Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
752 PM EDT Sat Aug 21 2021

.SYNOPSIS...
An upper level low over the Mid-Atlantic states will gradually lift
northeast into New England this weekend into early next week while a
ridge of high pressure in the southern United States gradually
builds into the southeastern United States. This upper-level pattern
will lead to only isolated shower and thunderstorm activity this
weekend into early next week across northeast Georgia and the
western Carolinas. Meanwhile Hurricane Henri will remain out in the
western Atlantic tracking north towards New England throughout the
weekend.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 750 PM EDT: An H5 closed low center over the central
Appalachians will continue to spin north of the region, with various
spokes of vorticity moving through the southern Appalachians and
crossing the forecast area tonight and Sunday. Tropical System Henri
will remain well east of the Carolinas tonight, with no impact to
the region expected. Convection this evening will move east of the
area but some isolated showers may linger. Mountain valley fog and
stratus, some dense, will develop overnight. Patchy fog and low
clouds expected elsewhere. Lows will be a little above normal.

Fog burns off quickly Sunday but low clouds may linger through the
morning. Expect isolated to scattered diurnal convection again.
Highs will be a little above normal, unless the clouds are thicker
or linger longer which would keep highs in check.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 200 PM EDT Saturday: The overall synoptic pattern for the
short term has a closed low over the Mid-Atlantic region lifting
northeast towards New England and interacting with Hurricane Henri
as it gradually lifts away from the Carolinas. Meanwhile, a high
pressure system over the southern CONUS builds into the Southeastern
US while the Bermuda high in the Atlantic begins to build westward
towards the southeastern CONUS. The ridge to our west will lead to
increased subsidence and northwesterly flow Monday into Tuesday
across the western Carolinas and northeast Georgia. This ridge will
also help confine low to mid-level moisture to the Carolina coast,
keeping it well east of the forecast area throughout the short term
period. So, overall shower and thunderstorm chances early next week
should remain isolated in nature. Global models are in good
agreement in regards to drier conditions Monday, and have been
trending drier for Tuesday. Monday only have a slight chance for
PoPs across portions of the mtns, the far southeastern SC Upstate
and far southeastern NC Piedmont. Tuesday capped Pops to a slight
chance to low end chance. Monday and Tuesday will be much warmer
compared to this weekend and look like the warmest days of the week
next week. Highs should range from the low to mid 90s outside the
mtns with mid 80s to low 90s across the mtns. Higher elevations will
see slightly cooler highs. High temps early next week look about 5
to 10 degrees above climo.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 230 PM EDT Saturday: The western Carolinas and northeast
Georgia will be sandwiched between two high pressure systems
throughout much of the extended. The ridge of high pressure to our
west will retreat back west towards the beginning of the forecast
period while the Bermuda high to our east pushes further west
towards the Southeastern US. PWATs will increase each afternoon
Wednesday into Saturday thanks to the Bermuda high extending over
the area. PWAT values should be around 1.5 inches across the mtns
and 1.7 to 2.0 inches outside the mtns. Both the GFS and ECMWF
continue to show a weak tropical wave east of Florida on Wednesday.
The Bermuda high in the western Atlantic will help steer this
tropical wave towards the Southeast coast. The 12z GFS and ECMWF are
now in somewhat better agreement on the overall track of the
tropical wave, but not on the strength. The GFS keeps the tropical
wave closed while the ECMWF keeps the tropical wave open. Both
models now agree that the tropical wave will track across Florida
late Wednesday into Thursday, before tracking across the Deep South
while ridge of high pressure builds over the south-central East
Coast Friday into Saturday. Since the previous run of the ECMWF had
the tropical wave tracking into the Carolinas, confidence on where
this tropical wave will push inland, as well as the strength of the
wave, remains very low at this time. This tropical wave would lead
to increased shower and thunderstorm chances as well as cloud cover
for the CWA. As a result, high temps would be cooler through the
extended period. High temps Wednesday will remain a a few degrees
above climo, but should drop back to near climo Thursday into
Saturday.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
At KCLT and elsewhere: A shower or 2 will be close to KHKY and KAVL
early this evening. SC sites look to be convection free. KCLT is the
trouble spot where showers are moving toward the airfield from the
west. Has been some off and on lightning in the cell near KEHO. A
much stronger cell is dropping SSE from the north. Quite a bit of
lightning with this cell. Earlier movement looked to keep it east of
the airfield, but if motion turns more southerly, then TSRA in play.
Have kept it as SHRA in the TEMPO, but will monitor for AMD.

May be some off and on showers for the rest of the evening and
possibly overnight, but no thunder expected. Bigger concern is
potential for restrictions before daybreak. Guidance now firmly
suggesting at least IFR cigs and vsby, if not worse, for the
mountain valleys. Guidance also firmly suggesting low MVFR to
possibly even IFR cigs for the SC sites by daybreak. Fog less likely
there. MVFR fog expected at KCLT and KHKY with MVFR to even IFR cigs
possible, but the cigs are uncertain. Light and variable wind
expected.

Any fog should burn off quickly, but cig restrictions will linger
through the morning before lifting and scattering near noon. There
is enough of a chance of convection for afternoon PROB30s. Winds
should be light SW, with KAVL seeing N during the morning.

Outlook: A typical, diurnal summertime convective pattern is
expected to prevail through the middle of next week, with scattered
coverage at best. Mountain valley fog will be possible each morning,
as well as at sites that receive heavy rainfall the previous
afternoon.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     High 100%     High  94%     High  98%
KGSP       High 100%     High  85%     Med   71%     High  97%
KAVL       High  87%     Med   70%     High  84%     High  97%
KHKY       High  95%     Med   79%     High  88%     High  98%
KGMU       High 100%     High  89%     High  85%     High  98%
KAND       High 100%     High  95%     Med   78%     High  97%

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...AP
NEAR TERM...RWH/TDP
SHORT TERM...AP
LONG TERM...AP
AVIATION...RWH

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
401 PM EDT Sat Aug 21 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-222015-
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-
401 PM EDT Sat Aug 21 2021

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

.DAY ONE...Tonight.

Isolated to scattered showers and thunderstorms will continue into
this evening. The main threats will be cloud-to-ground lightning and
locally heavy rainfall. One or two storms may become strong to
severe.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

MPR

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
719 PM EDT Sat Aug 21 2021

SCZ007-008-013-220015-
Cherokee SC-Union SC-Spartanburg SC-
719 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of northeastern
Spartanburg, southern Cherokee and northern Union Counties through
815 PM EDT...

At 719 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles east of Spartanburg, or near Pacolet Mills, moving southeast at
15 mph.

HAZARD...Winds in excess of 40 mph and up to penny 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...
Spartanburg, Pacolet, Cowpens, Jonesville, Pacolet Mills, Croft State
Park, Cedar Springs, Thicketty, Saratt and Adamsburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3490 8193 3507 8185 3499 8148 3494 8149
      3494 8147 3493 8148 3491 8147 3490 8148
      3489 8147 3472 8155
TIME...MOT...LOC 2319Z 292DEG 14KT 3495 8180

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
722 PM EDT Sat Aug 21 2021

NCZ036-056-069-220000-
Iredell NC-Lincoln NC-Catawba NC-
722 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of eastern Catawba,
northeastern Lincoln and southern Iredell Counties through 800 PM
EDT...

At 721 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles southwest of Statesville, or near Catawba, moving southeast at
15 mph.

HAZARD...Winds in excess of 40 mph and up to 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...
Mooresville, Westport, Troutman, Claremont, Catawba, Lake Norman,
Lake Norman State Park, Denver, Lookout Shoals Lake and Sherrills
Ford.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3574 8117 3581 8098 3559 8075 3545 8109
TIME...MOT...LOC 2321Z 330DEG 11KT 3570 8103

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

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
748 PM EDT Sat Aug 21 2021

NCZ068>070-SCZ009-220030-
Gaston NC-Cleveland NC-Lincoln NC-York SC-
748 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of south central
Lincoln, southeastern Cleveland, western Gaston and northwestern York
Counties through 830 PM EDT...

At 747 PM EDT, Doppler radar was tracking a strong thunderstorm near
Shelby, moving east at 25 mph.

HAZARD...Winds in excess of 40 mph and small 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...
Gastonia, Shelby, Kings Mountain, Cherryville, Bessemer City, South
Gastonia, Dallas, High Shoals, Patterson Springs and Waco.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3511 8119 3516 8137 3517 8137 3516 8139
      3523 8164 3539 8161 3545 8113
TIME...MOT...LOC 2347Z 275DEG 20KT 3531 8151

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

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
901 PM EDT Sat Aug 21 2021

SCZ013-014-220145-
Union SC-Chester SC-
901 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of Chester and east
central Union Counties through 945 PM EDT...

At 901 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles southwest of Chester, or 5 miles northeast of Carlisle, moving
southeast at 20 mph.

HAZARD...Winds in excess of 40 mph and small 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...
Chester, Richburg, Chester State Park, Blackstock, Carlisle, Lowrys,
Leeds, Cornwell and Santuc.

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.

&&

LAT...LON 3456 8094 3454 8096 3457 8143 3464 8153
      3482 8142 3476 8091
TIME...MOT...LOC 0101Z 302DEG 19KT 3464 8140

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

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
922 PM EDT Sat Aug 21 2021

NCZ056-069-502-504-220200-
Lincoln NC-Greater Burke NC-Greater Caldwell NC-Catawba NC-
922 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of western Catawba,
north central Lincoln, southeastern Caldwell and southeastern Burke
Counties through 1000 PM EDT...

At 921 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles west of Hickory, or near Hildebran, moving southeast at 10 mph.

HAZARD...Winds in excess of 40 mph and small 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, Newton, St. Stephens, Conover, Longview, Sawmills, Granite
Falls, Icard, Hildebran and Connelly Springs.

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.

&&

LAT...LON 3576 8113 3548 8131 3567 8159 3583 8150
TIME...MOT...LOC 0121Z 294DEG 8KT 3570 8145

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

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
948 PM EDT Sat Aug 21 2021

NCZ082-SCZ009-014-220215-
Union NC-York SC-Chester SC-
948 PM EDT Sat Aug 21 2021

...A THUNDERSTORM WILL IMPACT SOUTHWESTERN UNION...EASTERN CHESTER
AND SOUTHEASTERN YORK COUNTIES UNTIL 1015 PM EDT...

At 948 PM EDT, Doppler radar was tracking a thunderstorm 8 miles west
of Lancaster, or near Fort Lawn, moving east at 25 mph.

Locations to be impacted include...
Rock Hill, Lesslie, Great Falls, Fort Lawn, Richburg, Andrew Jackson
State Park, Catawba, Fishing Creek Reservoir, Jaars and Edgemoor.

Heavy rainfall rates up to 2 inches per hour 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.

&&

LAT...LON 3482 8064 3482 8080 3484 8080 3484 8087
      3483 8090 3479 8088 3475 8088 3470 8086
      3464 8090 3456 8087 3454 8088 3455 8101
      3458 8114 3482 8118 3495 8107 3490 8088
      3485 8087 3485 8080 3488 8079 3484 8064
TIME...MOT...LOC 0148Z 283DEG 23KT 3469 8092

JPT