184
FXUS62 KGSP 310540
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
140 AM EDT Mon Aug 31 2026

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

The aviation forecast was updated to reflect the recent 06Z TAF
issuance.

&&

.KEY MESSAGES...
1. Heat and humidity will dominate the forecast for the next
week. Dangerous triple digit heat index values are expected across
much of the low terrain each afternoon.
2. Isolated ridgetop showers will be possible each afternoon
through the first half of the week. A thunderstorm or two may
be possible as well, but severe threat will be virtually non-
existent.

&&

.DISCUSSION...
Key message 1: Heat and humidity will dominate the forecast for the
next week.  Dangerous triple digit heat index values are expected
across much of the low terrain each afternoon.

00Z RAOBs and RAP analysis suggest that any lingering cyclonic flow
aloft has retreated north into the upper Mid-Atlantic tonight,
leaving extremely weak diffluent flow over the Carolinas, with
weak subsidence underway behind a shortwave trough axis now located
over the Carolina coastal plain.  A broad, 596dm upper anticyclone
centered over the Ozarks has become the dominant synoptic feature to
speak of, and should largely dictate the next several days` weather.

LREF ensemble members are in excellent agreement that anticyclonic
upper flow will slowly but steadily migrate eastward over the next
several days, becoming centered over the Carolinas and eastern
Tennessee Valley through the middle of this week.  In response,
increasingly potent subsidence will develop while low-level
thickness will skyrocket.  By Tuesday and certainly by Wednesday,
high temperatures will climb into the mid- to upper-90s east of the
mountains.  The dewpoint forecast is not much better, with forecast
values in the lower 70s each day...and based on forecast profiles,
quite limited prospects for afternoon dewpoint mixing to provide
relief.  Consequently, the forecast continues to feature low- to
mid- 100s heat index values each afternoon from Tuesday through
Friday, posing a risk of heat-related illness.  Heat Advisories
may be eventually needed for some zones as we get into the week.

There`s a growing signal in the long-range ensembles for a weak
cold frontal passage sometime from late Friday through early
Saturday.  Confidence is limited at this timescale, but such a
feature would likely advect lower dewpoints (if not especially
cooler temperatures) into the area, providing some measure of
relief from the heat by next weekend.  Can fall be here yet???


Key message 2: Isolated ridgetop showers will be possible each
afternoon through the first half of the week.  A thunderstorm or
two may be possible as well, but severe threat will be virtually
non- existent.

Persistent subtropical ridging through much of this week will hold
convection at bay for most of the area.  Hi-res guidance continues
to feature a paltry 700-1200 J/kg sbCAPE across the NC mountains on
Monday and Tuesday afternoons...but sans any synoptic-scale lift,
lapse rates look to remain quite poor, such that any developing
updrafts will struggle to gain much momentum (literally and
figuratively).  The CAMs are in decent agreement on isolated to
widely scattered showers developing across the Appalachians this
afternoon and again on Tuesday afternoon...with perhaps nominally
better coverage over the Smokies and Balsams.  As stated prior,
updrafts will be weak and anemic, so whether enough charge
separation can even develop to support thunder is...questionable.

The remainder of the week looks to remain similarly suppressed,
with limited coverage of showers even in the mountains.  The next
chance for better, more widespread rain and thunder would be,
at the earliest, on Friday, potentially as late as Saturday.
By this point, the subtropical ridge will start to deteriorate in
response to a deepening upper low somewhere over eastern Canada
(the location varies significantly in the 00Z suite of long-range
ensemble solutions).  A shortwave is progged to dive out of the
Midwest, tracking somewhere across the Mid-Atlantic or Carolinas
along the periphery of the upper low, and driving a modest
cold front across the Southeast.  At this point, the parameter
space varies widely from member to member...and realistically
the determining factor in how much, if any, severe or hydro
threat materializes will be the timing of the surface front.
So, with confidence in the frontal passage itself moderate at
best...confidence in impacts is low at this time.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Clear and dry everywhere tonight, with hints
of mountain valley fog starting to form already, with restrictions
already reported at AVL and 1A5, but VFR almost everywhere else
so far.  Another night of fog and low stratus is expected, mainly
in the mountain valleys, but with some potential over the I-77
corridor again as extremely weak easterly flow continues to advect
moisture into the area.  Confidence is decent that IFR to LIFR low
stratus will develop over the Piedmont and Sandhills...but whether
it makes it as far west as CLT is another story.  For now, have
kept mention of IFR non-ceilings, but could foresee a scenario
where we`ll need to amend in a mention of actual restrictions
later tonight.  The Upstate terminals and HKY look less likely to
see any actual meaningful restrictions tonight.

VFR conditions expected for Monday at all terminals.  Isolated
mountain convection is expected once again Monday afternoon, but
coverage looks too low to include a mention of any showers at AVL.
Weak ESE flow is expected in most terminals by late morning Monday.
Mostly clear conditions and light winds are expected Monday night,
with another round of mountain valley fog.

Outlook: Very isolated mountain showers and thunderstorms may
develop again on Tuesday afternoon.  Drier weather still likely to
return the rest of the week.  Fog and low stratus will be possible
each morning, especially in the mountain valleys.

&&

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

&&

$$

MPR