364
FXUS62 KGSP 291817
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
217 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 150 pm Monday: 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 Tue. 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 Tue 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 SUNDAY/...
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 /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: VFR conditions are expected for much of the
period. SCT cumulus in the 045-060 range are expected to continue
this afternoon, primarily at the upstate SC terminals, although some
of this could waft over KCLT by mid-afternoon. Otherwise, a cold
front will approach the area from the west overnight, and is
expected to cross the Terminal Forecast Area on Tuesday. A brief
period of MVFR cigs are possible ahead of the front around sunrise
Tue, but the forecast generally features low VFR cigs for the time
being. Shower chances will increase late in the period, warranting
Prob30s at most sites Tue afternoon. Chances for TSRA will also
increase after 18Z Tue, and a Prob30 is included at KCLT during that
time. SW winds of around 10 kts are expected this afternoon, with
occasional gusts of 15-20 kts possible. Winds will diminish to
around 5 kts tonight, before increasing again late Tue morning.

Outlook: Scattered showers and storms will remain possible into Tue
evening. Isolated, mainly diurnal convection is expected Wed through
Fri. Higher coverage of diurnal convection is expected Saturday.

&&

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

&&

$$

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