms. A cold front
brings another chance of showers and thunderstorms on Monday. Cooler
and drier conditions move in behind the front and remain through the
end of the week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 143 AM EDT Saturday: A passing short wave/MCV looks like it
will support the development of showers and a few thunderstorms
across the foothills and western Piedmont of NC through the
pre-dawn hours, so a chance was added back on this update. Think
we lack sufficient leftover buoyancy to allow for anything severe,
but expect plenty of lightning and some wind gusts maybe up to 40
mph in the stronger cells. Main thing is, it will probably wake
a few people up if it survives to the Charlotte metro area. The
rest of the forecast area should be more quiet, with mild temps
through daybreak.

Otherwise...areas that get rain this evening can expect some patchy
fog before dawn, but that won`t last long before skies clear. Lows
will fall into the mid-60s again. Another round of convection is
expected tomorrow, but should be even less active than today. Weak
ridging will begin to develop over the Southeast CONUS overnight,
and the only supporting upper feature for convection will be an
embedded shortwave that dips across the Appalachians and into
the Piedmont by afternoon. CAMs suggest that a line of showers
and thunderstorms will cross the area during the mid-afternoon,
organized more by their supporting upper feature than by any
inherent storm-scale dynamics.  Sans much of an upper wave to work
with, there`s pretty good consensus that deep shear will be <20kts,
and so severe risk looks muted compared to today`s.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
As of 205 AM Saturday: Sunday has the potential for a few more
diurnally driven convective storms as a weak shortwave moves across
the area. Guidance keeps a steady stream of moisture from the SW
during this time with PWATS well into the 1.5 inch range. GFS and
NAM indicate modest instability during the afternoon and evening
hours, supporting any initiation off the mountains. Outside of
somewhat weak upper support aloft, storms that do fire have the
potential to be strong to severe, with damaging winds and some hail
possible. Again this will be diurnally driven and more of the
typical summertime pattern the area is familiar with. Capped PoPs in
the slight chance for the Piedmont and chance in the mountains.
Meanwhile, an upper low forms over the southern plains and lifts NE,
bringing the chance for a weak FROPA across the mountains Monday,
increasing rain and TS chances once again. There is some model
disagreement when it comes to the timing of the boundary and peak
heating. GFS brings the FROPA into the mountains late on Monday
night, which would not provide good forcing for convection. However,
showers and thunderstorms are still likely given instability and
daytime heating. Modeled soundings show steep sfc-3km lapse rates
and modest muCAPE, but with a strong T/Td spread and inverted-V
supporting strong downdrafts. By Monday night, the FROPA should
slowly dissolve over the CWA and bring in a bit drier air and nip
rain chances through the end of the period.Temps will remain above
climo until the weak cold front when temps should cool a bit closer
to normal.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 210 AM Saturday: By Tuesday, a strong ridge builds over the
central CONUS, taking on an omega pattern over most of the CONUS,
leaving the CWA in a weak quasi-zonal regime from the base of the
trough to the north. Long range models show an upper trough dipping
southward from the Great Lakes, but don`t provide much support for
TS activity. There is still much uncertainty as to how far south and
if the trough reaches the CWA. By Wednesday, a weak low attempts to
form over eastern TX and sends a ripple in the upper flow. Possible
shortwaves could traverse the area Wednesday night and bring another
chance for showers/TS, but confidence is low. After Wednesday night,
the ridge axis from the central CONUS propagates eastward toward the
CWA and shunts rain chances with strong subsidence aloft. Dry
conditions return as heights quickly rise into the end of the
extended period. Temperatures should warm gradually and remain close
to climo through the period as well.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Dealing with some convection moving east
from the NC foothills to the western Piedmont over the next few
hours, necessitating a TEMPO at KHKY and also a TEMPO at KCLT for
passage of TSRA in the pre-dawn hours. The plan is for the storms
to be clear of KCLT before operations really crank up this morning
after 10Z. Once that is clear, would not be surprised if some fog
persisted until the sun comes up and mixes it out, but will not
include yet. Won`t rule out brief fog restrictions elsewhere. For
the balance of Saturday, VFR with sct/bkn low clouds, and a light SW
wind. Think the HRRR model has a plausible depiction of thunderstorm
evolution, so this was generally followed on the timing of a PROB30
group at all terminals. The storms should die off around sunset,
leaving us with convective debris clouds overnight, and possible
fog restrictions in the pre-dawn Sunday.

Outlook: A unsettled pattern will linger thru the rest of the
weekend and into early next week, allowing for diurnal shower and
thunderstorm chances each day and at least patchy fog development
each night/morning.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...JDL/MPR/PM
SHORT TERM...CP
LONG TERM...CP
AVIATION...PM