Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
235 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 WEDNESDAY/...
As of 2:15pm EDT Tuesday:  Thunderstorms, with a few possibly
reaching severe levels, are anticipated this afternoon and tomorrow
afternoon. A large upper low remains in place centered over Central
Canada, with a circulation that extends marginally down into the
Southern States. Dynamics over the GSP area are quite weak, with
scarcely any deep layer shear. Upper and lower high pressure lies
off the Atlantic Coast, giving light to variable mostly southerly to
southwesterly flow to the region. Synoptic features have small
changes over the next 24 hours, with upper North American low making
some slight eastward progress. Southerly flow will keep dewpoints
and temperatures several degrees above normal. Afternoon MLCAPE
levels will be around 1000 j/kg today and tomorrow, with very little
shear or forcing to help things along.  Still, instability levels
are sufficient for a severe storm or 2 in afternoon heating. High-
res models indicate some uptick in strength of storms Wednesday
afternoon relative to today, possibly due to marginally improved
upper dynamics.  Slow movement of storms today and tomorrow suggest
some chance for isolated flooding if storms linger too long in one
location.

Convection today and tomorrow should fade after sunset.  With high
dewpoints and some areas with recent rain, fog has been forming in
mountain valleys overnight, which is expected again tonight.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
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 NIGHT THROUGH MONDAY/...
As of 145 PM EDT Tuesday: PoPs continue to increase into Saturday as
a front pushes into the southeast CONUS.  By now, moister profiles
and falling heights should allow for widespread rainfall ahead
of the front; although cloud cover should be building Saturday,
somewhat hindering destabilization, it's likely we'll see some
embedded thunder in the afternoon.  Once again, localized heavy
rain will present a flooding concern.  As the frontal zone reaches
us on Sunday, we'll ramp up to ever-higher PoPs in the morning.

Early next week, all the global models agree we'll come under
the influence of PTC 6.  Although there remain significant track
differences between models and to some extent from run to run,
the general consensus is that the system will track up the west
Florida coast before turning more northward.  What local impacts
we'll face is unclear, though heavy rain and ensuing flooding
is certainly a possibility, especially as the extensive rainfall
we'll have received prior to PTC 6's arrival should have raised
soil moisture and primed the ground for flash floods.

&&

.AVIATION /19Z 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...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High  94%     High  95%
KHKY       High 100%     High 100%     High  95%     High  95%
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...DEO
NEAR TERM...WJM
SHORT TERM...MPR
LONG TERM...MPR
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
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

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

SCZ012-019-101900-
Laurens SC-Greenwood SC-
229 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of south central
Laurens and east central Greenwood Counties through 300 PM EDT...

At 228 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles east of Greenwood, or near Greenwood State Park, moving east at
10 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...
Lake Greenwood State Park, Lake Greenwood, Greenwood State Park and
Dyson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

If on or near Lake Greenwood, get out of the water and move indoors
or inside a vehicle. Remember, lightning can strike out to 10 miles
from the parent thunderstorm. If you can hear thunder, you are close
enough to be struck by lightning. Move to safe shelter now! Do not
be caught on the water in a thunderstorm.

&&

LAT...LON 3414 8198 3425 8204 3431 8194 3431 8188
      3430 8190 3424 8191 3420 8194 3420 8193
      3418 8192 3418 8191 3416 8191 3414 8189
      3413 8187
TIME...MOT...LOC 1828Z 258DEG 10KT 3422 8196

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

CAC

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

NCZ053-101915-
Buncombe NC-
246 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of central Buncombe
County through 315 PM EDT...

At 246 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles west of Downtown Asheville, or near Leicester, moving east at
10 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, Woodfin, Weaverville, Biltmore Forest, Leicester, B.R.
Parkway-Nc Arboretum To East Asheville and UNC-Asheville.

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 3554 8272 3567 8274 3574 8253 3551 8248
TIME...MOT...LOC 1846Z 262DEG 7KT 3562 8265

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

CAC

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

NCZ064-065-101915-
Transylvania NC-Henderson NC-
249 PM EDT Tue Aug 10 2021

...A strong thunderstorm will impact portions of east central
Transylvania and south central Henderson Counties through 315 PM
EDT...

At 248 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles east of Brevard, or over Dupont State Forest. This storm was
nearly stationary.

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...
Brevard, Etowah, Dupont State Forest, Laurel Park, Little River In
Transylvania County, Penrose, Crab Creek, Cedar Mountain and Horse
Shoe.

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.

&&

LAT...LON 3514 8269 3526 8273 3534 8254 3519 8247
TIME...MOT...LOC 1848Z 251DEG 4KT 3521 8261

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

MOORE