Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
249 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 1030 am EDT: A few showers have developed in the Lakelands
area of the Upstate had have updated pops accordingly. Otherwise,
grids are in pretty good shape this morning for a seasonally hot and
muggy day across the area with typical summertime pops mainly across
the mountains in the NW flow.

Otherwise, 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 today. Forcing from these vorticity lobes may be
better in the northern tier today, but moisture and instability will
be better in the southern half, and that is where the better chance
PoPs will be featured during peak heating as sbCAPE values climb to
2500+ J/kg. Initiation should get started near the mountains again,
especially the southern escarpment area, but with a secondary focus
along a weak lee surface trough. Maximum temperatures should be
comparable to yesterday.

Tropical System Henri will remain well east of the Carolinas today
through tonight, with no impact to the region expected. Otherwise,
any diurnal convection will die out quickly this evening, with
another night of patchy fog along with some dense fog in the
mountain valleys. Mins remain above climo.

&&

.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 /19Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR this afternoon, with some pockets of MVFR
Cu as convection is expected to begin firing this afternoon, but at
this time not widespread enough to introduce TEMPO; have left VCSH
in TAFs at this time. Expect typical mountain valley fog again
tonight with MVFR to IFR conditions expected again at KAVL. Slightly
better chances for afternoon convection Sunday but too early to
introduce PROB30 at this time. Winds are generally lgt/vrb in the
weak pressure pattern but by tomorrow should be favoring the S/SW.

Outlook: A typical, diurnal summertime convective pattern is
expected to prevail the rest of the weekend 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...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High  99%     High 100%     High 100%
KGSP       High 100%     High 100%     High  80%     High  92%
KAVL       High  93%     High 100%     Low   51%     Med   79%
KHKY       High 100%     High  95%     Med   79%     High  91%
KGMU       High 100%     High 100%     High  81%     High  89%
KAND       High 100%     High 100%     High  99%     High  82%

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...TDP
SHORT TERM...AP
LONG TERM...AP
AVIATION...TDP

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
239 PM EDT Sat Aug 21 2021

NCZ504>506-508-211930-
McDowell Mountains NC-Greater Rutherford NC-Greater Burke NC-
Eastern McDowell NC-
239 PM EDT Sat Aug 21 2021

...A THUNDERSTORM WILL IMPACT SOUTHEASTERN MCDOWELL...NORTH CENTRAL
RUTHERFORD AND SOUTHWESTERN BURKE COUNTIES UNTIL 330 PM EDT...

At 238 PM EDT, Doppler radar was tracking a thunderstorm near Marion,
moving southeast at 10 mph.

Locations to be impacted include...
Marion, Lake James State Park, Lake James, Nebo, Sugar Hill, Thermal
City, Pleasant Gardens, Glenwood, Fero and Dysartsville.

Very 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 3563 8215 3578 8202 3568 8174 3545 8192
TIME...MOT...LOC 1838Z 304DEG 8KT 3567 8202

JPT

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

NCZ065-509-SCZ003-212030-
Henderson NC-Polk Mountains NC-Greenville Mountains SC-
347 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of southeastern
Henderson, southwestern Polk and north central Greenville Counties
through 430 PM EDT...

At 346 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southwest of Hendersonville, or near Laurel Park, moving
southeast at 10 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...
Hendersonville, Flat Rock, Laurel Park, Saluda, Mountain Home, Dupont
State Forest, Valley Hill, Tuxedo, North Saluda Reservoir and Crab
Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3531 8228 3529 8229 3525 8228 3506 8244
      3522 8260 3526 8260 3526 8262 3528 8261
      3537 8252
TIME...MOT...LOC 1946Z 309DEG 8KT 3527 8250

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

JPT

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

NCZ064-SCZ001-002-005-212100-
Transylvania NC-Pickens Mountains SC-Greater Pickens SC-
Oconee Mountains SC-
409 PM EDT Sat Aug 21 2021

...A strong thunderstorm will impact portions of south central
Transylvania, northwestern Pickens and northeastern Oconee Counties
through 500 PM EDT...

At 409 PM EDT, Doppler radar was tracking a strong thunderstorm 13
miles northwest of Pickens, or 4 miles northeast of Lake Jocassee,
moving southeast at 15 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...
Pickens, Jocassee Gorges, Lake Jocassee, Devils Fork State Park,
Gorges State Park, Keowee Toxaway State Park, Table Rock State Park,
Liberty, Lake Keowee and Pumpkintown.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3514 8293 3508 8274 3507 8275 3507 8277
      3505 8275 3505 8272 3506 8271 3506 8267
      3504 8259 3501 8260 3501 8257 3479 8272
      3499 8302
TIME...MOT...LOC 2009Z 295DEG 14KT 3502 8287

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

JPT