082
FXUS62 KGSP 270245
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1045 PM EDT Thu Jun 26 2025

.SYNOPSIS...
The upper ridge which was responsible for the very hot weather we
have had will gradually weaken, allowing temperatures to get closer
to normal through the weekend. A disturbance meandering over the
Deep South will help produce mainly afternoon and evening showers
and thunderstorms each day.  A weak cold front reaches our region by
Tuesday and becomes stationary west to east through mid week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 1035 PM EDT Thursday: All precip has ended across the area,
while the convective debris has quickly shifted out of the CFWA as
well. Starting to see signs of ground fog in areas that received
heavy rainfall from early, but remains isolated. Made only minor
tweaks to the forecast based on current observations and latest
trends. Enjoy a nice late June evening.

A flat upper ridge extends from the Tennessee Valley to the Mid-
Atlantic with a weakening upper low associated with a Tropical Upper
Tropospheric Trough centered over Florida. This helped set up a
period of scattered diurnal convection, but the environment lacked
compared to Wednesday as it had to overcome a very overturned
atmosphere. Otherwise, valley fog will once again be possible,
especially across the Little Tennessee Valley early Friday morning.
A more seasonable summertime pattern returns tomorrow with "cooler"
highs in the upper 80s to low 90s and heat indices well below
advisory criteria, although a few readings in the low 100s cannot be
ruled out. Another batch of diurnally driven thunderstorms is once
again expected with the greatest coverage over the mountains again.
Coverage east of the mountains remains uncertain, especially east of
I-85. As is the case with any summer storms, a few wet microbursts
cannot be discounted but the environment will remain on the lower
end for microburst potential.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 240 PM EDT Thursday: The pattern will remain unsettled with
showers and storms expected again Saturday and Sunday. Coverage
should be enhanced with an upper diffluent pattern in between a weak
upper low near FL and a flat trough over the Great Lakes. The
typical mountaintop and lee trough convergence will be the triggers
for convective initiation, and shear and thermal profiles will
support a pulse storm mode. The NBM has categorical PoPs in the
mountains tapering to likely in the Foothills and high-end chc
southeast of I-85. This seems a little high, but over a 12-hour
period, coverage may largely verify these values. A few strong wet
microbursts are possible both days from mid aftn to early evening.
Also, weak steering flow and elevated PWs will yield an
isolated/localized heavy rain/flood threat. Temps will continue to
be slightly above normal. Dewpts mix out a little both days, but
heat indices max out around 100 and possibly higher in the southern
Upper Savannah Valley and the Charlotte area. Not expecting to need
a Heat Advisory either day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 250 PM EDT Thursday: A weak upper low will open up into a
relative weakness in the subtropical ridge over FL/GA Monday, while
a northern stream trough digs into the Great Lakes and Ohio Valley.
This set up should keep enhanced diurnal convection going thru the
first half of next week. In fact, the deterministic guidance shows
even more convective response Monday and Tuesday than what we`re
expecting in the previous days. The digging trough will bring a weak
cold front SE toward the forecast area and may provide extra
convergence for convection Tuesday. Pretty much every day has
similar PoPs and temps, with a slight uptick in PoPs and a slight
downward trend in max temps Tuesday. The above-climo PoPs may
increase excessive rain/flash flood threats as we continue with this
pattern. Severe threat should remain a few wet microbursts each day,
with perhaps an increase in more organized storms Tuesday thanks to
a little more shear and upper divergence associated with the digging
upper trough.

There is disagreement between the GFS and ECMWF on whether the cold
front will push far enough thru the forecast area to dry us out
and bring temps back to normal. The GFS hangs the front up across
the Piedmont, while the EC pushes it to the I-20 corridor. It`s
difficult for a front to clear thru the area this time of year,
and the EC seems to be on the more amplified side of the LREF
guidance on the 500 mb trough. That said, the guidance blend does
lower PoP into the chance range for Thursday.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions will prevail through most
of the forecast period. All of the showers and storms have moved out
of the area, including the convective debris. Some instances of
ground fog developing at a few locations that received heavy
rainfall, but coverage is isolated. Not expecting widespread low
stratus or fog except in the mountain valleys and placed a TEMPO
mention for 5SM and FEW007 at KAVL just before daybreak, but per
usual, this forecast is typically boom or bust. Another round of
afternoon showers and storms with associated restrictions are
expected Friday, so placed a PROB30 at all TAF sites. Welcome to
Summer.

Outlook: Daily chances for afternoon and evening showers and
thunderstorms continue into next week. Fog and/or low stratus will
be possible each morning in the usual mountain valleys as well as
near lakes and rivers.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...CAC/TW
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...CAC