953
FXUS62 KGSP 150732
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
332 AM EDT Mon Jul 15 2024

.SYNOPSIS...
High pressure lingers above the region through Tuesday. A pattern
change starts on Wednesday with a cold front forecast to stall west
of the area, resulting in cooler and more unsettled weather for the
latter half of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 305 am Monday: The pattern will remain more or less stagnant
through the near term, with a low-amplitude trough north of our area
extending southwest into more of a weakness in the subtropical ridge
across the Deep South. Today is expected to be a couple of degrees
warmer than Sunday...with some locations across the Piedmont likely
reaching the century mark. In addition, the atmosphere is expected
to begin moistening a bit from the SW. As a result, some locations
across our southern tier of zones could briefly reach Heat Advisory
criteria of 105 this afternoon. After collaboration with neighboring
WFOs, a Heat Advisory will be issued only for Union-NC for the time
being, but the margin for era is getting small, and this may need to
be expanded later this morning.

Otherwise, the atmosphere is forecast to destabilize more robustly,
with the weak capping inversion that was seen over the past couple
of days largely absent from this afternoon`s forecast soundings. A
consensus of guidance sources, including convection-allowing models,
support a solid 20% or so increase in PoP over what was observed
Sunday, with 30-50% covering much of the area, except for 60% in the
climatologically favored initiation zones closer to the Blue Ridge
escarpment. The increased instability should support more in the way
of strong storms today, while a couple of pulse severe storms are
possible. With precipitable water values expected to creep up close
to 2", a localized heavy/possibly excessive rainfall threat could
materialize, especially with any cells anchoring on terrain
features. Convection will diminish in typical fashion this evening,
with another very warm and muggy night expected.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 150 AM Monday: Synoptically, the CONUS remains under high
pressure, including the southeast. Flow aloft is weak Tuesday, but
profiles start to really moisten up. Guidance from modeled soundings
show another day with a stout inverted-V and around 1000 J/kg of
muCAPE. There is less dry air aloft to mix down during the daytime,
which suggests hot temps and hotter heat index values likely.
Diurnally driven showers and thunderstorms are possible with higher
chances (50-80%) in the mountains and (30%-50%) elsewhere. Despite
the higher humidity, if showers can get going, this could reduce
heat index values and provide some relief. Will continue to monitor.
The heat is likely to continue Wednesday, but not be as hot as a
pattern shift emerges. Long range guidance from the GFS/EURO signal
a developing upper low and trough across Canada, north of the Great
Lakes. This amplification leads to a trough dipping toward the south
by the end of the this forecast period. Flow aloft shifts more SW as
a cold front makes its way toward the area, stalling over Tennessee.
Though QPF response isn`t high, highest PoPs over the mountains
again (60%-80%) and (40%-50%) elsewhere for showers and
thunderstorms. Overall, heat busting precip and height falls toward
the end of the short term, sets up a rainy pattern in the extended.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 200 AM Monday: By Thursday, a weakened second trough begins to
protrude southward and sets up a persistent SW flow and moisture
advection into the area. Looking at long term guidance, this should
be the overall pattern through the end of the forecast period. QPF
response this far out at least shows rainfall, but how much cannot
yet be determined with confidence as the forecast will change.
Widespread PoPs each day with highest probability ramping up each
afternoon, especially over the mountains. As for temperatures,
expect a break from the heat for a while. Thursday will be the
warmest of the stretch. After Thursday, temps should start to
decline through the end of the weekend and into the start of next
week. Though temps will be lower, humidity is not expected to
decline as the front holds the dry air west of the CWA. Persistent
moisture advection keeps the area muggy, but cool through the end of
the period.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR conditions are expected to persist
through much of this forecast period. Can`t rule out a brief period
of restrictions in BR this morning at KAVL, but it`s unlikely.
Otherwise, an uptick in coverage of diurnal convection is expected
today above the past couple of days, and Prob30s for TSRA appear
warranted at all sites. Convection will diminish during the evening,
with little expected by the end of the period. Winds will generally
be calm or light/variable this morning, but will become SW at 5-10
kts during the afternoon.

Outlook: Isolated/scattered diurnal showers and storms are expected
mainly over the mountains through the middle of the week. Showers
and thunderstorms are expected to increase in coverage during the
latter half of the week as a cold front pushes into and stalls near
the region. Morning fog/low stratus will be possible each morning,
especially across the mountain valleys and for areas that received
heavy rainfall the day prior.

&&

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

&&

$$

SYNOPSIS...CP
NEAR TERM...JDL
SHORT TERM...CP
LONG TERM...CP
AVIATION...JDL