130
FXUS62 KGSP 212344
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
744 PM EDT Mon Jul 21 2025

.SYNOPSIS...
A weak cold front will slowly cross the area late tonight into
Tuesday, increasing chances for showers and thunderstorms.
High temperatures and diurnal rainfall chances will be closer to
normal behind the front through Thursday, as high pressure builds
in from the northeast.  The heat and humidity will increase into
this weekend as southerly flow returns to the area.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 740 PM Monday: With a weak ridge of high pressure progged to
build swwd into the cwfa on Tuesday along with the corresponding
wind shift to NE, the pocket of above climo high temperatures is
forecast to shrink to the Savannah River valley and points south
and southwest.  Even within this region, maximums should remain in
the lower 90s with isolated locales reaching apparent temperatures
in the low 100s. Thus, no Heat Advisory will be issued at this
time. Isolated showers and thunderstorms continue across the area
this evening, and should continue to bubble for another hour or
two before mostly dissipating by late evening. A few strong wind
gusts remain possible this evening, but the threat of severe storms
is virtually nil. Convection will have the potential to become
numerous Tuesday afternoon as a broad llvl convergence zone sets
up within the ENE llvl flow.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 145 PM EDT Monday: Wednesday into Thursday, surface high
pressure will gradually propagate east into the western Atlantic as
an anticyclone over the Lower Mississippi River Valley expands east.
The pattern should afford us at least one relatively pleasant day
on Wednesday under northeasterly to northerly flow with dewpoints
in the lower to mid-60s and near-normal high temperatures.  As is
typically the case in this regime, the drier and more stable airmass
within the high-pressure ridge will limit PoPs across the Carolina
Piedmont, generally decreasing from slight near the Savannah River
to near-zero in North Carolina.  Near-climo PoPs are currently
forecasted across the mountains, where terrain-inflenced forcing
will influence coverage, as well as NE GA. where the airmass will
be a bit warmer and more humid thanks to an easterly fetch from
the Atlantic on the periphery of the anticyclonic flow.

By Thursday, flow will have veered southeasterly as meager height
falls occur over the middle Mississippi River Valley and the
upper-level anticyclone shifts to the Southeast coast.  This will
allow the briefly suppressed subtropical airmass to encroach upon
the area once again, resulting in a 1-2 degree uptick in high
temperatures and dewpoints closer to 70.  However, the proximity
of the deep-layer anticyclone will result in a warm column with
relatively poor lapse rates as well as a modest inversion between
700-750mb.  Therefore, this airmass will likely inhibit some
convection on Thursday.  As a result, forecast PoPs are closer
to climo (i.e., chance) across the area.  Nevertheless, given the
low-level moisture advection, resulting in PWs near if not slightly
above 2", and the weak unidirectional flow through the column,
any storms that do develop may result in locally heavy rainfall.
Weaker updrafts may limit the ability of any storm to last long
enough to result in excessive rainfall, but one or two cells could
still pose a nuisance flood threat.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 145 PM EDT Monday: By Friday, heat and humidity will be in
full force once again across the area as low-level tropical flow
takes a circuitous route from the Bahamas, around the anticyclone
off the Southeast coast, and into our region.  Our area will be
underneath a weakness aloft with a second anticyclone over the
Southern Plains, as a train of shortwaves continue to impact the
Ohio Valley and Mid-Atlantic regions.  The column will continue
to be warm with poor lapse rates and unimpressive SBCAPE values,
but continued orographic enhancement and weak upslope flow should
sustain scattered to numerous shower and storm coverage over
the mountains.  Increased moisture throughout the column and
potentially greater coverage with little change in storm-motion
characteristics suggests a somewhat higher excessive rainfall
threat compared to Thursday.  Highs will be 2-4 degrees above
normal with lower 70 dewpoints possible absent appreciable mixing.

Hot and humid conditions will persist into the weekend as a
shortwave trough approaches from the Ohio Valley.  Its proximity
should enhance forcing and shower/storm coverage across the
mountains, although bulk-shear and the overall warm and moist
profile continues to suggest isolated excessive rainfall will be
the primary threat.  Dewpoints are expected to creep higher still
and absent needed mixing; therefore, heat indices may once again
become a concern with values in the low 100s across the Piedmont
a possibility.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Isolated-to-widely scattered convection
lingers across the Terminal Forecast Area this evening. Activity
should continue to bubble for another hour or two before diminishing
further. Nevertheless, the probability of a cell passing near a
terminal is low enough such that no mention is warranted in the
TAFs for the remainder of the evening. Otherwise, VFR conditions
are forecast to prevail at the main TAF sites through the
period. Mountain valley fog/low stratus will again develop after
midnight, but is forecast to be mainly confined to the valleys
closer W and N of KAVL...as the near-surface air is a bit drier
there than it`s been for the past few days. Winds are expected to
settle at light NE at most sites overnight...continuing through the
end of the period, although speeds may increase closer to 10 kts at
the Piedmont sites Tue afternoon. As a weak front slides SW across
the area on Tue, at least scattered convection is expected across
much of the area, and at least Prob30s for TSRA are warranted at
all sites.

Outlook: Coverage of afternoon/evening convection is expected
to be more isolated/widely scattered in nature during the latter
half of the work week, with coverage likely increasing again over
the weekend. Low stratus and/or fog are possible each morning,
especially across the mountain valleys.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ018-026-028-
     029.
NC...Heat Advisory until 8 PM EDT this evening for NCZ070>072-082.
SC...Heat Advisory until 8 PM EDT this evening for SCZ008>014-019-
     104>109.

&&

$$

SYNOPSIS...JMP
NEAR TERM...CSH/JDL
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...JDL