426
FXUS62 KGSP 291033
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
633 AM EDT Sat Aug 29 2026

.WHAT HAS CHANGED...
No significant changes were made to the public forecast this
morning.

The aviation discussion was updated to reflect the impending 12Z
TAF issuance.

&&

.KEY MESSAGES...
1. Diurnal showers and thunderstorms continue each afternoon
through Monday, with increasingly sparse coverage expected
each day.
2. Hot and humid conditions return for the new workweek. Dangerous
heat index values arrive in the low terrain by the second half
of the week.

&&

.DISCUSSION...
Key message 1: Diurnal showers and thunderstorms continue each
afternoon through Monday, with increasingly sparse coverage expected
each day.

Little change in the pattern over the last 6 hours.  An ill-defined
quasi-stationary boundary remains sprawled across the region,
with extensive mid- and upper-level cloud cover east of I-26.
Patchy dense fog has developed, mainly in the NC mountain valleys,
over the last few hours, and areas of low stratus have developed
even outside the mountains.  In particular, a deck of low stratus
has begun to encroach on the I-77 corridor and parts of the
eastern Upstate.

CAMs are in good agreement that another round of diurnal convection
will initiate by early afternoon Saturday, but generally think
it`ll get less of a bump from the environment than the last couple
days and thus remain mostly confined to the high terrain. Heights
are already beginning to rise ever-so-slightly as the upper trough
retreats northward, and this trend should continue through the next
48 hours.  As a result, upper flow generally looks weaker, resulting
in less-impressive deep shear than the last two days. Still, the
NAMnest, RRFS, and ARW have joined forces to depict CI over the I-77
corridor and points east, on the moist side of the remnant boundary,
during the afternoon and early evening hours.  These zones will
destabilize to the tune of 1000-1500 J/kg sbCAPE...enough for a
few stronger storms, perhaps even a severe one.  Farther west,
the influence of a postfrontal inversion and weak subsidence
aloft should suppress convection.  Indeed, the most recent round
of 06Z CAMs featuring increasingly scant convection over most of
the area today.

There`s a case to be made for some warm-advective showers developing
late Saturday evening and persisting into the wee hours of Sunday
morning.  Deterministic models feature a weak shortwave sliding
along and north of I-40 during this period, and in response,
weak WAA should develop.  Forecast profiles feature little, if
any, elevated instability, so no expectations for severe weather
or even any thunder...but a round of overnight rainfall is well
within reason.

The environment will become increasingly inhospitable for deep
moist convection through the early part of next week.  As mid-level
troughiness continues to retreat northward, lapse rates will become
less and less impressive, while at the surface there should be no
triggering mechanism to be found.  Sunday and Monday, convection
should remain mostly or entirely confined to the ridges of the NC
mountains, and Tuesday and beyond even mountain showers should be
isolated at best.


Key message 2: Hot and humid conditions return for the new workweek.
Dangerous heat index values arrive in the low terrain by the second
half of the week.

By Monday, long-range ensembles are in good agreement that the
subtropical ridge will become re-established over the Southeastern
United States.  As heights build and a Bermuda High-like feature
sets up over the western Atlantic, the heat and humidity should
return in spades.  Notwithstanding the influence of dewpoint mixing,
which is difficult to capture effectively at long time ranges,
we expect upper 90s to triple digit heat index values to return by
Tuesday or Wednesday for much of the low terrain.  By the second
half of the week, we could be back in Heat Advisory territory,
though confidence is limited at this point.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Spotty and intermittent restrictions,
ranging from MVFR to VLIFR, have developed across the terminal
forecast area this morning, mostly as a result of patchy low
stratus.  An extensive deck of thick cirrus remains in place and
has prevented more widespread fog and stratus from developing east
of I-26.  Over the mountains, however, clearer skies have permitted
the development of more consistent valley fog and low stratus.
SCT MVFR-level clouds have developed along I-77 as well; guidance
has been keying on potential for pre-dawn MVFR to IFR ceilings.
It`s unclear whether actual ceilings will manage to develop,
particularly at CLT, but the cloud deck is there, and thus a TEMPO
remains in place at CLT for possible restrictions.

Whatever restrictions develop will scatter out quickly after
daybreak, giving way to a mainly VFR day.  Some ridgetop showers
and storms are expected to develop again, but far less coverage is
anticipated over the Piedmont and Upstate than we got on Friday.
Went ahead and pulled the PROB30s for afternoon convection at GSP,
GMU, and HKY entirely, leaving only AVL and CLT with mentionable
precip in the 12Z TAFs.  Winds will start out the day from the
NE, then toggle around to the SE by early afternoon.  For CLT,
guidance has trended later with the timing of the wind switch...in
the 17-20Z timeframe.

Outlook: Scattered diurnal showers and storms are expected through
Sunday, mostly over the mountains, then entirely over the mountains
by Monday.  Mountain valley fog and low stratus will be possible
each morning through the first part of next week.

&&

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

&&

$$

MPR