539
FXUS62 KGSP 060002
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
802 PM EDT Fri Jul 5 2024

.SYNOPSIS...
Above normal temperatures will persist through the weekend.
Meanwhile, a cold front moves in from the north and becomes
stationary near the southern portion of the forecast area on
Saturday. This front will increase the chance for thunderstorm
activity outside the mountains through Sunday. More typical
summertime thunderstorm development returns Monday and persists
through next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 530 PM Friday: For the evening update, showers and
thunderstorms are ongoing throughout the CWA, especially in the NC
mountains and western SC Upstate. A few of the storms have become
severe and the threat for further severe thunderstorms is not over.
Made some adjustments to temps given the outflow from many of these
storms cooling areas off. Slight adjustments to PoPs given the high
amount of storm coverage.

Thunderstorms will remain numerous across the mountains through late
afternoon with scattered activity developing into the Piedmont
through mid-evening within the axis of 2500-3500 j/kg SBCAPE values.
Decent enough storm motion should limit the excessive rain threat,
but we will continue to monitor for any training storms, especially
in the high terrain.  Thanks to an axis of moderately high downdraft
CAPE values analyzed across the piedmont, there remains the
potential for a few storms to produce damaging wind gusts.
Otherwise, after storms ash out, temperatures will remain warm all
night with daybreak minimums flirting with record high minimums.
More summertime storms are expected on Saturday as baroclinic zone
activates, aided by vort energy translating into the region within
the moderate sw flow aloft.  The short range model consensus
actually has the better forcing east of the Blue Ridge tomorrow,
where cvrg should blossom to numerous. Just like today, there is the
ongoing threat for isolated excessive rainfall and damaging wind
gusts.  The llvl thickness ridge shifts east away from the region on
Saturday displacing heat advisory concerns to the I-95 corridor and
coastward.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 200 pm Friday: A broad long wave trough will be centered
across the central Conus through the short term, with the southern
Appalachians and vicinity expected to be near the southern periphery
of the subtropical jet. A surface boundary...perhaps being displaced
by a lee/thermal trough with time, will remain over or near our CWA
through the period, which in light of continued very moist
conditions (PWATs at least the 75th percentile in terms of
climatology through the period) will continue to enhance diurnal
convective chances early in the new week. Above-normal coverage of
convection is expected both Sunday and Monday afternoon/evening,
with general likely PoPs forecast over the mountains, and 50-60%
chances across the Piedmont both days. Instability will be adequate
for multiple strong+ storms, with a few pulse-y or multicell cluster
severe storms possible. Unusually high moisture, along with cell
motion of < 10 kts, and some potential for training storms will
yield a threat for locally excessive rainfall both days, especially
for locations that see multiple days of heavy rainfall. With the
increased activity and expected relatively early start to convective
initiation...as well as lower heights aloft, temps will be cooler
than they`ve recently been...generally around or even slightly below
climo.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 225 pm Friday: The early portion of the medium range will be a
battle for influence on the weather across the southern Appalachians
between an upper trough across the central Conus, and a subtropical
ridge over the western Atlantic. The consensus of the latest global
model guidance suggests the ridge may begin to win the day toward
mid-week. Thus, PoPs for diurnal convection will trend down closer
to climatology Tue/Wed. A few strong-to-severe storms producing
microbursts and locally heavy rainfall will remain possible,
although with a diminishing threat due to fewer targets of
opportunity. (There will almost certainly be pockets of the CWA with
relatively poor antecedent conditions, so the excessive rainfall
threat will remain elevated for those areas.) Moisture associated
with the remnants of T.C. Beryl pose a potential fly in the forecast
ointment late in the period. However, the GFS and Canadian tend to
spin the cyclone down over Texas, while even the ECMWF...which has
consistently maintained a closed circulation into the Tenn Valley in
the Day 5/6 time frame...keeps the notable impacts very close to
the center. So...even indirect/minimal impacts appear unlikely for
our area at this time. Temperatures are forecast to remain within a
degree or two of climo through the period.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Prevailing VFR conditions to start with at
most terminals. As the evening calms down from afternoon showers and
thunderstorms, sites should see improvements in vsby. Overnight, a
few areas of patchy fog could offer at the mountain terminals that
received rain earlier, such as KAVL and KHKY. A weak front stalls
over the area overnight as well, which brings winds from the W/NW
for a few hours by daybreak at KGSP/KGMU. KAND should reach westerly
winds but return southerly by the end of the TAF period. Expect
winds outside the mountains to return to a southerly direction by
Saturday evening. Another round of scattered TS possible Saturday
afternoon. Most sites have a PROB30 for TSRA, but confidence is not
high enough to put in a PROB30 at sites KAVL and KHKY at this time.

Outlook: Typical summertime convection will continue through the
weekend and into early next week, leading to sct 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...SBK
NEAR TERM...CP/CSH
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...CP