169
FXUS62 KGSP 111802
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
202 PM EDT Mon Aug 11 2025

.SYNOPSIS...
Abundant moisture over the Southeast will continue scattered to
numerous showers with mainly afternoon thunderstorms through
midweek.  As a somewhat shallow upper ridge builds over our region
during the last half of the week, temperatures warm to near normal
and continue through the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 140 pm: An upper trough will remain across the central
Conus through the near term, with the axis of a weak upper ridge
forecast to straddle the eastern border of our CWA. Resultant deep
southerly flow will continue to support high moisture content,
with PWAT`s near 2 inches expected through the period.

This air mass has destabilized to the tune of sbCAPE of 2000-2500
J/kg across the Piedmont...displaced from locations that remain
relatively cool due to morning widespread/upslope showers and
storms. Deep convection is steadily expanding within the more
unstable air, and 60-80 PoPs are warranted across most of the CWA
through the afternoon. While convective coverage is forecast to
diminish in intensity and coverage this evening, the pattern will
support at least scattered lingering coverage through the night. In
fact, there is an emerging consensus that coverage may increase to
numerous+ toward daybreak as a low level jet increases to around
20 kts. Fortunately, this flow is forecast to veer to more of
a S/SW regime, so we should not see a repeat of the widespread
upslope heavy rain that was observed across the NC foothills this
morning. Nevertheless, the threat of heavy rainfall will continue,
with locally excessive rainfall possible, especially if heavy rain
does manage to materialize again over the NC foothills, where 2.5-4+
inches have fallen since this morning.

Convective trends will be a little difficult to pin down for Tue
afternoon, as destabilization will depend upon if and where morning
convection becomes prevalent. Nevertheless, the pattern will be
supportive of at least scattered activity during the afternoon, and
60-80 PoPs are advertised across most of the CWA, with heavy/locally
excessive rainfall remaining the primary concern. Min temps tonight
will be a little above normal, maxes will be 5-10 degrees below
normal under persistent cloud cover.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 1213 PM Monday: Upper ridging over the Atlantic slowly
retrogrades and becomes centered over Florida and far southern
portions of the Gulf states by Wednesday into Thursday. While
heights will slowly rise across the region, the southern
Appalachians will remain on the northern flank of the ridge with a
wetter pattern continuing into at least Wednesday morning. The first
focus of the short term period will be overnight Tuesday night into
early Wednesday morning as a well defined trough slides across the
Great Lakes region. Low-level mass response to a deepening low over
southern Ontario in concert with anticyclonic flow around the upper
ridge will draw a plume of deep moisture across the area from the
south/southwest. PWATs will surge into the 2-2.25" range, which is
well above the 90th percentile and would challenge the daily record
high PWAT at Peachtree City, GA. A 20-30kt low-level jet along with
a mid-level speed max will also translate across the area with
copious moisture transport in the cloud-bearing layer. Forecast
soundings reveal deep saturated profiles with moderately high
freezing levels and 500-1000 J/kg of MUCAPE. The result will be the
potential for a cluster of convection to lift out of north Georgia
and into the area generally along and north of I-85. This activity
may also be accompanied by a meso low which would further provide
support and focus to any convective cluster. Given the
aforementioned environment, these showers and storms would be
capable of producing very efficient rainfall with locally heavy
rainfall of 2-4" possible with isolated higher totals not out of the
question. As such, will need to closely monitor the potential for at
least a few instances of flash flooding overnight Tuesday night into
early Wednesday morning.

Plentiful coverage of convective debris clouds could throw a wrench
into the forecast for the remainder of the day on Wednesday. More
typical diurnally driven convection will be possible where breaks in
the clouds occur and more warming and subsequent destabilization
materialize. High temperature forecast may also be in jeopardy with
a cloudier forecast likely cutting a number of degrees off of the
currently forecast highs. A somewhat similar pattern continues into
Thursday as the center of the upper ridge becomes fully established
over Florida. Very deep moisture remains entrenched over the area
with the potential for another overnight bout of locally heavy
rainfall followed by the potential for diurnal afternoon/early
evening convection. Forcing mechanisms become more nebulous early
Thursday morning with mesoscale details that are too murky at this
time range playing a large role in driving any overnight convection.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 1257 PM Monday: Heading into Friday and the weekend, upper
ridging over Florida continues its slow retrograde with the center
of the ridge gradually shifting west along the Gulf Coast and
becoming focused over far southeast Texas into Louisiana by Sunday.
More seasonable late summer weather returns with highs around normal
and a chance for isolated to scattered diurnal convection each day.
Flow eventually shifts to out of the northwest late in the period as
the upper ridge inches westward with the potential for a couple weak
waves to drop across the Ohio Valley and towards the area. If this
were to occur it could support a focus for greater coverage of
storms, but forecast confidence remains low that far out.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Showers and thunderstorms are increasing
in coverage across the Piedmont this afternoon in a very moist
and increasingly unstable environment. TS will be most prevalent
across the Piedmont (i.e., KCLT and KAND), and tempos for TSRA
are carried there at some point this afternoon. TS are possible
elsewhere, but VCTS, along with tempos for SHRA are carried at
most sites for now. Any lingering IFR cigs are expected to improve
to MVFR no later than 20Z, while all sites should improve to VFR
late this afternoon/this evening. Although the intensity and
coverage of showers and storms should diminish through the evening,
the pattern will support scattered activity through the night, with
some high resolution guidance sources suggesting another round of
numerous coverage may develop toward daybreak Tue. For now, this is
handled with a protracted VCSH mention, while Prob30s for TSRA are
advertised in the 09-15Z time frame, mainly at the upstate SC
terminals. Cigs are otherwise forecast to lower again tonight, with
no better than low MVFR conditions expected after midnight. Reduced
visby in SHRA and/or BR is also expected during that time frame.
Winds will generally be between light ENE and ESE through much of
the period.

Outlook: Mostly diurnal showers and thunderstorms with associated
restrictions are expected across the area each day this week,
with a period of more widespread showers and storms possible
Tue night/early Wed. Morning fog/low stratus is also possible,
especially across the mountain valleys.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JDL
SHORT TERM...TW
LONG TERM...TW
AVIATION...JDL