693
FXUS62 KGSP 182351
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
751 PM EDT Thu Jul 18 2024

.SYNOPSIS...
A nearly stationary front will meander across our region through
early next week providing a focus for above normal chances of mainly
afternoon and evening showers and thunderstorms. Another cold front
will approach from the north later next week. Temperatures will be
near normal or just a bit cooler than normal.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 736 PM Thursday: The better convection has moved well east
of the fcst area, so as you are already aware, we cancelled our
end of the Svr Tstm Watch shortly before 23Z. Still expect to get
one or two more storms to develop in the area to the west of the
trailing stratiform rain region that was moving slowly east over the
Piedmont of the Carolinas. Evidence...the new cell that developed
in Pickens County SC, making the most of the remnant 1000-1500 J/kg
of sfc-based CAPE. The environment continues to stabilize, however,
so the storms will have a difficult time becoming severe. Precip
probs have been adjusted accordingly, as have the temps, thanks
to the cooling from all the earlier thunderstorm activity. Already
seeing some low dewpt depressions out there, so fog is looking like
a better and better possibility later this evening and overnight.

Otherwise, broad upper troffing will linger to our north over the
Great Lakes while broad upper ridging persists to our west and to
our east. At the sfc, Canadian high pressure will linger to our
NW while the Bermuda High keeps moist, southerly low-lvl flow
to our south. Between these two highs, a weak frontal boundary
that is currently draped across our area will slowly move south
and east of our CWA this evening. Nonetheless, the deeper moisture
associated with the broad region of low-lvl convergence will persist
over the Southeast well beyond the near-term period. The drier air
to our north, associated with the Canadian high, will make little
progress southward over the next few days. For Friday, we can expect
another round of sct to widespread convection across our area as
we remain under the moist airmass. The model profiles, however,
appear less supportive of strong to severe thunderstorms. Thus,
our primary threat will likely be localized heavy rainfall and
the potential for isolated flooding. As for temperatures, they
will trend cooler with highs on Friday expected to remain in the
80s over the lower terrain and 70s over the mtns.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 100 PM Thursday...A rather stationary pattern will persist
over the short range as a strong Canadian high builds south and
traps a frontal zone against the Bermuda High. The flow around the
subTrop ridge will will allow for very good moist advect each day
and cross sections indicate high saturation thru the mid levels. Fri
night into Sat may see the best chance for widespread showers and an
increased hydro threat as s/w forcing crosses the area. High cloud
cover and rather warm mid-levels will limit sbCAPE potential each
day as sfc heating and max temps are curtailed a cat or so below
normal, yet diff heating will likely allow for more robust and
longer lived tstms, possibly leading to a multi-cell mode. The
various guidance continues to disagree sigfnt/ly on the location of
the sfc convg zone which will be key in the generation and amts of
precip each day. Models aren`t too excited about over all precip
totals either, but localized areas could see arnd an inch in a short
amt of time potentially leading to flood issues depending on where
the sfc front interacts more with the stronger updrafts. Training
cells with high rainfall rates will also be possible as the mean
steering flow aloft aligns parallel with the stationary front thru
the period. Pops were maintained quite a bit abv climo each day with
lower noctural precip likely continuing each night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 140 PM Thursday...The ext range fcst remains quite active as
the latest guidance continues to show an activated stationary front
draped across the area each day. A strong subTrop ridge will hold
it/s own against upper energy diving out of Canada and possibly
strengthen and shift west by Tue. Decent agreement is seen in the
llvl mass fields Mon thru Wed with the GOM wide open for efficient
moisture flux each day. This could be a period of increased hydro
issues as antecedent water level conds by that time may be quite
elevated. A lot will depend on the areas where the front situates as
it wafts north and south thru the period, but the latest trends
begin to shift the heavy rain focus across the srn BR as the Bermuda
High becomes more dominant across the SE region. The going high-end
PoPs have been maintained thru the period including abv normal PoPs
during the overnight periods. Max temps will likely be held below
normal each day by a few degrees while mins remain abv normal.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: The immediate concern is a new patch of
storms just west of the KGSP/KGMU terminals, so brief MVFR can be
expected over the next hour or two. Otherwise, we have stabilized
in the wake of earlier storms. Moisture will remain pooled across
the region with a sfc front strung out along the I-85 corridor into
the overnight hours. Dewpoint depressions are already fairly low
for this time of day, giving confidence to the model depiction of
fog developing late this evening at all terminals, at least to an
MVFR vis restriction. Wind will be light/variable overnight. Some
locations should see at least temporary IFR in the pre-dawn hours,
with KAVL most likely to end up LIFR or VLIFR. There should be
some quick improvement by 13Z. For Friday, a bit of a later start
to the shower/tstm activity possibly because of extensive morning
cloud cover. The guidance eventually develops the convection in
the late afternoon and moves it northeast across the region. Will
keep that mention to a PROB30 at all terminals, but a TEMPO at
KCLT in the evening hours based on the HRRR timing.

Outlook: Expect sct to numerous showers and thunderstorms each
aftn/ evening thru the weekend. Morning fog/low stratus will be
possible each day, especially in the mtn valleys and over areas
that received rainfall from the previous day.

&&

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

&&

$$

SYNOPSIS...DEO
NEAR TERM...JPT/PM
SHORT TERM...SBK
LONG TERM...SBK
AVIATION...PM