559
FXUS62 KGSP 140721
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
321 AM EDT Sun Jul 14 2024

.SYNOPSIS...
Hot high pressure persists into early next week, with isolated
showers and thunderstorms each afternoon. The pattern changes mid-
week as a cold front stalls across the area and brings above normal
rain chances and cooler weather.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 am EDT Sunday: Little change in the upper air pattern is
expected through the near term, with a broad/low-amplitude trough
expected to remain centered across the northeast quadrant of the
country, and a thermal/lee surface trough expected to persist east
of the Appalachians. Forecast soundings look relatively similar to
yesterday, with plenty of dry mid-level air...precipitable water
values near-to-a-little below climo...and moderately unstable but
also weakly capped air parcels. However, spot checks of various
point soundings do suggest that there could be a couple of hours
this afternoon in which the atmosphere becomes uncapped here and
there. All this spells a slight uptick in diurnal convective
coverage this afternoon, and 20-30 PoPs are forecast for much of the
area. A lack of robust instability will continue to yield a
non-existent severe storm threat, although we should see a bit more
lightning than was seen on Saturday. Max temps will see another
boost of a couple of degrees over yesterday...but deep mixing...
with some of dry air aloft finding its way to the surface...should
again preclude reaching Heat Advisory criteria (105)...except
perhaps on a very localized basis. However, plenty of 100-103 is
expected over the Piedmont. Convective coverage will diminish quickly
this evening, giving way to another warm and muggy night.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 150 AM Sunday: Starting off the week in a similar fashion to
the weekend, but hotter. The overall picture continues with most of
the the CONUS remaining under high pressure, including the
southeast. Flow aloft is weak, persisting stagnant conditions across
the area. Monday looks to have an uptick in moisture as guidance
suggests PWATS approaching the 2 inch mark, signaling a typical
muggy, summer day. Modeled soundings have another day of a stout
inverted-V and this time less drier air aloft. There could be some
instability, providing some fuel for showers and thunderstorms.
These would, however, be isolated and nothing outside of what is
expected during this time of year. Essentially, rinse and repeat for
Tuesday, with highest PoPs over the mountains. The so called bigger
story will be the heat, which exceeds summertime climo both days.
Heat index concerns for both days, with Tuesday being the most
likely for any Heat Advisory concerns. Monday could have a few areas
in the eastern NC Piedmont approach 105 degree heat index values.
Tuesday, there is higher confidence in widespread heat index values
approaching and exceeding 105 east of the mountains.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 200 AM Sunday: By Wednesday, a pattern shift emerges and heat
relief comes barreling down from the north. 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 height falls
across the eastern portion of the CONUS, and drifting across the CWA
on Wednesday into Thursday. Flow aloft shifts more SW as a cold
front makes its way toward the area. Guidance does have the front
stalling and eventually running out of steam west of the mountains,
but this sets up the area for much needed precip chances through the
end of the forecast period. At the surface, amplifying high pressure
off the east coast should setup a persistent SW flow and moisture
advection into the area. QPF response this far out at least shows
rainfall, but how much is still TBD as the forecast will change. As
for temperatures, Wednesday could see another day of hot temps and
similar heat index values of the day prior. Temps should start to
decline Thursday through the end of the weekend. 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 through the
end of the period.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions are expected to persist at all
terminals through the period, with perhaps some VFR cu/stratocu
developing this afternoon and evening. Isolated to widely scattered
showers, along with a few TS are expected to develop during the
afternoon. Other than a Prob30 for SHRA at KAVL, coverage is
expected to be such that no convective mention is warranted at the
other terminals. Other than calm or light/variable winds this
morning, predominantly Light SW winds are expected through the
period.

Outlook: Isolated/widely scattered diurnal showers and storms are
expected mainly over the mountains through early in 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