Severe Thunderstorm Warning 243, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
217 PM EDT Mon Aug 7 2023

.SYNOPSIS...
A cold front crosses our area tonight into early Tuesday. Showers
and thunderstorms will move east and south of our area this evening
as the front will become stationary over central South Carolina.
High pressure builds into the western Carolinas, leading to drier
weather Tuesday into Wednesday. Showers and thunderstorms return on
Thursday.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 200 PM: A potent shortwave is now centered over the middle
Ohio Valley, with sfc low now in SW Ontario, trailing a cold front
SW'wd to the Ozarks. Robust moisture plume preceding the front
is associated with 5000+ J/kg SBCAPE in much of AL/GA and up to
4000 invof the Southern Appalachians, per mesoanalysis. Short-term
progs depict values continuing to increase thru peak heating in
our CWA. Tstms developed rapidly ahead of the front around midday
and are set to propagate into our mountain zones within the next
1-2 hrs.

Shear parameters are generally better toward the north, nearer
the base of the shortwave. While the best forcing will pass by
to our north, strong mid to upper level flow will be present thru
the evening across our CWA. Effective shear will range from 30 to
50 kt which will promote the upscale growth; the better helicity
parameters appear to remain north and west of the area. DCAPE
has risen above 1200 J/kg across most of our CWA which will aid
in cold pool development. There is definitely better low-level
hodograph curvature toward the north as one might expect given the
above. Shear vectors being westerly, some potential for spin-ups
along the line(s) exists throughout. Embedded tornadic circulations
would however appear most likely in the north, and tornado watches
have been issued for much of our NC mountains and I-40 corridor. The
upscale growth and large DCAPE make the staight-line winds the
greatest concern for the remainder of the area, and we anticipate
a subsequent Svr Tstm watch will cover that threat.

Additional details forthcoming.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 141 PM EDT Monday: Wednesday's forecast continues to
look quiet, with much of the forecast area ensconced in dry WNW
flow behind a sagging surface boundary to our south, and high
pressure to our north.  Soundings indicate deep mixing to almost
700mb Wednesday afternoon, beneath a stout capping inversion that
should hold anything other than scattered cumulus at bay through
the day.  The cooler Canadian air mass ought to moderate our
temperatures...and indeed temperatures for all but the southernmost
tier of counties in the Upstate will struggle to get out of the
mid-80s, a good 5 degrees below normal for most locations.

Wednesday evening or overnight, a compact shortwave will pivot out
of the Ozarks and into the Southeast CONUS...permitting a return to
deep southwesterly flow and increasing moisture.  A surface front
will develop beneath this feature...to track across the Carolinas
on Thursday.  Upon its arrival, it may encounter another juiced-up
environment, with ensembles in favor of excellent instability (1500-
2000 J/kg per the ECE, as much as 2500 J/kg per some of the more
aggressive GEFS members) and elevated deep shear a good possibility.
There remains the issue of timing/overlap: a few of the operational
models don't quite bring the peak in rainfall/forcing in at the
right time to make use of afternoon instability (peep the 06z GFS
for example)...and there's still a good bit of ensemble spread in
the location of the upper shortwave, whose track will determine
how much shear we get.  Nonetheless, the most favorable forecast
soundings would put us at a risk of severe weather, while even
the most unfavorable soundings would still give us scattered
thunderstorms. So, Thursday looks active at the very least.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 159 PM EDT Monday: A pattern shift may be on the way as we get
closer to next weekend. Troughing will persist over the northeast,
but heights will rise subtly beginning Friday as the trough retreats
northward, allowing a subtropical ridge to build over much of the
southern U.S.  The 12z suite of operational guidance hints at
another shortwave making tracks across the Carolinas on
Saturday...which may induce some rainfall...or might just vanish
from the forecast before Saturday (isn't weather forecasting great?)
and leave us with diurnal rain chances more typical of mid-summer in
the Carolinas. By the end of the period, though, it appears that any
additional shortwaves will be shunted north of the Carolinas by the
building subtropical ridge, permitting a return to hot, humid,
seasonable conditions as the Bermuda High nudges westward and
Atlantic moisture creeps into the Carolinas.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Main impact this aftn/evening will be from
TSRA forming ahead of a cold front, which prompted TEMPO at all
sites. Storms over E TN are beginning to grow upscale from discrete
cells into a line, and the expectation remains that eventually
bow echoes will threaten all terminals with strong to severe wind
gusts and brief IFR vsby in +RA. A hail or tornado threat does
exist although those are more localized threats. TEMPOs timed per
CAM consensus; the wind threat should subside at all terminals by
00z at the latest, but a few stray lightning strikes trailing the
main line certainly could occur for an hr or two after the wind
threat. Overnight, some upslope driven precip may linger near the TN
border, and some MVFR cigs are possible at KAVL. Drying associated
with cold pools or with synoptic scale front will limit but not
completely inhibit nocturnal fog formation, especially where heavy
rain occurs. For now, confidence is greatest for fog in the WNC
river valleys, hinted at KAVL/KHKY. Low impact weather Tuesday
with low VFR cumulus, and SHRA chances currently too low to mention.

Outlook: Waves moving east along the front will bring daily
chances of scattered diurnal convection Wed through the end of the
week. Daybreak restrictions will be possible each day, especially
across the mountain river valleys.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 7 PM EDT this evening for GAZ029.
NC...Heat Advisory until 7 PM EDT this evening for NCZ071-072-082.
SC...Heat Advisory until 7 PM EDT this evening for SCZ009-011-014-
     019.

&&

SYNOPSIS...DEO
NEAR TERM...Wimberley
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...Wimberley

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Preliminary Local Storm Report
National Weather Service Greenville-Spartanburg SC
905 AM EDT Mon Aug 7 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0304 PM     Tstm Wnd Dmg     Due West                34.34N 82.39W
08/06/2023                   Abbeville          SC   911 Call Center

            A few trees were blown down around Due West.
            Also a power line down in the county.

&&

DEO

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Special Weather Statement
National Weather Service Greenville-Spartanburg SC
225 PM EDT Mon Aug 7 2023

SCZ102-103-105-106-071900-
Central Greenville SC-Pickens Mountains SC-Greater Pickens SC-
Greenville Mountains SC-
225 PM EDT Mon Aug 7 2023

...A strong thunderstorm will impact portions of northwestern
Greenville and Pickens Counties through 300 PM EDT...

At 224 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Pickens, or near Keowee Toxaway State Park, moving east
at 25 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Pickens, Easley, Lake Keowee, Jocassee Gorges, Lake Jocassee, Keowee
Toxaway State Park, Table Rock State Park, Six Mile, Berea and
Pumpkintown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3488 8291 3491 8290 3492 8291 3494 8290
      3495 8290 3495 8291 3496 8292 3497 8292
      3498 8294 3499 8294 3511 8254 3484 8247
      3481 8290
TIME...MOT...LOC 1824Z 258DEG 24KT 3492 8286

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

CAC

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
232 PM EDT Mon Aug 7 2023

NCZ052-053-064-065-071915-
Buncombe NC-Transylvania NC-Haywood NC-Henderson NC-
232 PM EDT Mon Aug 7 2023

...A strong thunderstorm will impact portions of north central
Transylvania, northwestern Henderson, southeastern Haywood and
southwestern Buncombe Counties through 315 PM EDT...

At 232 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles southeast of Waynesville, or 4 miles northeast of B.R.
Parkway-Balsam Gap To Black Balsam Area, moving east at 45 mph.

HAZARD...Wind gusts up to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Downtown Asheville, Waynesville, East Asheville, Arden, West
Asheville, North Asheville, Woodfin, Fletcher, Canton and Biltmore
Forest.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Tornado Watch remains in effect until 700 PM EDT for western North
Carolina.

&&

LAT...LON 3569 8251 3544 8239 3530 8293 3531 8294
      3531 8295 3532 8296 3533 8296 3537 8299
      3538 8302 3546 8306
TIME...MOT...LOC 1832Z 247DEG 39KT 3541 8294

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
240 PM EDT Mon Aug 7 2023

NCZ052-059-062>064-071930-
Transylvania NC-Haywood NC-Southern Jackson NC-Northern Jackson NC-
Macon NC-
240 PM EDT Mon Aug 7 2023

...A strong thunderstorm will impact portions of central Macon, west
central Transylvania, central Jackson and south central Haywood
Counties through 330 PM EDT...

At 239 PM EDT, Doppler radar was tracking a strong thunderstorm near
Franklin, moving east at 35 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Franklin, Cullowhee, Lake Glenville, B.R. Parkway-Black Balsam To
Mount Pisgah, B.R. Parkway-Balsam Gap To Black Balsam Area, Black
Balsam Area, Graveyard Fields, Lake Toxaway, Ellijay and Savannah.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Tornado Watch remains in effect until 700 PM EDT for western North
Carolina.

&&

LAT...LON 3510 8343 3526 8346 3541 8299 3532 8285
      3515 8284
TIME...MOT...LOC 1839Z 262DEG 29KT 3518 8336

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

MOORE