483
FXUS62 KGSP 150600
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
200 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 130 AM Tue: Shortwave moving off the Mid-Atlantic coast
this morning is associated with a weak frontal boundary, really
just a convergence axis this far south. That feature is arguably
responsible for the isolated showers/storms now near the I-85
corridor of NC. Further progression of the boundary still looks
to be halted by upper disturbance lifting out of the Ozarks and
into the Midwest. 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; it is not clear whether this is along the stalled
boundary or along the sea breeze, 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, declining 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.

&&

.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 /06Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: A few SHRA/TSRA are still ongoing at
issuance time along an axis across the NC/SC Piedmont, just NW of
KCLT. Operational impacts appear generally unlikely aside from VRB
winds and low VFR stratocu, so only VCSH is mentioned. The same
axis looks to have passed the SC sites and thus convection is not
mentioned anywhere else early this morning. No reason to deviate
from previous expectations at KAVL or KHKY as far as river/valley
fog near daybreak. Developing S to SE flow in low levels stands
some chance of bringing low stratus to KCLT this morning, with
low MVFR thus mentioned in a TEMPO there. 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 SE sfc flow should help the sea breeze
push inland and hi-res models suggest convection will fire along
that boundary, and/or where outflows from the mtn storms collide
with the sea breeze. Hence prevailing SHRA at KAVL with PROB30
for TSRA during the usual 18/24 timing there, and PROB30 later
in the aftn/evening elsewhere. Valley fog possible again at KAVL
after 06z tonight, particularly given likelihood of precip this
aftn. Elsewhere low stratus may form early Wed morning on the
moist SE 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