420
FXUS62 KGSP 251424
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1024 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 TONIGHT/...
As of 1020 AM EDT Saturday: Ongoing complex of showers and storms
moving in from the southwest mountains of NC and northeast GA.
Expect this area of activity to continue marching across the area,
but CAMs want to fizzle it out before completing a CFWA sweep. We`ll
have to continue to monitor trends in the environment as we approach
peak heating. Adjusted PoPs and temperatures based on current
observations and latest trends.

Strong to severe thunderstorms will again be the primary concern
across the forecast area, mainly this afternoon and evening, in
particular because of all the outdoor activities this weekend. Weak
ripples in the flow, along with smaller MCVs, will help to
trigger and loosely organize new shower/thunderstorm development
today. The CAMs are in something of an agreement with new storms
developing/reorganizing over the mtns in the early/mid afternoon
and then moving out over the foothills/Piedmont through the early
evening. Altho the shear today will not be as good as yesterday,
perhaps effectively 20 kt from the NNW at best, we might make up
for it a bit with better sfc-based CAPE, more like 2000-3000 J/kg
during peak heating. Suspect we will be able to equal our Svr Tstm
Warning total from Friday, so be on the lookout. High temps will be
5-7 deg above normal. For tonight, the convection will slowly wane,
but would anticipate the arrival of another remnant MCV possibly
overnight, superimposed on the flat broad upper ridge over the
Southeast/Carolinas. Min temps will be at least five deg above
normal again.

&&

.SHORT TERM /SUNDAY 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. Kept PoPs
higher across the mountains and in the slight chance range for the
Piedmonts. 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 /15Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Dealing with some convection moving
east from the northeast GA and southeast NC, but the model guidance
are keen in having this dissipate before reaching the TAF sites. Mid
to high clouds in association with the convection will continue to
roam the sky. For the balance of the day, 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 TEMPO or 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...CAC/PM
SHORT TERM...CP
LONG TERM...CP
AVIATION...CAC/PM