319
FXUS62 KGSP 070137
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
937 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 930 PM Saturday: At this update, convection has started to
taper off with a few lingering showers/thunderstorms south of I-85
and the NC Piedmont. Instability continues to decrease, reducing
storm potential. IR satellite shows shallow cloud tops over the CWA.
Made some adjustments to PoPs given the current downward trend and
temps with the cooler air from decaying storms.

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 few showers may linger into
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 /02Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR conditions to start out the TAF
period outside of areas with showers and TSRA this evening. Given
the widespread coverage of TSRA east of the mountains, TEMPOS for
all terminals expect mtn sites through at least 02z. VCSH are those
terminals are expected after the TEMPOs expire through at least
midnight. After midnight, winds will become VRB to calm at most
sites. Areas that received rain this evening will be prone to FG.
Confidence is medium that KCLT and KHKY will have CIGS drop into the
IFR range, with KCLT in this low CIG restriction from 07z-14z. MVFR
will return early morning and slowly improve to VFR by the afternoon
at all sites. Another round of TSRA expected Sunday afternoon at all
sites starting at 20z in the mountains and 22z elsewhere. As for the
winds, again VRB to calm overnight with wind speeds starting to pick
up again by mid morning, but still remaining light. Wind direction
should prevail S/SE after TSRA diminishes.


Outlook: A typical summertime pattern continues for most of next
week, leading to showers/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...CP