051
FXUS62 KGSP 151607
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1207 PM EDT Sun Jun 15 2025

.SYNOPSIS...
Hot and humid with daily showers and thunderstorms expected through
most of the week. A cold front arrives early Friday, with drier
conditions returning behind it heading into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1135 AM EDT Sunday: A few changes to the PoPs given current
trends which reduces the chances for showers over the next few
hours. Scattered clouds are currently over the CWA, but there is
some sunshine reaching the ground. A few light showers coming up on
the radar but not much else is occurring.

One more day of enhanced diurnal showers and storms as what`s left
of the old upper trof lifts out to the north today. Forcing looks
weak at best, but perhaps enough to give us an earlier start to
the deep convection across the mtns and northern tier late this
morning. The day looks similar to Saturday as we have the same air
mass with muCAPE around 2000 J/kg and maybe 20 kt of deep layer
shear, but otherwise poor lapse rates and low dCAPE. Won`t rule
out an isolated strong/severe multicell, but chances are better
to our east. The greater concern will once again be heavy rain and
isolated flash flooding, particularly across the nrn foothills and
northwest Piedmont where some heavy rain has fallen in the past
24 hours or so. The generally scattered nature of the convective
precip, modest probability matched mean 6 hr precip amounts,
and modest QPF all suggest that flash flood potential is not high
enough to warrant a Watch across our forecast area. That being said,
it is worthy of keeping track of any persistent precip. Temps will
be near normal with fairly high humidity again. With the remnant
trof axis to our east by late evening, we should see much more
of a diurnal tendency with the precip, so by midnight or so it
should dissipate. That will leave us with a night even more quiet
than what we`ve had lately. High pressure will attempt to filter
in from the northwest in the early morning hours. Some of the
guidance hits the dense fog potential fairly hard, so that will
also have to be watched. Lows will be mild once again.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 211 AM EDT Sunday...

Key Messages:

1) Afternoon showers and thunderstorms develop on Monday and
Tuesday.

2) Temperatures climb above normal to start out the workweek.

3) Hot, muggy conditions continue and worsen as the week wears on.

Unsettled weather will continue into the workweek as the Carolinas
remain ensconced in southerly moisture flux on the western periphery
of the Bermuda High.  Poor lapse rates and very weak flow aloft will
inhibit stronger updrafts and convective organization...instead
favoring slow-moving storms with efficient rain production amid
PWs of 1.5-1.75".  So, diurnal convection will pose more of a
hydro risk than a severe risk.  Temperatures Monday will upper
80s across the area, with isolated lower 90s possible south of I-85.

A weak z500 trough will push across the Ohio Valley on
Tuesday...deteriorating as it arrives on the East Coast, where
it`ll encounter the subtropical ridge and largely fall apart.
As a result, there`s precious little improvement of lapse rates,
and not much synoptic forcing over our area...so diurnal convection
on Tuesday will once again favor hydro risk over any severe threat.
Having said that, a weak midlevel speed max looks like it`ll creep
up the eastern limb of the trough, slightly enhancing deep-layer
shear...perhaps enough for some loosely-organized cells to develop
and therefore permitting a higher severe risk than on Monday.
A tad more dry air in the 700-500mb layer would also suggest low-end
potential for damaging winds.  Meanwhile...temperatures will get
increasingly sultry...with heat index values expected to climb into
the upper 90s Tuesday afternoon...possibly hitting 100 degrees in
isolated areas south of I-85.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 253 AM EDT Sunday...

Key Messages:

1) Diurnal convection continues each day through Wednesday.

2) A cold front arrives Thursday night, possibly drying things
out going into the weekend.

3) The heat continues, with a possible break in hot/humid conditions
Friday, before continuing to heat up over the weekend.

The synoptic pattern won`t change appreciably for the remainder of
the week.  On Wednesday, the subtropical ridge is likely to begin
expanding north and west, further raising low-level thicknesses
and resulting further temperature increases.  Another z500 trough
will eject out of the Rockies, diving across the Great Plains
and pushing into the Carolinas by Thursday.  This won`t do much
to offset continued hot and muggy conditions Thursday...but will
diminish thicknesses going into Friday...so expecting a temporary
reprieve from unseasonably hot conditions on Friday.  LREF ensembles
have begun to coalesce around a cold frontal passage between sunset
and midnight Thursday night...after peak heating, but early enough
that some instability might be present to tap into.  Still lots
of time for this to change...but would expect this to mean some
non-diurnal thunder is possible...and perhaps an associated severe
risk if other ingredients line up.

The heat will return over the weekend as thicknesses rise
again...but the humidity may not.  The 00z LREF cycle has trended
sharply toward drier postfrontal air working in behind the front,
with over 70% of ensemble members supporting a marked decrease in
dewpoints...especially for the NC zones.

&&

.AVIATION /16Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: The air mass across the region remains
warm and humid, thus a low cloud ceiling restriction could develop
just about anywhere at any time. The terminals closer to the Blue
Ridge Escarpment could be in-and-out of an IFR ceiling through
14Z, by which time the lowest clouds should be lifting to MVFR
and scattering. Either way, an MVFR ceiling will pop up quickly
with minimal heating by mid-morning and then persist to midday,
by which time the lowest clouds will scatter out and lift above
030. Scattered thunderstorms are expected in the afternoon and
lingering into the early evening. Confidence is best at KCLT in
the late afternoon. Looks more like a typical summer day, with
convective debris lingering into late evening, then quieting
down for the overnight. There has been some indication of a fog
restriction developing over the mtns in the pre-dawn hours Monday,
so KAVL looks like a good bet to fall to LIFR or worse.

Outlook: Showers and thunderstorms are expected each day thru early
next week. Late night and early morning fog and low stratus restric-
tions will be possible each day.

&&

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

&&

$$

SYNOPSIS...AR
NEAR TERM...CP/PM
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...PM