458
FXUS62 KGSP 112331
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
731 PM EDT Sun Aug 11 2024

.SYNOPSIS...
A stalled frontal zone will lead to isolated to scattered
thunderstorms this afternoon into the late evening. High pressure
builds in throughout the workweek with thunderstorms possible each
day. High temperatures be on a cooling trend starting today and will
continue cooler than normal into the weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 607 PM EDT Sunday: No major changes to the forecast.
Convective coverage over the Upstate has turned out a little more
impressive than anticipated, but is generally staying within the
bounds of the forecast.  Cells appear to be tapping into slightly
better instability and DCAPE than was initially forecast, resulting
in taller cores and somewhat pulsier convection in general.

Otherwise...the bulk of the forecast area still looks too suppressed
for anything more than isolated showers (likely not even that),
with the exception of the Upstate.  The HRRR`s latest few runs
depict the present activity over the Upstate gradually meandering
east over the next several hours, possibly holding together long
enough to reach the I-77 corridor.  By this time, it`ll be running
on fumes as instability will start to drop off quickly after sunset.
So, the severe risk still looks low though never zero.  Similarly,
given moist antecedent conditions, any sites where training occurs
could face some localized nuisance flooding.

Tonight, it should remain cloudy enough and winds should stay
elevated enough to preclude more than some patchy mountain valley
fog.  Remaining storms may persist past sunset, but should die off
by midnight if not sooner.  Temperatures will fall into the low 70s
or even upper 60s across the I-40 corridor and the NC Foothills.
Tomorrow, convection once again looks to remain isolated, with
virtually all the hi-res guidance depicting initiation remaining
confined to zones south of I-85.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 1250 PM Sunday...A broad upper trof gives way to a large
scale subs regime during the short range. This will enable more of a
convectively suppressed atmos with warming mid levels and dry dense
column air.

The latest NAM/GFS soundings show a strong cap arnd h7 in place by
Tue evening persisting thru the period, while deep shear increases a
little abv h85. A reinforced Canadian sfc high will dominate at the
surface which will make deep convec hard to come by each afternoon
owning to lowering sfc tds and maxTs. Also, PWAT values go down yet
remain a little abv normal...so storms that do develop will be
capable of producing stg downpours. Otherwise, not expecting much in
the way of stg/svr tstm development each afternoon with the NC mtns
likely receiving the brunt of the activity. The 12Z GFS is a notable
outlier in keeping a sfc trof active east of the mtns each afternoon
and this soln has been given little weight in the fcst process. Will
side with the lower PoP guidance values based on the overall
pattern, which includes a mix of consMOS.

Max temps will reach right arnd normal levels Tue, then drop a
couple degrees below normal Wed in continued n/ly to ne/ly llvl
flow. Mins will hover a little abv normal each morning.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 135 PM Sunday...Broad sfc high pressure remains dominant and
becomes reinforced Thu as a 1021 mb center develops across the srn
Glakes and builds down the east coast. This high will be supported
by a stg subs pattern aloft which will inhibit convec chances Thu
outside of upslope -shra/tstms instigated by moist e/ly flow within
the BL. The upper ridge begins to shift east early Fri and energy
rounding the axis may bring a nocturnal MCS to the NC mtns by
daybreak. Too far out for much detail in this scenario, but it may
be one to keep an eye on.

A transition occurs thru the rest of the ext range with a stg ulvl
trof pushing south out of Canada across the Midwest. The op models
as usual this far out have various timing and strength solns with
the GFS the most aggressive with an approaching cold front. However,
all models have the cold front activated and there looks to be good
shear and decent instability as it crosses into the area late Fri
evening or perhaps Sat morning per the more conservative GEM. In any
case, Sat daytime looks to be a convectively active day as the front
slows due to upstream occlusion. Thus, will keep abv normal PoPs
mentioned during this timeframe. Max temps will remain a little
below normal as a weak cP airmass mix continues, while mins remain
right arnd seasonal levels.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Widely scattered convection is still in place
across the Upstate along a weak frontal boundary settling across the
southern tier of the terminal forecast area.  The NC terminals still
look to remain suppressed through the TAF period, while the Upstate
terminals all have VCSH/VCTS this evening.  VCSH was introduced at
KCLT after midnight, when some hi-res guidance depicts lingering
showers drifting across the I-77 corridor.  The latest statistical
guidance is a little more aggressive than earlier forecasts with
mountain valley fog overnight, so MVFR visibility restrictions
were introduced to the KAVL TAF for a few hours.  Another round
of isolated convection is possible tomorrow, but coverage looks
too low to make it into any of the current TAFs.

Outlook: Expect generally isolated to scattered diurnal convection
across the region each day through the middle of the week. Patchy
fog and low stratus will be possible each night in the mountain
valleys and in locations that receive rainfall.

&&

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

&&

$$

SYNOPSIS...SBK
NEAR TERM...MPR
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...MPR