354
FXUS62 KGSP 151101
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
701 AM EDT Tue Jul 15 2025

.SYNOPSIS...
A typically active mid-summer week is ahead as daily thunderstorm
chances continue. A few storms could produce damaging wind gusts and
localized flash flooding. Daily high temperatures will trend back to
around the normal mid-July mugginess through Thursday. Continued
daily thunderstorms chances and slightly warmer temperatures in
store for the upcoming weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM Tue: Shortwave moving off the Mid-Atlantic coast
this morning is associated with a convergence zone extending down
I-85 thru NC and perhaps the eastern Upstate. Isolated convection
basically bubbled along this boundary all night but for now activity
within our CWA has diminished. Even as the shortwave loses influence
in our area, progression of the convergence zone looks to be halted
by upper disturbance lifting out of the Ozarks and into the Midwest;
it remains difficult to tell if lee troughing may also help to
reinforce said convergence. Meanwhile, low pressure near Florida
will drift west today, resulting in slightly lower heights and
somewhat cooler high temperatures than the past few days. The low
should reinforce southeasterly low-level flow, keeping dewpoints
quite muggy and promoting inland movement of the sea breeze.

CAMs depict ridgetop convective initiation more or less at the
usual early afternoon time. Steering flow is weak but above
850mb generally out of the W to NW, so slow propagation into the
Piedmont would appear likely. Most runs show a secondary area of
initiation later in the day near the Piedmont trough, but far
enough from the mountains that those storms` outflows are not
necessarily responsible, at least initially. PoPs remain elevated
into the evening in the mid to upper portions of the Piedmont,
possibly being buoyed by the sea breeze moving inland and declining
only slowly overnight. It looks like a setup where it is hard to
completely rule out a surprise isolated storm redeveloping at any
point overnight, at least ahead of the sea breeze. Sfc-midlevel
delta-theta-e values are not especially favorable for microburst
winds so the threat of severe wx probably will be highly isolated at
most. PWATs will remain near 2 inches. Storms will be slow-moving
and a threat of localized flash flooding will exist; even though
the sea breeze could make MBE vectors longer (less potential for
training or stationary storms) the orientation of the upper flow
may be opposite to the sea breeze in some locations, so hydrologic
concerns may not totally diminish, particularly in areas that saw
heavy rain in the past 2 days.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 105 AM EDT Tuesday: Relatively flat flow aloft through much of
the short term period, while the flow runs southerly with the
presence of a Bermuda high. Hot and humid conditions won`t slow
down, especially given a potential tropical disturbance moving over
the Gulf. Expect reinforced tropical moisture to move into the
southeastern CONUS as a result during the middle part of the week.
In this case, convective coverage may blossom more than the typical
diurnal summertime trend. Heat index values will flirt with Advisory
level criteria with higher than normal dewpoints and very warm
thicknesses in place both Wednesday and Thursday afternoons. Ambient
temperatures overall remain at or slightly above normal through the
forecast period with little change in the overall pattern.
Thunderstorms that develop will still pose a wet microburst and
flash flood threat across the CFWA.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 125 AM EDT Tuesday: Higher heights gradually shift over the
southeastern CONUS by the end of the workweek into the weekend as
the upper ridge offshore retrogrades. This will rise temperatures
a few degrees to go along with lingering tropical moisture, keeping
dewpoints elevated above normal. There is a good chance for heat
index values reaching Advisory criteria, especially in the Piedmont
zones. The synoptic pattern keeps a baroclinic zone just north
of the CFWA, while the potential tropical system makes landfall
somewhere over the Central Gulf Coast at the beginning portions
of the forecast period. The leftover tropical moisture is shown
getting engulfed by the baroclinic zone and will uptick PWAT values
closer to ~2.00" for the weekend. Daily diurnal convection will
remain above normal for mid-July as a result and should slightly
enhance the risk for localized flash flooding and wet microbursts
through D7 despite very warm air aloft.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: A few SHRA/TSRA are ongoing at issuance
time invof a weak trough in the NC Piedmont. Direct impacts to TAF
sites are not expected this morning, aside from some lingering
MVFR level clouds near KCLT. Stratus deck near KHKY but appears
transient per satellite and is likely to scatter by 12z.

Otherwise, diurnal cu should develop by late morning and sfc winds
come up from the S to SE. SHRA/TSRA are expected to break out
over the mountains near peak heating and propagate slowly SE`wd
with weak westerly upper level steering flow. The aforementioned
Piedmont trough appears to persist and serve to focus development
again. Hence prevailing SHRA at KAVL with PROB30 for TSRA during
the usual 18/24 timing there, and PROB30 later in the aftn/evening
elsewhere. The SE sfc flow should help the sea breeze push inland
by evening which may additionally enhance or prolong convective
activity well after sunset, but confidence is low given that
some areas may be worked over by earlier rounds of convection.
Valley fog possible again at KAVL after 06z tonight, particularly
given likelihood of precip this aftn. Elsewhere low stratus is
expected to form via radiation and/or the moist onshore flow.

Outlook: Typical summertime weather is expected this week with
scattered to numerous thunderstorms each afternoon/evening. Fog
and/or low stratus are possible each morning in mountain/river
valleys, and conditions look favorable for stratus to expand inland
from the Atlantic coast each morning as well.

&&

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

&&

$$

SYNOPSIS...CAC
NEAR TERM...Wimberley
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...Wimberley