996
FXUS62 KGSP 262332
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
732 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 725 PM EDT Thursday: Most of the showers and thunderstorms
from earlier in the afternoon has quickly dissipated with the loss
of peak heating and overturned atmosphere. Still a few storms worth
keeping an eye on along and east of the I-77 corridor where the
atmosphere is somewhat left untapped. Can`t ruled out areas of
stratiform precip lingering through the evening hours in the
southwest mountains, northern Upper Savannah Valley, and east of I-
77. Otherwise, the forecast remains on track with only minor tweaks
made based on current observations and latest radar/satellite trends.

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.

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 /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: VFR conditions will prevail through most
of the forecast period. Most of the showers and thunderstorms
from this afternoon have dissipated and moved far enough away
from the terminals to take out any thunderstorm mention through
the rest of the evening and overnight tonight. Kept a mention
of lingering VFR convective debris through tonight, but likely
scatters out completely by the early morning hours Friday. 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