207
FXUS62 KGSP 211817
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
217 PM EDT Tue May 21 2024

.SYNOPSIS...
Warm high pressure will persist across the region through the
middle of the week with a few showers and storms possible each
afternoon over the mountains. Rain chances increase Thursday and
remain in the forecast each day through Tuesday.  Several weak waves
of low pressure will move from the lower Mississippi Valley to the
Carolinas.  Temperatures will remain above normal.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 155 PM EDT Tuesday: All quiet across the area as a potent
positively-tilted ridge extends from the western Gulf Coast all
the way into the Mid-Atlantic.  Despite the intrusion of a weak
wave into this upper pattern, there`s no evidence yet of any
convective towers going up over the NC mountains.  The latest
analysis puts some 500-1000 J/kg sbCAPE across the NC-TN border
counties, though, so eventually we should see at least some weak
showers start to develop.  Most of the CAMs depict at least some
widely scattered ridgetop convection ramping up over the next
2-3 hours.  Temperatures should climb into the mid-80s

Tonight, profiles will dry out as the wave translates east.
The mountains may experience some debris cloudiness even after
convection subsides, but will clear gradually after midnight as
the upper height gradient strengthens a bit, and residual moisture
is advected away.  A few hours of mountain stratus and valley fog
are depicted in most of the guidance, to clear out again quickly
after daybreak Wednesday.  Lows will drop to the lower 60s across
most of the area.  Another day of generally suppressed weather
is expected on Wednesday.  The lack of any discernible synoptic
triggering mechanism paired with lapse rates at least as poor as
today`s should preclude much, if any, convection from occurring;
instead, we can expect a dry and quiet day tomorrow.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 145 PM Tue: A series of short waves will cross the area in
generally westerly flow aloft. This will bring increasing chances of
mainly diurnal convection Thursday and Friday. That said, showers
may linger overnight, especially across the mountains. Instability
may rise into the moderate range Thursday, but a weakening warm nose
may linger keeping the better instability over the mountains, and
possibly into the I-85 corridor, especially if the forcing overcomes
the warm nose. Bulk shear will approach 50 knots, so a severe storm
or two will be possible if the instability and shear can overlap.
Temps will be around 5 degrees above normal.

Looks to be a better chance of realizing moderate sbCAPE Friday as
the warm nose appears to fully erode. Bulk shear drops back to
around 40 knots, but a few severe storms will be possible again
given the forcing and dCAPE values. Temps remain nearly steady.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 215 PM Tue: The active pattern continues as short waves move
through the generally westerly flow and across the area. With the
strongest wave moving in on Tuesday. This will least to continued
chances of diurnal convection, with lingering nocturnal showers as
weak surface features move through in association with the waves.
Too soon to tell if any of the days have a better severe storm
chance than the others, but they are possible. Also, heavy rainfall
chances will steadily increase as PW values increase with each wave.
Isolated flooding would be possible in areas that receive rounds of
heavy rainfall.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: VFR through the period for non-mountain
terminals, as upper ridging suppresses widespread convective
activity.  CAMs depict some isolated convection across the mountains
today, which like yesterday will be mainly showers.  Can`t rule
out some TS, but it`s looking isolated enough to forego mention
in even the KAVL TAF.  This was left a PROB30 as confidence still
isn`t great on initiation, which is lagging behind most of the
CAMs at this time (c. 1715z).  Tonight, some MVFR fog/ceilings are
expected in the major mountain valleys, with impacts only for KAVL.
More of the same tomorrow, with VFR conditions after daybreak and
isolated ridgetop convection in the afternoon..

Outlook: More numerous showers and thunderstorms, along with
associated flight restrictions, will return with a cold front
late Thursday into Friday. A more active pattern may persist into
the weekend.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...MPR
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...MPR