Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
250 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 225 PM EDT Thursday: Expect another hot and muggy day as
the sub-tropical ridge remains dominant over the Southeast along
with a persistent Bermuda High sfc pattern. So once again, expect
another round of scattered afternoon showers and thunderstorms
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
mountain should be 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 /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Expect another round of diurnally-driven
showers and thunderstorms this afternoon/evening, with the best
coverage still expected over the higher terrain. 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 wrt 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.

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...

            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%     Med   61%     Med   77%
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...JPT
SHORT TERM...MPR
LONG TERM...MPR
AVIATION...JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
412 AM EDT Thu Aug 12 2021

NCZ033-035>037-048>053-056>059-068>072-082-501>510-SCZ007>009-
012>014-019-130815-
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-
412 AM EDT Thu Aug 12 2021

This Hazardous Weather Outlook is for portions of western North
Carolina and eastern 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, which may cause localized flash flooding. A few storms
will produce brief damaging wind gusts.

.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>006-010-011-130815-
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-
412 AM EDT Thu Aug 12 2021

This Hazardous Weather Outlook is for northeast Georgia, western
upstate South Carolina, and the southern mountains of North
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, which may cause localized flash flooding. A few storms
will produce brief damaging wind gusts.

.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.

Wimberley

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

NCZ064-121915-
Transylvania NC-
248 PM EDT Thu Aug 12 2021

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

At 248 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles west of Brevard, or 4 miles southwest of Looking Glass. 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, Rosman, Graveyard Fields, Looking Glass, Dupont State
Forest, Balsam Grove, Connestee, Cedar Mountain and Penrose.

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.

&&

LAT...LON 3541 8274 3516 8261 3511 8286 3525 8293
      3529 8292 3531 8288 3532 8285 3532 8283
      3533 8282 3534 8282 3535 8280 3538 8279
TIME...MOT...LOC 1848Z 246DEG 4KT 3523 8282

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

TDP

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

NCZ064-SCZ002-003-122000-
Transylvania NC-Pickens Mountains SC-Greenville Mountains SC-
323 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of southeastern
Transylvania, northwestern Greenville and northwestern Pickens
Counties through 400 PM EDT...

At 323 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles south of Brevard, or near Rosman. 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...
Rosman, Table Rock State Park, Caesars Head State Park, Gorges State
Park, Dupont State Forest, Lake Jocassee, Jocassee Gorges, Balsam
Grove, Connestee and Sassafras Mountain.

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.

&&

LAT...LON 3525 8290 3516 8259 3499 8272 3504 8290
      3505 8291 3505 8293
TIME...MOT...LOC 1923Z 200DEG 3KT 3509 8280

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

TDP

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

NCZ056-502-504-122015-
Greater Burke NC-Greater Caldwell NC-Catawba NC-
345 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northwestern
Catawba, southeastern Caldwell and southeastern Burke Counties
through 415 PM EDT...

At 345 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Hickory, or over Connelly Springs. 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...
Hickory, Longview, Sawmills, Granite Falls, Valdese, Hudson, Icard,
Hildebran, Connelly Springs and Rutherford College.

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.

&&

LAT...LON 3563 8152 3580 8160 3592 8140 3566 8127
TIME...MOT...LOC 1945Z 248DEG 3KT 3575 8148

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

TDP

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

NCZ035-036-122015-
Iredell NC-Alexander NC-
347 PM EDT Thu Aug 12 2021

...Strong thunderstorms will impact portions of northern Alexander
and north central Iredell Counties through 415 PM EDT...

At 347 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 13 miles southeast of Wilkesboro to 5 miles
west of Taylorsville. Movement was northeast at 10 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...
Taylorsville, Love Valley, Vashti, Ellendale and Little River In
Alexander County.

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.

&&

LAT...LON 3605 8087 3594 8098 3588 8133 3592 8134
      3599 8133 3601 8131 3601 8129 3603 8127
      3604 8119 3603 8117 3604 8113 3603 8107
      3606 8098
TIME...MOT...LOC 1947Z 209DEG 10KT 3599 8104 3595 8127

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

TDP

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

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

0432 PM     TSTM WND DMG     5 SW MOUNT PLEASANT     35.35N 80.50W
08/12/2021                   CABARRUS           NC   PUBLIC

            PUBLIC REPORTED TREES DOWN AND A LARGE TREE BRANCH ON
            HOUSE ON CLUB VIEW DR.

&&

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

NCZ036-122045-
Iredell NC-
413 PM EDT Thu Aug 12 2021

...A strong thunderstorm will impact portions of northeastern Iredell
County through 445 PM EDT...

At 413 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles north of Statesville, or 4 miles southeast of Love Valley,
moving east 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...
Harmony, Love Valley, Union Grove, Turnersburg, Olin and Cool
Springs.

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.

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 3605 8089 3605 8076 3589 8071 3585 8071
      3583 8097 3595 8101 3596 8100 3599 8100
      3602 8102 3606 8091
TIME...MOT...LOC 2013Z 253DEG 6KT 3594 8092

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

TDP