391
FXUS62 KGSP 300001
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
801 PM EDT Mon Apr 29 2024

.SYNOPSIS...
The warming trend will continue through mid week as high pressure
remains centered just off the Atlantic Coast. A weak cold front is
expected to move through the area on Tuesday bringing scattered
showers and thunderstorms. Another front is expected to approach
the Carolinas by this weekend and bring more showers and
thunderstorms to the area.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 600 PM EDT Monday: No major changes were needed this update as
the forecast remains on track. Otherwise, dry conditions persist
area-wide this afternoon with cumulus and cirrus confined to mainly
NE GA, the far SW NC mountains, and the western SC Upstate. Cumulus
should dissipate around sunset with the loss of daytime heating.
However, cirrus will thicken through this evening as a cold front
approaches out of the west.

An upper ridge will break down as it progresses off the East Coast
tonight, downstream of large scale height falls associated with a
series of short wave troughs moving east of the Miss Valley. One of
these waves is expected to evolve into a small upper low just west
of our area tomorrow morning as it catches up to the weakening
ridge. A weak cold front will accompany height falls into our
forecast area during the daylight hours Tuesday. Pre-frontal
convection could make a run toward far western NC by sunrise,
warranting chance PoPs for SHRA across those areas prior to 12Z.
PoPs ramp up from the west Tuesday as the frontal zone crosses the
area, mainly during the afternoon. A consensus of model guidance
indicates modest instability...sbCAPE of around 1000 J/kg to
interact with a rather weak frontal circulation. Nevertheless, with
the upper low poised to pass over the CWA during the afternoon...at
least solid chances PoPs appear warranted throughout the CWA, with
likelies advertised across much of the western 1/3 or so of the
area. Shear parameters are forecast to be unimpressive...around 30
kts of 0-6km bulk shear. Given the expected instability, the
potential for severe storms will be very low. Temps are expected to
be around 5 degrees above normal through the period.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 145 PM EDT Monday: By Tuesday evening showers will
be well underway as a vigorous shortwave pushes into the
Carolinas and attendant frontal boundary arrives from the west.
This boundary looks likely to slide entirely east of the area
by early Wednesday, giving way to a postfrontal regime for much
of the day.  The resultant CAA won`t be especially strong, and
so winds aren`t expected to be an issue, even in the mountains,
and temps won`t see much of a dent.  In fact, temperatures will
largely be moderated by better solar insolation than Tuesday`s and
by rapidly-increasing thickness as potent ridging fills in...and
so highs Wednesday afternoon should climb into the low- to mid-80s.

Generally quiet and warm weather will persist on Thursday as an
expansive upper ridge settles over the Southeast and Mid-Atlantic,
and ill-defined high pressure continues at the surface.  Thursday`s
highs will once again land in the mid-80s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 203 PM EDT Monday: Thursday night, the Southeast CONUS ridge
will begin to deteriorate in response to several northern-stream
systems butting up against it on the periphery of a deep upper low
over Ontario and Manitoba.  Although these systems will be steered
north of the forecast area, they`ll help the blocking ridge break
down, and by Friday, ripples of embedded upper energy will work
their way into the Carolinas.  Rainfall is likely along an advancing
cold front Friday evening and Saturday.  Both Friday evening and
again Saturday afternoon, models depict significant sbCAPE
developing (and LREF ensemble members only disagree on how much
instability we can expect , not whether it`ll develop at all).  So,
embedded thunderstorms are likely, but in a weakly-sheared
environment that should keep severe risk at bay.

Sunday and beyond, long-range guidance has begun to converge on the
development of a Bermuda high for the start of the next workweek,
which will set us up for a pattern more characteristic of July than
of early May.  Expect diurnal showers and thunder, and temperatures
back in the mid-80s by the end of D7.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR and dry across the terminals through
daybreak Tuesday as the western edge of a surface high continues to
extend into the western Carolinas. A cold front will approach out of
the west overnight into Tuesday morning before pushing across the
western Carolinas Tuesday afternoon into Tuesday evening. Rain
chances look to increase across the western terminals (KAVL and the
SC Upstate terminals) Tuesday morning so have VCSH during the
morning hours. KHKY and KCLT should remain dry through the morning
hours. Scattered -TSRA will be possible Tuesday afternoon, thanks to
daytime heating, across the terminals. Thus, have PROB30s for all
terminals starting Tuesday afternoon and going through early Tuesday
evening. Wind direction will remain S/SW across the terminals
through the period. Low-end gusts are possible Tuesday afternoon,
especially at KCLT and KHKY. KAVL is the one exception as winds are
likely to toggle more W ahead of the cold front late Tuesday
afternoon. Cigs should generally remain VFR outside of -TSRA.

Outlook: Scattered showers and storms will remain possible into late
Tuesday evening, especially at KCLT. Isolated diurnal convection is
expected Wednesday through Friday. Higher coverage of diurnal
convection is expected on Saturday ahead of a cold front.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...AR/JDL
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...AR