981
FXUS62 KGSP 260801
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
401 AM EDT Sun May 26 2024

.SYNOPSIS...
Temperatures remain above normal through the holiday weekend. A
chance of thunderstorms Sunday afternoon and into the overnight,
with a cold front bringing another chance of showers and
thunderstorms on Monday. Cooler and drier conditions return through
the end of the week.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 342 AM EDT Sunday: All quiet across the fcst area for the
time being. Still some concern about fog thru daybreak, but that is
becoming more questionable as a thickening cirrus shield from the
central Plains convection drifts overhead. We will monitor. Temps
will remain mild.

The severe thunderstorm potential is the main concern over the next
24-36 hours, with more than one wave/episode of greater severe
risk. Our brief quiet period should come to an end starting in
the west late this morning as the latest in a series of remnant
MCVs moves in from the west. This wave is the one responsible for
the severe weather over the srn Plains this past evening, and it
should move over our region in the afternoon/early evening. The
convective environment will be no slouch for this time of year. The
models develop most-unstable CAPE upwards of 2500-3500 J/kg during
peak heating, while increasing mid-level flow raises the deep
layer/effective shear into the 40-50kt range. Any storm that
develops in that environment stands a good chance to acquire
supercell characteristics. Storms will be moving right along in
the fast westerly flow, so the primary concern will be damaging
wind gusts, particularly if cold pools merge east of the mtns as
convection grows upscale in the evening. The upscale growth may
become more of a factor east of our fcst area, however, so we
will also have to deal with large hail. The trend in the HRRR is
to show more potential for updraft helicity streaks, which raises
the risk for brief tornadoes in any embedded supercells. However,
the 0-1km shear/storm-relative helicity looks...wanting...over
the area east of the mtns, so we will keep the tornado mention
isolated for now. Be on the lookout for the strong/severe storms
in the mid-afternoon to mid-evening time period, and anticipate
a severe weather watch at some point later today. High temps will
be nearly ten degrees above normal.

After this first wave passes, we should enter into a relative
lull in the action for late evening/early morning Monday, during
which time our attention turns to the west in anticipation of the
next wave of severe potential. The CAMs show good agreement with
a squall line developing along or ahead of the cold front/main
short wave axis across the TN Valley region late tonight, which
would ram into the mtns some time between midnight and daybreak
Monday. The HRRR in particular suggests a good potential for a
line of severe storms with embedded pockets of wind damage all
along the line moving over the mtns roughly 09Z-12Z Monday, before
it runs out of fuel and outruns the mid/upper support crossing the
mtns around daybreak. Interests over the NC mtns should anticipate
the potential for another Severe Watch in the early morning hours
Monday, mainly for wind gusts. Low temps will remain mild.

Monday becomes more of a toss-up, with a dying MCS over the
fcst area in the morning hours that should bring extensive
cloudiness. The question becomes...will we be able to get rid of the
clouds and destabilize in the afternoon?  The HRRR seems to think
so. That being the case, there would be another round of severe
storm potential mainly east of the mtns in the afternoon. The RAP
develops sfc-based CAPE 2000-2500 J/kg and retains enough shear to
loosely organize storms and push them along. Colder mid-level temps
suggest this could have better large hail potential. Confidence in
this scenario is less than the previous two discussed, so precip
probs will be limited mainly to the chance range. High temps should
once again be 5-10 deg above normal.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 200 AM Sunday: Picking up Monday night, the upper low lifts
off toward the NE and any remaining boundary should be out of the
area by this time. A few lingering showers are depicted by the GFS
and EURO, but should dissipate overnight. The FROPA starts to allow
drier air to filter into the CWA, dropping the humidity a bit and
bringing temperatures closer to normal. Tuesday could see a stray
shower over the mountains during the daytime hours, however
confidence is very low given the decreased moisture availability.
Will keep unmentionable PoPs at this point. Temps will be warmest
Tuesday during the short term and decrease a tick or two closer to
climo by Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 200 AM Sunday: By Wednesday, a semi-strong omega blocking
pattern continues over the CONUS, leaving the CWA in a weak quasi-
zonal regime from the base of the trough to the north. Synoptically,
this will leave the area open for NW flow aloft through at least the
end of the work week. There could be some remnant moisture and
unsettled forcing exiting the area by Wednesday night with a chance
for precip, but confidence is low as models continue to trend drier.
After Wednesday night, the ridge axis from the central CONUS
propagates eastward toward the CWA and shunts rain chances with
strong subsidence aloft. By Saturday, the ridge axis should be over
the region, continuing quieter weather. Temperatures should remain
close to climo through the period as well.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions will continue at all terminals
through the early morning hours, but there remains concern about
fog restrictions developing in the pre-dawn hours. Satellite
imagery shows the fog in the Little TN River valley, but the fog
development might be halted by the arrival of a cloud deck moving
in from the west before sunrise. We will monitor, but starting to
look like a lower threat at KAVL. For today, wind should remain
light S to SW. Scattered thunderstorms develop in the afternoon
hours so all terminals get a PROB30 for now until we can nail
down the timing with more certainty. Cloud debris after sunset
with storms dissipating. After that, our attention turns to the
west with the arrival of a line of storms well after midnight.

Outlook: A unsettled pattern will linger into the early part of
the 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...PM
SHORT TERM...CP
LONG TERM...CP
AVIATION...PM