Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
634 PM EDT Thu Aug 12 2021

.SYNOPSIS...
A stormy pattern will persist over the area into this weekend, with
scattered if not numerous showers and thunderstorms developing each
afternoon. Temperatures will remain above normal through Saturday.
Cooler but still rainier weather will arrive Sunday with a stalling
cold front, a potential weak CAD, and possibly the remnants of
Tropical Storm Fred Monday night into Tuesday.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 630 PM EDT Thursday: Scattered showers and thunderstorms
continue to track across the mountains and I-40 corridor this
afternoon and should continue through sunset before fulling waning
off.

Otherwise, hot and muggy conditions settled into the area as
expected. This is due to the sub-tropical ridge which remains
dominant over the Southeast along with a persistent Bermuda High sfc
pattern. Scattered afternoon/evening showers and thunderstorms will
be in store across the fcst area, especially in the mountains where
differential heating on the slopes will be a reliable trigger. A few
storms will likely pulse up to severe levels again today thanks to
2000+ J/kg of SBCAPE and 500-1000 J/kg of DCAPE, with the main
threat being damaging wind gusts. The overall coverage outside of
the mountains is less than yesterday given the slightly higher 500
mb heights and model consensus of less CAPE than last couple days.
There will also continue to be a non-zero flash flood threat, given
the high PWATs still in place and slow storm motions expected.
High temperatures will continue to run a few degrees above normal.

Tonight, should see convection wane with loss of heating, leaving
debris cloudiness into the overnight, followed by patchy fog,
especially in the mtn valleys. Lows will be a couple degrees
above normal.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 130 PM EDT Thursday: Ridging over the SE CONUS will continue
to maintain a strong Bermuda high over the western Atlantic
Saturday, promoting southerly flow off the Atlantic coast and
helping PWATs jump as high as 2" across the Piedmont and Upstate.
A shortwave will swing across the region by Saturday afternoon,
promoting better synoptic forcing and steering a weak front through
the area late in the day.  This should enhance diurnal PoPs on
Saturday if the front moves through early enough - and model
consensus presently pushes the front out of the Appalachians
between 18Z and 00Z on Saturday afternoon, well-timed to take
advantage of peak afternoon heating.

With weak shear across the board, storms should struggle to develop
much organization, and even with the boundary we should be looking
at mainly pulse-type storms.  Not to say a few couldn't become
severe - if the last few days have taught us anything, it's that
the amount of instability and moisture this pattern is producing
can give us notable convection - so certainly can't rule out a
handful of severe cells.  However, the main threat at this time
will be localized flash flooding, as the environment is ripe for
moderately slow-moving, heavy rain-producing storms.

Sunday looks to be somewhat of a transitional period: behind
the front, high pressure should sweep well to our north, while
continued southerly flow off the Atlantic should drive some amount
of upglide and associated stratiform precip.  All the global models
now pick up on a least the early-stage development of a CAD event
by Sunday evening, though the GFS remains the most aggressive as
in previous runs.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EDT Thursday: The GFS, and now the ECMWF as well,
are picking up on the development of a largely in situ CAD
event by Monday.  Consequently, expecting significantly decreased
temperatures on Monday, likely well below normal, as precipitation
continues throughout Sunday night and Monday.

The arrival of Fred will dictate what happens next.  As of Tuesday
afternoon, there's still a decent amount of model spread, with
the GFS allowing Fred to fizzle and die over the Gulf Coast,
where the ECMWF and CMC depict some variation on Fred moving
through Georgia and into the western Carolinas.  The latter
scenario could bring substantial rainfall to the CWA beginning
Monday night and persisting through Tuesday; the GFS solution, by
contrast, results in drastically lower QPF totals.  Any solution
at this point will likely result in some hydro threat - as days
of widespread rainfall will have produced high stream levels and
elevated soil moisture, priming the environment for flooding.
The latest ECMWF dialed back QPF for the Blue Ridge Escarpment
from 8"+ totals to a more reasonable 4-6" storm total QPF, which
still seems a bit more reasonable.  In any case, confidence is
low in the exact track and local effects of Fred, and likely will
remain so for a least the next couple forecast packages.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Diurnally-driven showers and thunderstorms
have impacted the CFWA this afternoon/evening and will continue
through sunset, with the best coverage over the higher terrain. KHKY
and the vicinity of KAVL have already received showers and
thunderstorms today. Overall, the latest guidance continues to
depict less coverage than yesterday, largely due to less
instability, but still enough to keep TEMPOS and/or VCTS at all
sites. Still expecting the Piedmont sites to have a later start with
convection compared to the last couple of days. Whatever convection
does develop should dissipate fairly quickly this evening with skies
clearing out later tonight. Winds will be light through the period
and continue to favor a SWLY direction, except around tstms. The
potential for fog and/or low stratus will be similar again overnight
and tomorrow morning, with the best chances for restrictions over
the usual mtn valleys including KAVL. PROB30s for TSRA will once
again be included at all terminals for Friday afternoon/evening due
to not much change in the overall synoptic pattern and typical
summertime convection expected once again.

Outlook: Diurnal convection remains in the fcst for the rest of
the week and into the weekend. Fog and low stratus will be possible
each morning, especially over mountain valleys and areas primed by
rainfall from the previous evening.

Confidence Table...

            22-04Z        04-10Z        10-16Z        16-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     Low   55%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
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...MPR
NEAR TERM...CAC/JPT
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...CAC/JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
756 PM EDT Thu Aug 12 2021

NCZ033-035>037-048>053-056>059-068>072-082-501>510-SCZ007>009-
012>014-019-140000-
Avery-Alexander-Iredell-Davie-Madison-Yancey-Mitchell-Swain-Haywood-
Buncombe-Catawba-Rowan-Graham-Northern Jackson-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-Spartanburg-Cherokee-York-Laurens-
Union SC-Chester-Greenwood-
756 PM EDT Thu Aug 12 2021

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

.DAY ONE...Tonight.

Storms have become more isolated this evening and should gradually
diminish after sunset. Main impacts with this isolated activity are
cloud-to-ground lightning and heavy rainfall. An isolated strong to
severe storm cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-018-026-028-029-NCZ062>065-SCZ001>006-010-011-140000-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Macon-Southern Jackson-
Transylvania-Henderson-Oconee Mountains-Pickens Mountains-
Greenville Mountains-Greater Oconee-Greater Pickens-
Greater Greenville-Anderson-Abbeville-
756 PM EDT Thu Aug 12 2021

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

.DAY ONE...Tonight.

Storms have become more isolated this evening and should gradually
diminish after sunset. Main impacts with this isolated activity are
cloud-to-ground lightning and heavy rainfall. An isolated strong to
severe storm cannot be ruled out.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Daily chances of showers and thunderstorms will continue for several
more days. A cold front will stall over the area Saturday or
Saturday night and linger through Monday, further enhancing the
development of precipitation. The remnants of Tropical Cyclone Fred
may move into the area early next week. Altogether, an increasing
threat of localized flash flooding is expected over the coming days,
especially in areas that receive multiple rounds of heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
518 PM EDT Thu Aug 12 2021

NCZ503-504-122145-
Burke Mountains NC-Greater Burke NC-
518 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northwestern Burke
County through 545 PM EDT...

At 518 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Morganton, or near Table Rock. 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...
Morganton, Glen Alpine, Table Rock, Lake James, Lake James State Park
and Oak Hill.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 3594 8178 3593 8178 3592 8175 3588 8171
      3586 8167 3572 8172 3574 8189 3578 8195
      3582 8196 3585 8192 3588 8191 3591 8191
      3593 8193 3595 8193
TIME...MOT...LOC 2118Z 184DEG 4KT 3581 8183

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

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
530 PM EDT Thu Aug 12 2021

NCZ037-057-122200-
Rowan NC-Davie NC-
530 PM EDT Thu Aug 12 2021

...Strong thunderstorms will impact portions of central Davie and
western Rowan Counties through 600 PM EDT...

At 530 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 8 miles east of Mocksville to 9 miles northwest
of Kannapolis. Movement was south at 5 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...
Mocksville, Salisbury, Bermuda Run, Cooleemee, Cleveland, Enochville,
Fork Church, Advance, Mount Ulla and Piedmont Research Station.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3589 8037 3588 8042 3587 8039 3585 8039
      3585 8042 3583 8043 3584 8047 3583 8049
      3579 8048 3577 8045 3574 8046 3572 8042
      3551 8069 3551 8074 3571 8076 3605 8045
      3601 8042 3599 8042 3596 8038
TIME...MOT...LOC 2130Z 346DEG 5KT 3588 8041 3561 8071

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

TDP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
547 PM EDT THU AUG 12 2021

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

0524 PM     TSTM WND DMG     TABLE ROCK              35.84N 81.81W
08/12/2021                   BURKE              NC   PUBLIC

            PUBLIC REPORTED LARGE TREE LIMBS/BRANCHES DOWN IN TABLE
            ROCK.

&&

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
612 PM EDT Thu Aug 12 2021

NCZ507>510-122245-
Greater Rutherford NC-Polk Mountains NC-Rutherford Mountains NC-
Eastern Polk NC-
612 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northwestern
Rutherford and northern Polk Counties through 645 PM EDT...

At 612 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles northwest of Rutherfordton, or 6 miles east of Lake Lure,
moving southwest at 5 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...
Rutherfordton, Lake Lure, Chimney Rock State Park, Shingle Hollow,
Green Hill, Thermal City, Union Mills and Lake Adger.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3552 8196 3530 8196 3535 8228 3552 8219
      3553 8217 3552 8216 3554 8206
TIME...MOT...LOC 2212Z 023DEG 5KT 3547 8210

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

TDP

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
618 PM EDT THU AUG 12 2021

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

0510 PM     TSTM WND DMG     1 NE MOUNT ULLA         35.67N 80.72W
08/12/2021                   ROWAN              NC   911 CALL CENTER

            911 CALL CENTER REPORTED TREE DOWN ON UMBERGER RD.

&&

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
813 PM EDT Thu Aug 12 2021

SCZ007-130045-
Spartanburg SC-
813 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northwestern
Spartanburg County through 845 PM EDT...

At 813 PM EDT, Doppler radar was tracking a strong thunderstorm 13
miles southeast of Columbus, or near Lake Bowen. 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...
Lake Bowen, Boiling Springs SC, Chesnee and Fingerville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3506 8212 3519 8215 3518 8188 3517 8186
      3504 8190
TIME...MOT...LOC 0013Z 181DEG 3KT 3513 8201

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

TDP