809
FXUS62 KGSP 120729
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
329 AM EDT Thu Jun 12 2025

.SYNOPSIS...
Seasonably warm and humid weather, with numerous showers and storms
each afternoon and evening, can be expected through the weekend. A
warming trend will occur early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 148 AM Thursday: A more typical warm and humid summer pattern
featuring above normal chances for diurnal convection returns across
much of the area today. Progressive northern stream flow will remain
draped across Canadian border with a building Bermuda high over the
southeast states. Farther upstream, over the Southern Plains, a weak
closed upper low will slowly crawl eastward within a weak flow
regime. This will place the Southern Appalachians within moist
south/southwest flow. Early morning surface observations and low-
level ThetaE analysis depicts the previously stalled frontal boundary
lifting back north across the area as a warm front. As of this
writing, the boundary is draped along the I-85 corridor with
guidance in good agreement that it will continue to lift north
through the day. Deep moisture will nudge into the area behind the
warm front with dewpoints in the low 70s and PWATs climbing back
into the 1.5-1.9" range. Weak pieces of energy embedded within the
background flow regime will lift across the area today and help to
instigate scattered to numerous diurnally driven showers and
thunderstorms. Typical summer pulse convection hazards can be
expected with locally heavy rainfall and frequent lightning. A
couple strong storms with isolated gusty winds from wet microbursts
will be possible as well. Forecast soundings are rather unimpressive
for greater microburst potential, however, with tall/skinny CAPE
profiles, poor lapse rates and marginal DCAPE. Running environmental
values from modified near-storm forecast soundings through a local
microburst checklist confirms the poor setup with a microburst
composite value of 1, which is about as low as it gets outside of a
flat out 0. At least scattered showers and storms will likely linger
into the evening with activity finally dissipating by late
evening/midnight.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 130 AM Thu, key messages:

1. Southerly flow continues across the Southeast Friday and Saturday,
leading to deep saturation, abundant cloud cover, and daily chances
for showers and storms higher than climo.

2. Temperatures may actually dip slightly Friday compared to
Thursday, but will trend warmer again Saturday. Dewpoints will be
uncomfortably high, near 70 each afternoon in most areas.

3. Seasonable chances of localized heavy rain and isolated flash
flooding. A wet microburst producing strong to severe wind gusts
cannot be ruled out, although that threat will be mitigated by the
deep moisture.

South to southwest flow will continue Fri and Sat through the
atmospheric column, between Bermuda ridge and a shortwave in the
lower to mid Mississippi Valley. By most measures the last vestiges
of dry continental air (from earlier in the week) will be gone by the
start of the period Friday morning. PWATs will be above normal
through the day, likely in the 1.8 to 2 inch range per ensembles, and
change little Saturday.  Not much in the way of forcing other than
diurnal instability, but likely to categorical PoPs still result.
The shortwave axis inches closer by Saturday so PoPs trend a little
higher; QPF output doesn`t look any more organized but it would stand
to reason some slightly better lift could promote initiation.

Prog soundings each day unsurprisingly show deep saturation with weak
cloud layer flow and 0-6km shear. DCAPE and sfc-midlevel
delta-theta-e appear a little low to expect a particularly notable
risk of wet microbursts, although ensemble means depict CAPE in the
vicinity of 2000 J/kg each afternoon, so water loading may still
produce good downdrafts. Slow-moving storms producing torrential
rainfall arguably will be of greater concern.

Several models depict partial thicknesses declining from Thursday to
Friday, and accordingly slightly cooler temps in parts of the area
for Friday, a category or so below climo. Slightly higher thicknesses
and temps return Saturday, back to within a degree or two either side
of climo.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 215 AM Thu, key messages:

1. Shortwave trough to our west Sunday may promote increased precip
coverage in the NC mountains and northern foothills, but otherwise,
similar weather that day compared to Saturday.

2. The shortwave looks to pass Monday, turning low-level flow more
westerly and leading to a slight decrease in moisture aloft leading
daily PoPs to fall closer to climo Mon-Wed.

3. Temps trend warmer, slightly above climo Tue-Wed.

The major deterministic models all depict the axis of the shortwave
to the immediate west of the southern Appalachians Sunday. The zone
of deepest moisture looks to shift north of the area in some
guidance, and spread in PWAT increases among the LREF ensemble
members suggesting the possibility of some drying developing aloft.
QPF response becomes a little more concentrated across northern NC
and VA but also nearer the shortwave axis. PoPs trend up in our
western and northern zones. If drier air does work in, severe threat
may tick upward a tad, but heavy rain still appears the more likely
threat, particularly as saturated soils become more common in the CWA
following previous day`s storms.

The shortwave dampens Monday as it is absorbed into the midlatitude
flow across the US northern tier. Its axis looks to pass the CWA and
winds turn more westerly aloft. This is likely to reduce PWATs and
begin a slow decline of PoPs each day thru Wed, although coverage
still looks likely to be above climo. Downsloping appears to be
responsible for the rise of model blend temps that day, with airmass
modification and more sunshine supporting a continuing warming trend
thru midweek, with most Piedmont locations likely hitting 90 by
Wednesday afternoon. The potential for wet microbursts producing
damaging winds may increase as DCAPE is shown to trend upward in this
timeframe. Locally heavy rainfall remains possible... more or less
typical mid-June weather all around.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
At KCLT and elsewhere: Predominately VFR will prevail overnight at
all terminals. The most likely locations for any restrictions will
be at KAVL with possible valley fog and associated visibility
restrictions and KAND where an IFR to LIFR low stratus deck may
build in closer to sunrise. Otherwise, winds will remain light and
variable overnight. A busy convective day is expected this afternoon
into the evening with scattered to numerous showers and
thunderstorms across the area. Temporary reductions in visibility
from heavy rainfall rates will be possible at any given terminal.
Another round of patchy fog and low stratus will be possible again
overnight into early Friday morning.

Outlook: Mainly diurnal showers and thunderstorms are expected each
afternoon/evening through 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...Wimberley
NEAR TERM...TW
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...TW