557
FXUS62 KGSP 112344
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
744 PM EDT Wed Jun 11 2025

.SYNOPSIS...
Seasonably hot and humid weather returns Thursday with numerous
showers and storms each afternoon and evening through the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 600 PM EDT Wednesday: An pronounced outflow boundary drifting
northwestward from convection over the Midlands is just entering
the SE edge of the CWFA. Based on the vis imagery, cannot rule
out an isoalted shower or thunderstorm along the boundary in the
lower Piedmont early this evening. The HRRR still favors a few
cells firing south of Charlotte. But with limited sbCAPE to work
with, don`t expect too much activity this evening. So PoPs look
on track. Otherwise, no major changes with this update. Continued
influence of sfc high pressure should promote fairly efficient
radiational cooling tonight, depending on influences from cloud
cover, with seasonal lows falling into the low to upper 60s.

Otherwise, a broad upper trof over New England will continue to
lift NE into the Canadian Maritimes. What`s left of an attendant
cold front will linger just to our south and east with drier post-
frontal air filtering across much of the region. Heights will rise
in the wake of the departing upper trof with increasing subsidence.
This should keep us mostly dry thru tomorrow morning, with the po-
tential for an isolated shower or t-storm across the far southern
and eastern reaches of our area in the vicinity of the stalled
frontal bndy.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 230 PM EDT Wednesday:

The short-term period will feature fairly typical summertime
weather as the region is sandwiched between a closed-low trough
largely detached from the westerlies over the middle Mississippi
River Valley and a seasonal subtropical ridge over the Atlantic. On
Friday, the upper-level pattern supports shortwave ridging over
the area, suggesting that the trough to our west will be unable
to provide appreciable forcing to the area.  Nevertheless, with
little inhibition, favorable profiles imply enough instability
via typical diurnal heating to result in above-normal shower and
thunderstorm coverage areawide.  Modest southwesterly flow through
the column supports weak shear, continued weak moisture advection,
fairly moist profiles, and shallow lapse rates. These parameters
are not conducive to a notable severe thunderstorm threat, though
they could support very isolated damaging wet microbursts, typical
for this time of year.  PWs will be approaching 2.00" across the
Piedmont, especially across our eastern zones, with flow vectors
supporting slow-moving or even training cells.  Therefore, there
is also an isolated excessive rain/flash-flood threat, but absent
appreciable forcing or focused moisture flux, this threat isn`t
significant enough to present a noteworthy concern.

On Saturday, the aforementioned upper low opens up and deamplifies
over the Ohio Valley as it begins to be absorbed into the
westerlies.  The proximity of this trough will be close enough to
aid in convective forcing, especially across our western zones,
with categorical PoPs forecasted over the mountains Saturday
afternoon and likely PoPs east.  Its proximity will also increase
bulk shear, with guidance in decent agreement that values will
approach 25kts over the mountains, otherwise, the profile changes
little from Friday.  While shear values might support a bit more
convective organization and a slightly higher damaging wind gust
threat, it appears the more prevalent impact will be heavy rainfall
given continued elevated PWs and Corfidi vectors supporting slow
storm-motion and possible cell training.  This once again presents
an isolated flash-flood threat not unusual for this time of year.
Expect near-normal temperatures both Friday and Saturday, but
humidity will be quite uncomfortable with dewpoints in the lower
70s across the Piedmont and near 70 in the mountain valleys.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 230 PM EDT Wednesday:

The shortwave trough influencing our weather in the short term is
expected to cross the area later Sunday into Sunday night, with
decent agreement across the guidance.  As such, above-normal diurnal
PoPs continue to be expected on Sunday with the column perhaps a
bit more moist compared to Saturday.  Lapse rates will be poor with
SBCAPE values perhaps a bit lower on Sunday compared to Saturday.
Bulk shear values below 15 kts also appear to be likely.  Therefore,
Sunday is expected to remain quite unsettled but as in prior
days, we lack an appreciable severe weather trigger.  Once again,
elevated PWs and poor storm motion vectors suggest areas of heavy
rain and isolated flash-flooding cannot be ruled out.  Overall,
however, model guidance agrees that we lack the targeted support
necessary for a notable threat.  Temperatures and humidity values
remain similar to Saturday.

By Monday afternoon, the shortwave should be east of the area,
resulting in a more westerly mean flow.  However, yet another
shortwave trough is quickly approaching the area from the west so
we are certainly on a wash-rinse-repeat cycle with categorical
PoPs west and likely PoPs east.  No significant changes in the
severe or heavy-rain parameters and the subsequent threats are
currently forecast.  The westerly flow may support a slight uptick
in high temperatures to slightly above normal.  Unfortunately,
humidity values will remain uncomfortable if not oppressive.

Heading into the middle of the work week next week, there really
is very little change in the overall pattern.  The aforementioned
shortwave will slowly propagate east Tuesday into Wednesday,
but the guidance disagrees on exactly when the trough axis will
finally pass east of our area.  Nevertheless, Tuesday and Wednesday
will continue the persistent weather story of above-normal PoPs,
especially along and west of I-85, with no significant severe
thunderstorm or flash-flood threat.  There is general agreement
that behind this shortwave, ridging will exert a greater influence
on our pattern, especially by later next week.  As a result,
a slight increase in max temperatures is expected on Wednesday
that will likely persist beyond the current day 7.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Generally VFR tonight, however, guidance
is hinting at some low stratus and possibly some patchy fog
forming before daybreak Thursday, as moisture increases from the
south. Confidence remains low, so will go with few-sct low clouds in
the Upstate and at KCLT, and some MVFR vsby at KAVL. Whatever clouds
may form should scatter out quickly as they will be shallow. By
early aftn, a return of fairly decent coverage of diurnal showers
and thunderstorms across the region. Have PROB30 for TSRA at all
sites, starting at 18z in the Upstate and KAVL, then as coverage
expands north and east, start at 21z at KCLT and KHKY. Winds will
be light, generally favoring a S/SW direction.

Outlook: Mainly diurnal showers and thunderstorms are expected
each aftn/evening thru the weekend and early next week. There will
be potential for late night and early morning fog and low stratus
restrictions each day.

&&

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

&&

$$

SYNOPSIS...JMP
NEAR TERM...ARK/JPT
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...ARK