986
FXUS62 KGSP 191049
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
649 AM EDT Sun May 19 2024

.SYNOPSIS...
A low pressure system will exit off the Carolina Coast today, with
high pressure building in from the north. Relatively dry conditions
return for the first half of the week resulting in only isolated
afternoon and evening showers and storms in the mountains. A cold
front will bring better shower and thunderstorm chances back into
the forecast late in the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 640 AM: Gradual height rises over the Northeast CONUS will
continue this morning, and a weak sfc high will build down the
East Coast. A backdoor front has moved through most of our CWA
as a result. A closed low is centered over GA embedded within
a shortwave which will slowly drift east into the Carolinas
today. Main precip remaining over the area is very light and
associated with deformation zone of the shortwave or via very
weak convection along the front itself. Updated PoPs to allow this
precip to slowly decay and focus increasingly south.

Beneath the shortwave, we retain pretty good lapse rates through
most of the daytime hours. The northeasterly flow associated with
the sfc high is deep and forcing really comes from the CAA, with
no appreciable warm upglide. A subsidence inversion will persist
over most of the Piedmont and should preclude new convection there
this afternoon. However, over the mountains, the inversion will
be weaker but also some degree of low-level convergence will be
present owing to slightly more backed flow behind the shortwave
meeting the easterly flow from the high. This should provide
slight forcing. Deep dry air in the mid to upper levels would
appear difficult for the relatively mild instability to overcome,
so PoPs have been limited to chance range in the mountains. Storms
likely will be slow moving but PWATs will be considerably lower than
what we saw overnight, somewhat mitigating heavy rain threat. With
the NE winds continuing, max temps will be several degrees below
normal despite partial sunshine. Remaining PoPs will diminish
nocturnally; some low stratus could develop near the Blue Ridge
Escarpment overnight in the wedgelike easterly flow. Mins will be
around normal.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 130 AM EDT Sunday: Subsidence from mid-level ridging should
keep most of the region capped Monday and Tuesday. The exception
will be the usual highest elevations of the NC mountains, which
may overcome the CIN and result in a few showers and possibly
an isolated garden-variety tstm during peak aftn heating. An
axis of dry sfc high pressure will set up along the East coast,
supporting mostly sunny skies both days. Highs will be near normal
on Monday (in the upper 70s to lower 80s in the mountain valleys
and the Piedmont), and slightly above normal Tuesday (mostly mid
80s). Patchy fog will be possible, especially in the mountain
valleys both Monday and Tuesday nights, with lows near to slightly
above normal.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 145 AM EDT Sunday: Upper ridging across the Southeast
and along the East Coast will begin to gradually break down,
as a series of shortwaves eject out of the Rockies. Wednesday
looks like the last dry day, with stronger capping resulting in no
mentionable PoPs and temps a few degrees above normal. From there,
a cold front is fcst to sag southeastward across the Ohio Valley
and bring a return of mainly diurnal convection to the area. Most
activity will be in the northern part of the forecast area Thursday
as the front approaches, but then expands south for Friday. A
pronounced shortwave trough crosses the area Friday, which may
enhance convective coverage and contribute to bulk shear. But
the 00z deterministic guidance is still not in great agreement
on placement of the front and resulting QPF response. The ECMWF
still is a little north of the area Friday compared to the GFS and
Canadian. Overall, a more active convective pattern is expected
to continue from Friday thru the weekend. Temps will continue to
be slightly above normal thru the end of the medium range.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Backdoor front pushed south of the terminal
area overnight leaving NE winds in place for the period. Low-end
gusts are really not out of the question any time thru sunset. Cigs
are proving somewhat variable but low MVFR to IFR will be common
through late morning. Light precip ongoing near KGSP/KGMU/KCLT
may provide enough downward motion to scatter the low decks and
allow for periodic improvement. Expect that enough sfc warming
will occur by 15-17z to eliminate the IFR, but with subsidence
inversion persisting bases may not lift above MVFR level in spots,
but scattering still expected by early aftn. Low stratus could
creep in from the NE tonight but confidence only moderate, so will
keep cloud mention SCT near daybreak Mon.

Additional note for KAVL: Weak low-level convergence will persist
over the Appalachians today along with weak instability, so a
TEMPO is retained for chance of isolated or widely sct TSRA this
aftn. Winds are expected to flip to SE this evening.

Outlook: Stronger high pressure settles over the region Monday
and persists through midweek, but isolated mountaintop convection
still appears possible both Monday and Tuesday afternoons. Precip
and restrictions possible with next front arriving circa Friday.

&&

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

&&

$$

SYNOPSIS...ARK
NEAR TERM...Wimberley
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...Wimberley