Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
254 PM EDT Thu Aug 6 2020

.SYNOPSIS...
Passing upper-level disturbances will produce greater than
typical coverage of showers and thunderstorms through Friday. A
return to more typical isolated to scattered summertime thunderstorm
activity is expected over the weekend as weak drying arrives from
the west. Moisture will gradually return late in the weekend through
the middle of next week to support a more active pattern once again.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 254 PM Thursday: Convection still trying to catch
up to the forecast, but no reason to think that it will not
happen...eventually. The CAMs are now suggesting that the bulk of
the convective activity will happen during the evening hours over
the wrn Piedmont and Upstate, while convection may carry on into
the late evening across the entire region. That seems reasonable
as it is what often happens on days with a late start. Still
think we also remain on track for scattered severe storms with a
wind damage threat, given sfc-based CAPE already around 2500 J/kg,
dCAPE above 800 J/kg, and some mid-level dry air seen on satellite
imagery. Temps were in good shape.

Persistence will be the rule for the weather and the forecast of
the same for the next 24 hours as the upper trof axis remains in
place to our west. Just like last night, we may keep showery precip
around parts of the forecast area for the better part of the tonight
period before it finally wanes in the pre-dawn hours. On Friday,
more of the same. Hard to say if there will be the same amount of
morning cloudiness that will delay the onset again, but the fcst
looks the same in terms of coverage that will go beyond climo in
the afternoon. The environment should be conducive to a few pulse
severe storms again as well, with sfc-based CAPE in the 2000 -
3000 J/kg range and sfc-delta Theta-e above 30 deg. Temps will be
near normal as well.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 1230 pm EDT Thursday: Deeper moisture and higher PWAT values
will be displaced off to our east this weekend as weak upper trough
axis translates east and fills.  Essentially, for the upcoming
weekend, wx conds are expected to be pretty typical of early August,
featuring a developing weaker flow regime, and seasonable humidity
levels.  Dirunally fired deeper convective chances will be close to
climo values with piedmont maximum apparent temperatures approaching
95 each day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 100 pm EDT Thursday: Still expectimg a weak westerly flow
regime with embedded weak s/wv's rippling thru to exist atop the SE
CONUS to start off the work week.  PWAT progs starting on Monday
depict a moisting trend after a weekend featuring below climo values.
Despite limited Gulf moisture fetch, expecting a daily uptick in
diurnal PoPs for showers and thunderstorms each day.

PoPs may increase further above climo Wednesday and Thursday as
moisture begins to pool over the region as a frontal boundary lays
out across the Mid-Atlantic to the north. Anticipate plenty of lower
90s Piedmont to upper 80s mountain valley max temperatures each
afternoon, with mins a degree or so above climo through the period.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and Elsewhere: A thunderstorm has formed near the KAVL
airport and it seems to be anchored to the side of Mt Pisgah,
so that was taken into account for that TAF. Extensive cloudiness
this morning has delayed the development of the deeper convection
outside the mtns, though. A cumulus field continues to develop
over the wrn Piedmont with bases right around 030, which could
result in a brief MVFR ceiling for the next hour or so before it
lifts to 035 or higher. Otherwise...VFR with a light wind that
has a southerly component. The CAMs are somewhat at odds as to
the timing of thunderstorms across the region, but agree that all
sites will be affected by one at SOME point through the evening
hours. Rather than mess with PROB30s that have to be resolved later,
the fcst goes straight to a TEMPO at all sites for some 4-hr window
in the evening hours. Any convection after that will be handled
with amendments, as it is possible the storms will persist into
the early morning hours. After some convective debris thins out,
guidance remains on the track of developing MVFR/IFR stratus and
fog before daybreak across much of the region. Several sites get
at least an MVFR restriction in ceiling and/or vis, but confidence
not really high enough to go IFR everywhere yet. Might be another
late initiation again on Friday, so only KCLT gets a thunderstorm
mention after 18Z. Southerly flow will also persist.

Outlook: Coverage of thunderstorms will be more isolated to
scattered during the afternoon and evening over the weekend. Morning
fog/stratus restrictions will also be possible, especially over
the usual mountain valleys. Diurnal storms will become more likely
again from Monday onward.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     High 100%     High  85%     High  90%
KGSP       High 100%     High  99%     Med   70%     High  84%
KAVL       High 100%     High  95%     Med   74%     High  83%
KHKY       High 100%     High  94%     Med   68%     Med   76%
KGMU       High 100%     High 100%     Med   72%     High  84%
KAND       High 100%     High 100%     Med   77%     High  84%

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...CSH
NEAR TERM...PM
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...PM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
408 AM EDT Thu Aug 6 2020

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-070815-
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-
408 AM EDT Thu Aug 6 2020

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

.DAY ONE...Today and tonight.

Numerous thunderstorms are expected to develop across the region this
afternoon and evening, with the most widespread coverage likely
occurring across western North Carolina. Any of these thunderstorms
will be capable of producing dangerous lightning, gusty winds, and
torrential downpours. Some of these storms may become severe, with
damaging wind gusts being the primary threat. Any locations
repeatedly affected by thunderstorms over a short period of time will
be prone to localized flash flooding from the heavy rainfall.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information about
observed severe weather to the NWS while following all local, state,
and CDC guidelines.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
224 PM EDT Thu Aug 6 2020

NCZ053-065-061900-
Buncombe NC-Henderson NC-
224 PM EDT Thu Aug 6 2020

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN HENDERSON AND SOUTH
CENTRAL BUNCOMBE COUNTIES UNTIL 300 PM EDT...

At 223 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles north of Hendersonville, or near Fletcher, moving northeast at
10 mph.

Locations to be impacted include...
Fletcher, Mountain Home, Asheville Airport, Fairview In Buncombe
County, Mills River and Edneyville.

Wind gusts up to 40 mph and pea size hail will be possible in these
areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

&&

LAT...LON 3535 8251 3543 8256 3552 8241 3541 8233
TIME...MOT...LOC 1823Z 242DEG 10KT 3542 8249

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
319 PM EDT Thu Aug 6 2020

NCZ071-072-082-062000-
Union NC-Cabarrus NC-Mecklenburg NC-
319 PM EDT Thu Aug 6 2020

...A CLUSTER OF THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT
CABARRUS...SOUTHEASTERN MECKLENBURG AND NORTH CENTRAL UNION COUNTIES
UNTIL 400 PM EDT...

At 318 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms with intense lightning along a line extending from 4
miles northeast of Downtown Concord to 6 miles northeast of Indian
Land, and moving northeast at 20 mph.

Locations to be impacted include...
Downtown Concord, South Charlotte, Matthews, Mint Hill, Mt Pleasant,
Midland, The Arboretum, Harrisburg, East Charlotte and Stallings.

In addition to intense lightning, wind gusts up to 40 mph and pea
size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

Frequent lightning is occurring with these storms. If outdoors, try
to get indoors or into a hard topped vehicle. Otherwise, stay away
from open areas and isolated high objects such as trees. When
indoors, stay away from windows and doors and avoid using wired
electronic devices. Do not take a shower or bath. Try to unplug
unnecessary appliances before the storms approach.

&&

LAT...LON 3521 8048 3519 8051 3518 8050 3505 8086
      3550 8052 3550 8030
TIME...MOT...LOC 1918Z 226DEG 18KT 3546 8054 3509 8081

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
321 PM EDT Thu Aug 6 2020

NCZ065-507-509-510-061945-
Henderson NC-Polk Mountains NC-Rutherford Mountains NC-
Eastern Polk NC-
321 PM EDT Thu Aug 6 2020

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT WESTERN
RUTHERFORD...EAST CENTRAL HENDERSON AND NORTHWESTERN POLK COUNTIES
UNTIL 345 PM EDT...

At 321 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 10 miles northwest of Columbus, or 4 miles south of
Bat Cave, moving east at 10 mph.

Locations to be impacted include...
Lake Lure, Chimney Rock Village, Chimney Rock State Park, Bat Cave
and Edneyville.

In addition to intense lightning, wind gusts up to 40 mph and pea
size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

Frequent lightning is occurring with this storm. If outdoors, try to
get indoors or into a hard topped vehicle. Otherwise, stay away from
open areas and isolated high objects such as trees. When indoors,
stay away from windows and doors and avoid using wired electronic
devices. Do not take a shower or bath. Try to unplug unnecessary
appliances before the storm approaches.

&&

LAT...LON 3541 8217 3540 8219 3535 8215 3534 8233
      3542 8236 3548 8220
TIME...MOT...LOC 1921Z 249DEG 11KT 3539 8228

KRENTZ