451
FXUS62 KGSP 081739
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
139 PM EDT Tue Jul 8 2025

.SYNOPSIS...
Hot and humid conditions will cool closer to normal late
this week with numerous afternoon and evening showers and
thunderstorms. The heat builds again from late in the weekend into
early next week as an upper ridge forms, but daily afternoon and
evening shower and thunderstorm chances continue.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 1207 PM Tuesday: Broad Bermuda ridge extends into the
southeast states with a northern stream trough sliding across the
Great Lakes region. A large portion of the area remains in a ThetaE
minimum with a pocket of drier air linger over the Southern
Appalachians. Much deeper tropical moisture resides along the
Coastal Plain with another swath of richer moisture pooled across
the Tennessee Valley. This will keep a rather muted response on
diurnal convection again today with coverage ranging from isolated
to widely scattered with the greatest rain chances across the
mountains were convection has already initiated along several high
elevation ridges. A few isolated storms will be possible farther
east, but confidence is a good bit lower. The pattern changes
tomorrow as the previously mentioned trough slides across the Ohio
Valley and helps to draw a plume of deeper moisture into the area
with PWATs surging to 1.5-2" across the area. Weak height falls
overspreading the region ahead of the trough axis in concert with a
very warm and moist airmass will foster a much better environment
for diurnal convection. Numerous to widespread thunderstorms are
expected across much of the area, especially northeast of the
Savannah River Valley. This will help keep temperatures a few
degrees cooler, but at the expense of a noticeably more humid
airmass. As with any summer thunderstorms, a few strong to isolated
severe storms with wet microbursts cannot be ruled out, but meager
lapse rates and poor DCAPE will generally preclude a greater threat
for organized damaging wind. Storms will also produce very efficient
heavy rain with isolated pockets of 1-3" in short amount of time
possible. This may lead to several instances of nuisance/minor
flooding of low-lying and poor drainage areas, especially along and
east of I-77 closer to the main plume of deep moisture. Should this
type of rainfall occur over an urban area, such as the Charlotte
metro, isolated flash flooding will be possible. Given the isolated
nature of locally heavy rainfall and uncertainty as to where it
would occur, will hold off on any hydro headlines at this time.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of noon Tue: Cyclonic flow continues over the eastern US through
the short term period as deep shortwave moves across Ontario/Quebec.
Sufficient shear and forcing is expected to allow diurnally
initiated convection to continue through Wednesday evening, so
PoPs diminish only slowly at that time.  Model consensus suggests
an embedded, more compact shortwave will move across the mid-MS
Valley Thursday and be invof the southern Appalachians Friday.
This feature may be enhanced by diurnal convection upstream of our
area, and accordingly there is spread among models as to where
it will be located Friday. Regardless the upper pattern should
be more favorable for diurnal convection than what we typically
see this time of year. Following multiple days of SW flow ahead
of the trough axis, PWATs will be above normal (+1.2 to +1.5 SD),
generally a bit higher Thu compared to Fri as the main trough axis
shifts east a bit.  Altogether this results in PoPs in the likely
to categorical range each day, once again being higher Thursday.

0-6km shear is shown to increase ahead of the compact shortwave,
perhaps exceeding 30 kt Thursday or Thursday night. There appears
the possibility of an organized band of convection developing with
the wave late Thursday in our western CWA, which might result in
a damaging wind threat more widespread than from typical summer
pulse storms; that said, moist profiles that day may limit cold pool
formation and mitigate that threat to some degree. Despite the deep
layer shear, flow will be unidirectional and Corfidi vectors short,
so training or backbuilding may occur. Combined with the PWATs,
an above-average threat of localized torrential rainfall and flash
flooding will persist.

Max temps will be near normal and heat index will remain below
advisory criteria.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 1245 PM Tue: Axis of the Canadian trough will be east of the
area Friday night and 500mb heights slowly rise thru the weekend.
That results in a gradual warming trend, with daily max temps
a few degrees above normal for Sunday and Monday. Heat index
accordingly will rise closer to, but not quite reaching, Heat
Advisory criteria in parts of our Piedmont southeast of I-85. With
respect to convection, while we may lose the enhancing effect
of the trough, ensemble CAPE and CIN don`t change much Sat-Mon
afternoons compared to Friday. Furthermore most deterministic runs
and ensemble members depict another trough in the Midwest circa
Sunday, suggesting a front will approach the CWA from the west
by Monday. There is however spread as to the advancement of any
front east of the Appalachians between the GEFS and EC Ensemble,
keeping confidence low.  For now, it seems reasonable to expect only
a small decline in daily PoPs for this period, still warranting
likely values for the mountains each afternoon and a solid chance
(30-45%) for the Piedmont.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Predominately VFR conditions will prevail at
all terminals through most of the period. The main concern will be
afternoon and evening thunderstorms both today and tomorrow.
Coverage today is expected to remain isolated to widely scattered
with the greatest chance for storms across the mountains at KAVL,
although a stray storm cannot be ruled out at any given location.
Valley fog will be possible again overnight, but confidence as to
whether any restrictions will impact KAVL remains low. Coverage of
afternoon storms is expected to be noticeably higher tomorrow with
impacts possible at all terminals. As with any storms, brief
reductions in visibility and ceiling can be expected.

Outlook: Typical summertime weather is expected into the weekend,
with scattered to numerous thunderstorms mainly in the
afternoon/evening and fog and/or low stratus possible each morning.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...TW
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...TW