Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
137 PM EDT Tue Aug 10 2021

.SYNOPSIS...
High pressure will persist off the Southeast coast, resulting in
a typical summertime pattern across the region this week. Abundant
moisture ahead of an approaching cold front will enhance coverage
of showers and thunderstorms, mainly in the afternoons and evenings.
The front is forecast to stall over the area this weekend,
maintaining good chances for rainfall.  A tropical system could add
to our rainfall in the first half of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of Noon EDT Tuesday: A few showers are beginning to form along
the Southern Appalachians, pretty much on schedule, with at least
scattered showers and thunder anticipated across the area as the
afternoon progresses.

Guidance is in good agreement that we should be a little more
unstable today, and PWATs will be running high (1.5-2.0"). So solid
chc PoPs across the Piedmont and likely in the mountains looks good.
Like yesterday, some storms may be slow-moving or get anchored on
the high terrain. So isolated flooding is possible today. The severe
threat still looks muted as moist profiles will limit DCAPE and sfc-
delta-theta-E values near the freezing level. But a couple of really
tall storms producing damaging wind gusts cannot be ruled out.

Tonight, convection should wane fairly quickly after sunset, but
guidance is hinting that debris cloudiness could linger well into
the night. But it should eventually dissipate during the pre-dawn
hours, leaving mostly clear skies. Perhaps a little more fog
potential in the mountain valleys and foothills than last couple
nights, owing to expected greater coverage of rainfall today. Lows
will be a category or two above normal.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 100 PM EDT Tuesday: A deep trough over the upper Midwest will
persist through the short term, while the Bermuda high will nudge
slightly westward in response to a building subtropical ridge over
the eastern CONUS.  On Thursday, as the ever-weakening boundary
draped across the Southeast pushes northward, southerly surface
flow will strengthen, advecting a plume of moisture into the region.
PWATs should climb well into the 1.7"+ range by Thursday afternoon.
With SBCAPE in excess of 1000 J/kg across the Piedmont and Upstate,
we'll be in store for another round of diurnally-driven pulse
convection.  In the absence of any discernible lifting mechanism,
and with midlevel drying promoting higher LFCs, widespread
convection should be somewhat suppressed.  Still, we're likely to
see isolated to scattered showers and thunder across the forecast
area, and with increasingly dry midlevels, a few of these storms
could produce downbursts.  The latest guidnace doesn't suggest
surface-to-700mb delta-theta-e values will be quite high enough
for a serious microburst threat, but the potential for some gusty
straight-line winds is there.

Friday will be a similar, if somewhat enhanced, scenario.  Guidance
depicts a 500mb shortwave rotating across the deeper trough over
the course of the day, resulting in increased DPVA and driving
increased PoPs beginning Friday afternoon.  Coverage of convection
should be enhanced on Friday afternoon as well - model consensus
points to SBCAPE in the 800-1200 J/kg range, and profiles should
be moister in the midlevels than on Thursday, making them more
conducive to convective initiation.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 215 AM Tuesday: It appears we will remain under an enhanced
diurnal convective regime into the medium range. Elevated PWATs
persist across the CWA; the Bermuda High appears to deepen a little
bit off the Southeast coast, and they begin to trend downward
slightly. A shortwave rotating thru the longwave trough over Canada
will help drive a cold front south into the Midwest and Ohio Valley;
ahead of that feature the global models respond with a gradual
increasing trend in QPF/coverage through Saturday. It doesn't look
like any appreciably drier air will make it this far southeast; max
temps will trend slightly higher Friday before falling back a tad
Saturday. The moisture plume along the frontal zone does reach us by
Sunday, and that day looks cooler via cloud cover and better PoPs.
Locally heavy rainfall will continue as an item of concern each day,
especially given that soils may become increasingly saturated
following multiple days with rain.

PTC 6 makes an appearance Sunday near the Florida Peninsula on each
of the GFS/ECMWF/Canadian deterministic runs. GEFS/GEPS ensemble
members mostly show the storm passing Florida into the Gulf before
turning northward. The various tracks are close enough to the CWA to
bear watching, but any local impacts would probably not occur until
near the end of Day 7. Our stormy pattern leading up to the storm's
nearest pass certainly suggests hydrologic issues would be likely if
we received TC rainfall. One saving grace based on the current progs
is that the pattern does not look especially conducive to a
predecessor rainfall event (PRE), lacking a well defined midlevel
trough and basically no support from the upper jet.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Showers and thunderstorms are beginning to
develop all areas this afternoon, and will potentially impact any
airport in the region through 00Z.  Convective instability is a
little higher than previous days, with possibly strong to severe
outflow winds from these storms.  Winds outside of effects of storms
are light to variable, with a south to southwest bias due to surface
high east of the region.  Surface pattern changes little through
Wednesday.  Fog is again expected this morning in the same places
where it occurred this morning, principally mountain valleys.  As
KAVL fell to 1/4sm this morning, will be a little more aggressive on
forecast fog for that location.

Outlook: Diurnal shower/thunderstorm activity remains in the
forecast the rest of the week.  Fog and low stratus will be possible
each morning, particularly over mountain valleys and areas primed
by rainfall from the previous evening.

Confidence Table...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     Low   53%
KHKY       High 100%     High 100%     High 100%     Med   73%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

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

&&

SYNOPSIS...Wimberley
NEAR TERM...ARK/WJM
SHORT TERM...Wimberley
LONG TERM...Wimberley
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
522 AM EDT Tue Aug 10 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-110400-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-
Rowan-Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
Caldwell Mountains-Greater Caldwell-Burke Mountains-Greater Burke-
McDowell Mountains-Eastern McDowell-Rutherford Mountains-
Greater Rutherford-Polk Mountains-Eastern Polk-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
522 AM EDT Tue Aug 10 2021

This Hazardous Weather Outlook is for northeast Georgia, piedmont
North Carolina, western North Carolina and upstate South Carolina.

.DAY ONE...Today and tonight.

Scattered thunderstorms will develop across the area today, with the
greatest coverage during the afternoon. Any of these storms will be
capable of dangerous cloud-to-ground lightning as well as heavy
downpours. Localized flash flooding may result.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Wimberley

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
119 PM EDT Tue Aug 10 2021

NCZ033-501-502-101745-
Caldwell Mountains NC-Greater Caldwell NC-Avery NC-
119 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of northern Caldwell
and southeastern Avery Counties through 145 PM EDT...

At 119 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles south of Blowing Rock, or near Blowing Rock In Caldwell County,
moving east at 20 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Blowing Rock In Caldwell County, Grandfather Mountain State Park,
B.R. Parkway-Linville Falls To Grandfather, Edgemont, Globe,
Patterson and Upton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3612 8155 3610 8152 3609 8145 3607 8144
      3607 8141 3605 8139 3604 8140 3604 8137
      3601 8134 3594 8178 3597 8182 3597 8184
      3609 8185 3611 8179 3612 8169
TIME...MOT...LOC 1719Z 252DEG 19KT 3607 8168

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

WJM

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
146 PM EDT Tue Aug 10 2021

NCZ033-050-501>505-101830-
McDowell Mountains NC-Caldwell Mountains NC-Burke Mountains NC-
Greater Burke NC-Greater Caldwell NC-Avery NC-Mitchell NC-
146 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of northeastern
McDowell, southeastern Mitchell, Caldwell, southeastern Avery and
northwestern Burke Counties through 230 PM EDT...

At 146 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Spruce Pine, or 7 miles south of Linville Falls,
moving east at 15 mph.

HAZARD...Winds in excess of 40 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...
Lenoir, Blowing Rock In Caldwell County, Cedar Rock, Crossnore,
Grandfather Mountain State Park, Table Rock, Linville Falls, B.R.
Parkway-Linville Falls To Grandfather, Edgemont and Pineola.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3611 8181 3612 8169 3612 8155 3610 8152
      3610 8150 3609 8147 3609 8145 3607 8144
      3607 8141 3604 8140 3602 8135 3600 8133
      3598 8133 3574 8206 3587 8209 3613 8182
TIME...MOT...LOC 1746Z 248DEG 13KT 3586 8195

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

WJM

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
152 PM EDT Tue Aug 10 2021

SCZ012-019-101815-
Laurens SC-Greenwood SC-
152 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of south central
Laurens and southeastern Greenwood Counties through 215 PM EDT...

At 152 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles east of Greenwood, or over Greenwood State Park, moving east at
15 mph.

HAZARD...Winds in excess of 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...
Ninety Six, Lake Greenwood State Park, Lake Greenwood, Greenwood
State Park, Ninety Six Historic Site, Dyson and Epworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3404 8202 3426 8207 3432 8185 3430 8190
      3424 8191 3421 8194 3420 8194 3419 8192
      3418 8192 3418 8191 3416 8191 3413 8187
      3410 8190 3409 8192 3407 8193
TIME...MOT...LOC 1752Z 248DEG 13KT 3421 8196

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

WJM

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
213 PM EDT Tue Aug 10 2021

NCZ053-101845-
Buncombe NC-
213 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of southwestern
Buncombe County through 245 PM EDT...

At 212 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles west of Downtown Asheville, or near Enka, moving east at 5 mph.

HAZARD...Winds in excess of 40 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...
Asheville, Bent Creek, Enka, Woodfin, Leicester, B.R. Parkway-Nc
Arboretum To East Asheville and Candler.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3569 8260 3548 8255 3547 8276 3553 8277
      3557 8277 3558 8278 3560 8278
TIME...MOT...LOC 1812Z 256DEG 5KT 3555 8271

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

CAC