483
FXUS62 KGSP 121839
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
239 PM EDT Sun May 12 2024

.SYNOPSIS...
As low pressures approach from the west, moisture increases to start
the week and rain returns to our area Monday afternoon and evening.
Rain and thunder are expected on Tuesday and Wednesday, followed by
a brief period of dry conditions on Thursday. Another low
pressure arrives for next weekend bringing more rain.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 225 PM: Ridge axis now situated over the lower MS Valley with
attendant sfc high extending over the Cumberland Plateau. These
features will build east tonight, and sfc winds will come around
to the NE across the Piedmont. Sfc/upper low in the Plains will
activate warm front to our southwest overnight, but it looks
pretty unlikely any of that precip will develop into our area
in the morning. PoP onset has been delayed compared to previous
fcsts, with dry air to overcome and the lift being relatively
weak. Midlevel clouds however will increase in numbers overnight,
but slow enough that decent radiational cooling still should occur,
so still went with bias-corrected guidance blend similar to what
has worked well in recent nights. Of particular note, the pattern
still may permit eventual development of in-situ CAD but see no
need to expect that will begin tonight, without precip.

Warm front will shift northward over the sfc high in the morning,
possibly resulting in light precip developing near the Blue Ridge
Escarpment and in NE GA by noon. Abundant alto/cirrus cloud
cover will be in place but low clouds are appreciably slower
to develop. Guidance mostly holds off with QPF until after 18z,
with saturation occurring from the top down. Still favor precip
chances no better than chance range for the majority of the CWA,
the exception in the Escarpment/GA areas where saturation appears
to occur earliest; those areas see likely PoP mention by late
afternoon. Thus, formation of CAD probably will not be until after
peak heating, but the cloud cover will impact highs especially SW
of I-26 where they should be in place more or less all day. Lack of
CAD also suggested by model consensus for winds going southerly
across the CWA by late morning. We end up with highs several
degrees below climo in the SW, but near or slightly above normal
in the sunnier NE. Any convection afforded by the upglide likely
will be too shallow to result in thunder.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 100 PM EDT Sunday: We remain on track for the likihood of
dreary sensible wx conds Monday night as a period of moist llvl
upglide flow expands atop of wedge-like pattern.  Widespread low
overcast, rain, drizzle and fog is on tap. Energy rounding the base
of potent Ohio Valley upper low will eject NE into the region on
Tuesday.  Along with an associated slug of deeper moisture, showers
are expected to be widespread.  It remains probable that the wedge
front, present along the SE fringes of the cwfa to start off the
day, will be able to erode, probably uncovering a small amount of
positive SBCAPE values SE of I-85 Tuesday afternoon. Within the
robust deep shear there remains the possibility of svr tstm
development along and SE of retreating/dissipating wedge front into
Tuesday evening.   The cwfa is progged to be within a cleaner warm
sector environment on Wednesday, all beneath cyclonically curved
flow aloft thanks to the lingering, but departing upper low axis. As
temperatures warm to seasonable mid-May levels, the atmosphere will
becoming moderately unstable.  Coverage of diurnally enhanced tstms
should becoming numerous, especially in Western NC where the flow
and forcing will be greater.  There should exist enough shear to
promote a few severe storms.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 200 PM EDT Sunday: Save for the small chance for isolated
ridgetop forced showers, we are expecting an essentially suppressed
atmosphere on Thursday as upper ridge axis translates atop the SE
CONUS.  Lower elevations will warm into the lower 80s.  The next
slug of southern stream deeper moisture and energy remains progged
to quickly advect into the cwfa on Friday.  The latest medium range
guidance is in decent enough agree with respect to the mass fields
on Friday with considerable convective response, so the inherited
sensible wx featuring numerous diurnally enhanced thunderstorms will
remain as is. Less than usual confidence exists regarding the
specifics for next weekend but with the wavy pattern likely to
linger along with spokes of southern stream energy rippling
eastward, above climo pops will be featured each day.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Initially sparse cirrus will slowly become
more widespread late this afternoon and overnight, with bases
lowering AOB 180 from SW to NE. Near W winds to start, except at
KAVL which should stay NW to NNW; KCLT should remain mostly on
the N side but occasional WSW obs are possible this aftn. High
pressure pushes east of the Appalachians allowing mainly NE
winds tonight, which should all turn SE in the morning. Onset of
warm upglide over sfc high will bring cloud bases to low VFR as
soon as daybreak at KAVL, elsewhere after 18z Mon. The upglide
could lead to in-situ cold-air damming with onset of any precip,
which is not likely enough to mention with best chance after the
respective TAF periods, but once the onset does occur MVFR cigs
could develop very quickly and persist into Tue.

Outlook: Widespread precip and restrictions developing Mon night,
with scattered thunderstorms developing Tue and Wed afternoons
bringing a chance for periodic restrictions. Some nocturnal
restrictions remain possible Tue and Wed nights. Brief drying
expected Thursday.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...Wimberley
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...Wimberley