320
FXUS62 KGSP 261853
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
253 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 206 PM Thursday: 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. The
airmass over the western Carolinas and Georgia has been slow to
recover today following significant overturning during yesterdays
vigorous storms. ACARS soundings remain capped east of the mountains
with a dearth of cumulus across much of the area. The best portion
of the cumulus field is across northern Iredell into Davie county,
but even then the quality of the cumulus is sub-par at best. A few
cumulus have been trying to get going along the I-85 corridor in the
Upstate, but once again very unimpressive. The mountains are a
different story, however, where mechanical forcing has helped
develop scattered strong to severe storms already this afternoon. A
threat for isolated damaging winds and small hail will continue over
the mountains for the next several hours where moderate instability
has been able to develop. Confidence quickly wanes east of the
mountains owing to the previously mentioned lack of cumulus field.
An earlier outflow boundary pushing down the Hwy 321 corridor into
Hickory failed to initiate any new updrafts owing to the shallow
depth of the cold pool and rather high LFCs. The story is the same
across the Upstate where a previous boundary also failed to
instigate new convection. Regardless, a couple isolated to widely
storms may be able to get going later this afternoon into early this
evening as heating maximizes, but may also remain rather muted. The
environment isn`t anywhere near as favorable for severe storms today
compared to yesterday as the residual EML has pushed out of the area
with less impressive lapse rates and only modest instability. DCAPE
remains the most impressive parameter and any isolated deeper cores
that are able to develop could contain locally strong to damaging
winds.

Any storms should wane fairly quickly this evening with loss of
heating with a rather benign overnight period expected. Valley fog
will once again be possible, especially across the Little Tennessee
Valley. 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 /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions are ongoing at most terminals
early this afternoon but another round of afternoon showers and
thunderstorms is already underway. Temporary restrictions from
thunderstorms will be possible at KAVL and KHKY over the next
several hours. Activity may spread farther east through the rest of
the afternoon with restrictions possible along the I-85 terminals.
Any storms should dissipate this evening with loss of daytime
heating. VFR conditions will prevail overnight with the exception of
any patchy fog, especially in mountain valleys. Confidence is too
low to warrant mention in any TAFs at this point. Another batch of
afternoon storms will be possible again tomorrow.

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...Heat Advisory until 8 PM EDT this evening for NCZ036-037-057-
     071-072-082.
SC...None.

&&

$$

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