421
FXUS62 KGSP 181758
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
158 PM EDT Tue Aug 18 2026

.WHAT HAS CHANGED...
No significant changes to overall thinking. Key Message 2 will
be further revised by 3 PM EDT.

&&

.KEY MESSAGES...
1. Relatively quiet weather will continue through Wednesday, with
very low chances for afternoon showers and thunderstorms. Hot
and muggy conditions will persist.
2. Afternoon showers and thunderstorms return Thursday and
persist through the weekend. A cold front may further enhance
storm activity over the weekend.

&&

.DISCUSSION...
Key message 1: Relatively quiet weather will continue through
Wednesday, with very low chances for afternoon showers and
thunderstorms. Hot and muggy conditions will persist.

Our region will remain under weakly cyclonic upper flow through
the midweek period. Temperatures and dewpoints are running slightly
lower this afternoon than they were on Monday, keeping heat index
out of Heat Advisory range. That said, it will remain muggy even
for August. A weak capping layer remains above the PBL, and the
lower temps/dewpoints also should have the effect of inhibiting
deep convection over the area this afternoon. With abundant cumulus
however a stray/brief shower is not out of the question in the lee
of the Blue Ridge Escarpment, although the overall chance is only
about 10%. Generally northerly low-level flow will continue into
Wednesday which may bring dewpoints slightly lower still. Thus the
coverage of afternoon cumulus is expected to be a little lower
and PoPs remain near zero, and the afternoon may feel slightly
less oppressive.


Key message 2: Afternoon showers and thunderstorms return Thursday
and persist through the weekend.  A cold front may further enhance
storm activity over the weekend.

By Thursday, another weak boundary associated with an h50 shortwave
crossing the Mid-Atlantic will settle across the Tennessee Valley.
Though guidance doesn`t depict an actual frontal passage through the
end of the week, the environment across the western Carolinas should
become moist and unstable enough to support a return to diurnal
convection on Thursday and Friday.  It`s not even entirely out of
the question that a decaying MCS originating on the frontal boundary
could slide across the area, though the upper pattern isn`t as
favorable for such a system to move into our area versus locations
farther north.  Regardless, even if we only see seasonally-typical
diurnal convection, profiles depict enough DCAPE to support a
couple of strong to severe storms producing wet downbursts.

By Friday, and certainly by Saturday, the approaching front and
strengthening upper flow will allow deep layer shear to increase,
and we`ll begin to see the potential for more organized convection
to develop, until the front crosses the area over the weekend.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Abundant low VFR cumulus this afternoon with
light NW winds. Cumulus should dissipate by sunset leaving mostly
SKC though FEW cirrus occasionally may be seen overnight. Winds
remain light but veer to NE at all sites except KAVL. With expected
good radiational cooling, valley fog appears likely enough to
include TEMPO IFR at KAVL in the morning. Less coverage of cumulus
expected Wed, with bases also more likely to remain at/above FL045
at KCLT.

Outlook: Scattered afternoon/evening convection Thursday through
Saturday. Low stratus and fog will be possible each morning,
especially in the mountain valleys.

&&

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

&&

$$

JCW/MPR