410
FXUS62 KGSP 040553
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
153 AM EDT Thu Jul 4 2024

.SYNOPSIS...
Hot and humid conditions return for the second half of the week and
will linger into the weekend. Afternoon shower and thunderstorm
chances return on Thursday, mainly for the mountains. A cold front
will increase diurnal shower and thunderstorm chances across the
entire forecast area Friday into the weekend.

&&

.NEAR TERM /THROUGH TODAY/...
As of 145 AM EDT Thursday: Another quiet night with only some high
clouds dropping down from the north over the top of a few patches
of lingering high-based stratocu. No changes suggested.

Upper ridge over the Appalachian region will become more positively
tilted as a shortwave moves south of James Bay; weak frontal zone
will lay out near the Ohio River by daybreak Thursday. Sfc high
will weaken further, while our low-level flow continues to veer to
southwest. This flow appears less likely to foster low early-morning
cloud cover than what we this morning, but should maintain an
upward trend in dewpoints through Thursday, while max temps rise
back to around 90 in the mountain valleys and lower to mid 90s for
the Piedmont. Winds through the column will remain pretty weak.
Subsidence inversion looks weaker on prog soundings but still
persists such that areas near and southeast of I-85 still get
below- climo PoPs for Thursday. The inversion will weaken enough
that updrafts over the mountains look viable. CAMs however show
only spotty QPF response in that area, perhaps reflective of winds
being too weak to enhance initiation via upslope. A few vort blobs
could eject from convection in KY/TN nearer the front and provide
some enhancement, though. We will advertise mainly 20-30% PoPs for
isolated or widely scattered coverage for most of our mountains,
and higher 30-50% values along the TN border. PWATs are mostly
below 1.5 inches; rainfall is not particularly likely to cause
flash flooding despite slow storm motion.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
As of 120 PM EDT Wednesday: Mid level ridging will remain in place
across the region through the short range period. The expected
southwesterly low level flow will bring higher dewpoints back into
the area. The main issue is how high the will dewpoints get. Mid 70s
dewpoints are not that far away this afternoon, so they could easily
advect into our forecast area. However, with the dry ground in our
area we have to anticipate those readings could mix a bit lower
during peak heating. Confidence is not particularly high, but the
possibility of heat indices around 105 degrees exists in the lower
Piedmont and around Charlotte on Friday and Saturday afternoons.
Later forecast updates will have to fine tune whether this will be
an issue.

Otherwise, we do expect showers and thunderstorms to develop in the
hot and moist air in the mountains with the highest pops being on
Friday. Some storm activity will spill out into the Piedmont, but
pops will be lower there. Saturday looks like another active
convective day as a weak cold front drops into the area from the
northwest.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 130 PM EDT Wednesday: Mid level ridging will be in place
across the region with a seasonably warm and moist air mass
persisting. We don`t expect excessive heat indices but do expect an
active mainly diurnal shower and thunderstorm setup for Sunday
through early next week.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: VFR should prevail at all terminals through
the period. Only high thin clouds through daybreak for the most
part, but a few high-based stratocu will also linger. Wind will
be light/variable or calm until after sunrise, at which time the
direction should be SW as we begin to feel the approach of the next
system. Convection should not be as suppressed as the last few days,
and a further increase in moisture should fuel some development
of showers and storms mainly over the mtns/foothills. We start out
with a PROB30 at KAVL/KHKY and will evaluate the overnight guidance
to see if we can warrant a TEMPO instead. At this point, the rest
of the terminals are most likely to remain dry, with only a few
high stratocu. Around sunset, the wind will go light SW or variable.

Outlook: Typical mid-summer humidity and diurnal convection will
continue into early next week, leading to scattered TSRA and
possible restrictions each afternoon/early evening. Fog and/or
low stratus may develop each morning, especially for areas that
received rain the previous day.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...AR/PM/Wimberley
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...PM