623
FXUS62 KGSP 300533
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
133 AM EDT Sun Aug 30 2026

.WHAT HAS CHANGED...
Sunday`s PoP and dewpoint forecasts were updated based on recent
real-time data on the position of a diffuse frontal boundary.

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

&&

.KEY MESSAGES...
1. Diurnal showers develop again on Sunday and Monday across the
NC mountains, but coverage should be isolated to nonexistent the
rest of the week.
2. Hot and humid weather returns by Tuesday, with dangerous
heat index values expected over the low terrain each afternoon
this week.

&&

.DISCUSSION...
Key message 1: Diurnal showers develop again on Sunday and Monday
across the NC mountains, but coverage should be isolated to
nonexistent the rest of the week.

Not much change to the large-scale setup tonight.  Recent water
vapor imagery depicts a shortwave axis located southeast of I-85,
with synoptic-scale lift maximized east of the forecast area.
At the surface, a diffuse quasi-stationary boundary remains
draped across the southeastern tier of the forecast area...and
most stations are reporting some flavor of weak easterly flow,
resulting in weak isentropic ascent over the boundary.  Radar is
mostly clear, but a few isolated, elevated showers continue to
pop up all over the forecast area in response to the upglide.

Convection appears likely to remain suppressed and isolated the
next few days.  Can`t rule out some continuing elevated showers the
first part of tonight; a rumble of thunder can`t be entirely ruled
out, but elevated instability looks anemic at best, with a nearly
isothermal layer above 700mb where weak subsidence develops behind
the shortwave.  Don`t expect conditions to get too much better
during the daylight hours Sunday; as the last of any lingering
cyclonic flow in the mid-levels retreats northward, upper flow
will slacken.  So despite moist southerly flow in the low-levels,
and surface-based instability to the tune of 1000-1500 J/kg during
the afternoon...the lack of large-scale ascent or any discernible
triggering mechanism will keep showers and thunderstorms confined to
the ridgetops of the NC Blue Ridge, and likely non-severe in nature.

Subtropical ridging is expected to intensify through most of the
new workweek.  Thus, still think that the environment will become
increasingly hostile to convection.  Another round of isolated
mountain showers may take place Monday afternoon...beyond which
it`s looking unlikely that ANY convection will be able to develop
the rest of the week.


Key message 2: Hot and humid weather returns by Tuesday, with
dangerous heat index values expected over the low terrain each
afternoon this week.

Subtropical ridging is still expected to become re-established
across the Southeast U.S. by Monday, with deepening anticyclonic
flow aloft depicted in virtually all global ensembles by Monday
or Tuesday...centered over the Ozarks but extending well into the
Tennessee and Mississippi Valleys.  As a result, forecast profiles
depict stout subsidence aloft and dramatically increasing heights
over our area, with little evolution of the synoptic pattern
through the end of the seven-day forecast.

Triple digit heat index values are thus likely to return to the
low terrain each afternoon for most of the week.  The current temp
and dewpoint forecast supports isolate 100+ degree heat index,
mainly south of I-85, on Monday, with more widespread triple digits
on Tuesday and beyond.  By the second half of the week, still
think some zones could be under the gun for Heat Advisories...but
confidence of course remains limited at this time.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Tonight`s aviation forecast should again be
dictated by the weak frontal boundary draped across the area and
associated low-level moisture in place.  Most sites are currently
VFR, though a few MVFR ceilings have already begun to develop
along the I-77 corridor and parts of the NC mountain valleys.
Think that conditions will gradually deteriorate for most of
tonight, especially across the NC Piedmont and parts of the
Upstate...where LIFR (or intermittently worse) can be expected
around daybreak. Most guidance depicts a bank of low stratus
expanding across the area beginning around 09-10Z.

Conditional upon the more widespread coverage of fog and stratus
Sunday morning, restrictions may lift more slowly than they have
the last two days...with cloud bases gradually lifting from IFR to
MVFR and finally back to low-end VFR through mid- to late-morning.
Convection should be extremely isolated Sunday afternoon - likely
confined to the mountains, with too little coverage to justify so
much as VC precipitation in the KAVL TAF.  Another round of MVFR
to IFR stratus may develop again on Sunday night.

Outlook: Isolated mountain showers and thunderstorms may develop
again on Monday afternoon.  Drier weather is 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