852
FXUS62 KGSP 062159
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
559 PM EDT Sat Jul 6 2024

.SYNOPSIS...
A weak front will move in from the north and become stationary near
the southern portion of the forecast area today. This front will
increase the chance for thunderstorm activity outside the mountains
through Sunday. An active pattern of afternoon and evening showers
and storms is expected to continue through next week.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 530 PM Saturday: For the evening update, the remaining
boundary remains south of I-85, keeping ongoing showers and
thunderstorms on the south/eastern fringe of the CWA. Taking a look
upstream in GA, IR satellite shows the strongest convection and
coldest tops along the boundary. Given the current lower moisture
profiles and instability in the Upstate, confidence is low for
storms making it north of I-85. However, if the boundary starts to
lift this evening, it`s possible to still get a stray storm.
Adjusted Pops a bit to reflect the higher amounts (60%-80%) along
and east of the boundary.



Broad longwave troughing is currently draped
across much of the CONUS from the Pacific Northwest to the Ohio
Valley. Stout upper ridging remains centered over California along
with a second ridge that has shifted off the east coast. A cumulus
field is attempting to recover over north Georgia in the wake of a
deck of high overcast stratus, but this attempt might be in vain
with limited time left for destabilization and convective
initiation. Thus, confidence in convection is highest south of I-85
through the afternoon although a couple isolated showers and storms
cannot be discounted across northeast Georgia and the northern
Upstate along with a stray shower or two across the mountains.
Modest instability will support the potential for a couple strong
storms, but severe weather potential is low owing to poor lapse
rates and limited DCAPE.

A few showers may linger into this evening and possibly the
overnight as southeasterly flow returns to the area and the stalled
boundary slowly lifts back north into the mountains. A widespread
deck of low stratus clouds is expected to develop, which will
further limit any cooling in the face of moisture return. This will
keep overnight lows on the mild side with upper 60s to low 70s. By
tomorrow, little change is expected with regards to the synoptic
pattern. Coverage of showers and storms is expected to be greater,
however, given the return of rich low-level moisture and ample
instability. Showers will likely develop earlier in the afternoon
with storms increasing in coverage as well, especially across the
escarpment and I-85 corridor. Morning cloud cover and an early start
to convection will not only keep temperatures in check, but will
also limit instability with surface-based CAPE progged at 2000-2500
J/kg. As with any summertime convection, isolated damaging wet
microburst cannot be ruled out, especially where multicell
clusters/cell mergers occur.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 145 pm Saturday: The western Carolinas and northeast GA will
be stuck in a weak upper flow regime between a long wave trough
centered over the central Conus, and the subtropical ridge extending
from the western Atlantic into the Southeast. A deep, albeit weak SW
flow will maintain very moist conditions across our area through the
period, with precipitable waters expected to be above the 90th
percentile of early summer climatology. With synoptic features
lacking, precip chances will be strongly tied to the diurnal heating
cycle, with the high moisture levels expected to result in
higher-than-normal coverage of diurnal convection. PoPs for
afternoon/evening showers and storms are generally 50-60% across the
Piedmont, and 60-70% across the mountains for Monday and Tuesday.
The main convective threats through the period will be locally
excessive rainfall, as slow-moving, efficient rainfall-producing
storms are expected. However, sufficient instability should be
available both days to support a handful of pulse severe storms. The
very moist conditions should support some degree of convective
coverage (albeit diminishing) well past the typical diurnal
convective cycle, likely accompanied by a small heavy/excessive
rainfall threat.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 210 pm Saturday: The upper air pattern is expected to remain
relatively static during the extended, with a central Conus trough
expected to make only modest eastward progress, while the
subtropical ridge/associated Bermuda high is forecast to strengthen
across the western Atlantic. With such minimal changes in the
overall patter expected, the environment over the southern
Appalachians and vicinity is expected to remain more moist than is
typical for early summer. This moisture could be enhanced further
(albeit briefly) by the remnant circulation of T.C. Beryl, which is
forecast to lift across the TN and OH Valleys during mid-week.
Above-normal coverage of diurnal convection (60-70 PoPs across the
mountains; 50-60 across the rest of the area) is therefore expected
each day through the period. An excessive rainfall threat will
continue...and may actually worsen a bit as antecedent conditions
deteriorate locally. Temperatures are forecast to be within a degree
or two of climo through the period.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions are currently ongoing at all
terminals with an afternoon cumulus field being observed, especially
outside of the mountains. Afternoon showers and thunderstorms are
expected generally along and south of I-85 with the highest
confidence at KAND and KCLT. KGSP/KGMU are on the drier side of a
weak cold front and may be just a hair too far north for convection
to impact the terminals, but it would be premature to can the TEMPOs
just yet. The TEMPO was dropped at KHKY, however, with the KAVL
TEMPO transitioned to SHRA as confidence in convection is lowest
along the I-40 corridor farther into the drier air behind the front.
Heading into tonight, the front shifts back north allowing deeper
moisture to return across the area and the development of a
subsequent low stratus deck east of the mountains. MVFR to IFR
ceilings are likely with a few instances of LIFR not out of the
question. Patchy fog cannot be ruled out as well, but may end up
being limited to locations that see rainfall today. Otherwise, winds
will be light and variable through much of the period with
north/northeast winds on the north side of the front and southerly
on the south side.

Outlook: An active summertime pattern will continue for most of next
week, leading to scattered to numerous showers and thunderstorms and
possible restrictions each afternoon/evening. Fog or low stratus may
develop each morning, especially over areas that received rain the
previous day.

&&

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

&&

$$

SYNOPSIS...JDL
NEAR TERM...CP/TW
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...TW