Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
334 AM EDT Fri Aug 20 2021

.SYNOPSIS...
Scattered showers and thunderstorms will be in store today.
Subsidence aloft associated with a ridge of high pressure over the
south-central CONUS will slowly build eastward and should lead to
drier conditions over the weekend. The pattern will remain
relatively unchanged through the early part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 305 am EDT: A positively-tilted upper trough axis stretches
from the eastern Great Lakes to the base of the Southern
Appalachians early this morning. Meanwhile, Tropical System Henri
remains well east of the N Florida coast and is not expected to have
any impact on the forecast area. Across our region, the convection
allowing models have modest redevelopment of showers and embedded
thunderstorms arriving from eastern TN near daybreak. Regional
radars already show this development just west of the mountains, and
isolated to scattered coverage across the western NC mountains
appears reasonable this morning given a decent vorticity lobe
swinging through the trough into the southern Appalachians.
Anticipate any convection moving into the higher terrain to be
fairly weak given the limited early morning instability of just a
few hundred J/kg of sbCAPE. Fog will be the other issue through
daybreak given brief breaks in the mid clouds and very moist ground.
However, additional stratocumulus arriving from the west should
preclude widespread dense fog this morning. This is handled with an
SPS for patchy dense fog through daybreak.

After the morning activity wanes across the mountains, additional
scattered convection should once again fire diurnally off the
eastern slopes of the mountains as the forcing moves through aloft.
A punch of mid-level dry air could permit storms to strengthen and
produce some gusty winds. The H5 low will close off over the
Virginias tonight, with any lingering forcing east of the area.
Anticipate daytime maxes near climo, but nighttime mins 1 to 2
categories above climo.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 130 AM EDT Friday: Closed upper low will continue to meander
over the mid-Atlantic region on Saturday, while slowly pushing
east. This will influence the track of TS Henri as the storm
moves up the Gulf Stream on the eastern peripheral of the closed
low. This won't bode well along the East Coast with an enhanced rip
current threat and the potential for a direct hit near Cape Cod and
other parts along the New England Coast. As the upper low pushes
east, NW-ly flow aloft will filter into the region and cap PoPs to
slight/low chance, with ridgetop convergence as the main forcing
mechanism, which allows for the highest shower and thunderstorm
chance to stay mainly confined to the High Country. Weak lee
troughing at the surface could help initiate a few isolated showers
and thunderstorms outside of the mountains, but the overall coverage
will be relatively sparse with drier conditions settling into a
good portion of the CFWA. PWAT values should lower to near-normal
values during the forecast period, which in turn helps keep the
shower and thunderstorm coverage fairly low for much of the weekend.

Rising heights begin to enter the CFWA from the west Saturday into
Sunday as an upper ridge gradually deepens over the Southern Plains
and lower Mississippi Valley. With NW-ly already in place aloft,
the typical summertime diurnal convection coverage will be even
lower on Sunday compared to Saturday. Only chance PoPs will be in
the forecast east of the mountains on Sunday as more subsidence
aloft enters the western Carolinas and northeast Georgia. Only
isolated coverage is expected for higher elevations with ridgetop
convection as the main source for initiation, while most locations
remain mostly dry on Sunday. Temperatures during the short-term
period will be at or slightly above normal for both highs and lows
over the weekend.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 300 AM EDT Friday: The trough axis associated with the
closed upper low will begin its track offshore during the beginning
portions of the extended. Upper high will give its best effort to
nose into the southeastern CONUS, but ends up retrograding westward
instead as the flow aloft flattens out over the northern CONUS and
the Bermuda High pattern begins to control the overall synoptic
pattern in the Southeast. With high heights (590+ dm) expected
to linger over the CFWA, the environment will continue to remain
fairly capped with the exception of more ridgetop convection during
the early part of next week. PoPs should increase slightly each day
starting Tuesday as a return flow enters the area with the Bermuda
High setting up shop in its usual position. This will allow for
the usual diurnal convection to enter back into the forecast by
the middle part of next week. Sandwiched between two upper highs,
heights will remain high through much of the period, which means we
will essentially be stuck in a hot and humid airmass through most of
the medium range. The Bermuda High per model guidance should inch
closer to the Carolina coast than it normal does and introduces a
deeper Atlantic fetch. PWAT values will rise back to near 2.00" by
the latter half of the forecast period. Global models are showing
a weak tropical wave encroaching the Southeast by days 6/7, which
would only enhance overall PoPs. An uptick in PoPs will be evident
Wednesday and beyond due to the this setup, even without an open
tropical wave. Temperatures will be above normal through the middle
part of next week before a slight dropoff to near normal values by
the end of the period as the pattern becomes more active once again.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Any isolated thunderstorms arriving from the
west in the NC mountains overnight should remain west of KAVL. The
main concern through the early morning hours will be fog and low
stratus in places where the mid deck scatters, mainly across the
mountains and foothills. However, additional stratocumulus will
arrive from the west to mitigate these issues at times. This will
likely lead to mainly TEMPO IFR to LIFR conditions at times through
daybreak at all but KCLT where the mid clouds will persist. The
mountain convection should die out this morning, but with additional
scattered activity moving off the mountains and out across the
foothills and Piedmont this afternoon. This warrants a PROB30 TSRA
mention at all sites through late day. Expect light winds, mainly
northwesterly, but with some WSW flow at times in the western
Upstate with mixing today. Fog will return tonight with drier air
aloft over moist ground.

Outlook: A typical, diurnal summertime convective pattern is
expected to prevail this weekend into early next week, with coverage
scattered at best. Mtn valley low stratus and fog will be possible
each morning.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

SYNOPSIS...CAC
NEAR TERM...HG
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...HG

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
457 AM EDT Fri Aug 20 2021

GAZ010-017-018-026-028-029-NCZ035>037-056-057-062>065-068>072-082-
502-504-506>510-SCZ001>014-019-210900-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Iredell-
Davie-Catawba-Rowan-Macon-Southern Jackson-Transylvania-Henderson-
Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
Greater Caldwell-Greater Burke-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-
457 AM EDT Fri Aug 20 2021

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

.DAY ONE...Today and tonight.

Isolated to scattered showers and thunderstorms are expected this
afternoon/evening. The main threats will be cloud-to-ground
lightning, damaging winds, and localized flash flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ033-048>053-058-059-501-503-505-210900-
Avery-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Graham-
Northern Jackson-Caldwell Mountains-Burke Mountains-
McDowell Mountains-
457 AM EDT Fri Aug 20 2021

This Hazardous Weather Outlook is for western North Carolina.

.DAY ONE...Today and tonight.

Morning showers and thunderstorms will continue through daybreak and
possibly beyond. The main threats are cloud-to-ground lightning and
localized flash flooding.

Scattered to numerous showers and thunderstorms are expected this
afternoon/evening. The main threats will be cloud-to-ground
lightning, damaging winds, and localized flash flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
439 AM EDT Fri Aug 20 2021

NCZ033-200915-
Avery NC-
439 AM EDT Fri Aug 20 2021

...A SERIES OF HEAVY RAIN SHOWERS WILL IMPACT AVERY COUNTY UNTIL 515
AM EDT...

At 437 AM EDT, Doppler radar was tracking one in a series of heavy
rain showers 4 miles north of Newland, or near Elk Park, moving east
at 15 mph. Additional showers were redeveloping to the west.

Locations to be impacted include...
Newland, Banner Elk, Elk Park, Beech Mountain In Avery County, Sugar
Mountain, Seven Devils, Grandfather Mountain State Park, Blue Ridge
Parkway-Linville Falls To Grandfather, Minneapolis and Linville.

Very heavy rainfall rates up to one-half to one inch per hour will
be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy 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 3625 8190 3624 8190 3623 8191 3621 8190
      3619 8188 3619 8186 3616 8183 3611 8181
      3610 8178 3607 8174 3603 8176 3609 8208
      3611 8208 3613 8205 3612 8203 3626 8193
      3627 8189
TIME...MOT...LOC 0837Z 278DEG 13KT 3615 8195

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
444 AM EDT Fri Aug 20 2021

NCZ051-058-200930-
Graham NC-Swain NC-
444 AM EDT Fri Aug 20 2021

...A SERIES OF HEAVY RAIN SHOWERS WILL IMPACT SOUTHWESTERN SWAIN AND
GRAHAM COUNTIES UNTIL 530 AM EDT...

At 442 AM EDT, Doppler radar was tracking one is a series of heavy
rain showers 8 miles north of Robbinsville, or near Fontana Village,
moving east at 20 mph. Additional showers are redeveloping to the
west.

Locations to be impacted include...
Robbinsville, Town Of Santeetlah, Smoky Mountains-Fontana Area, Lake
Santeetlah, Fontana Lake, Fontana Village, Smoky Mountains-Twentymile
Creek, Stecoah, Nantahala and Cheoah.

Heavy rainfall rates of one-half to one inch per hour will be
possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy 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 3544 8399 3546 8396 3547 8392 3552 8388
      3553 8382 3556 8377 3557 8368 3554 8355
      3529 8363 3528 8368 3525 8370 3526 8371
      3525 8373 3536 8402 3539 8401 3541 8402
TIME...MOT...LOC 0842Z 284DEG 16KT 3544 8378

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
455 AM EDT Fri Aug 20 2021

NCZ048-200945-
Madison NC-
455 AM EDT Fri Aug 20 2021

...A SERIES OF HEAVY RAIN SHOWERS WILL IMPACT MADISON COUNTY UNTIL
545 AM EDT...

At 453 AM EDT, Doppler radar was tracking one in a series of heavy
rain showers 12 miles northwest of Marshall, or near Hot Springs,
moving southeast at 15 mph. The showers were redeveloping to the
west.

Locations to be impacted include...
Marshall, Hot Springs, Faust, Allenstand, Walnut, Luck, Wolf Ridge
and Spring Creek.

Heavy rainfall rates of one-half to one inch per hour will be
possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy 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 3603 8259 3600 8261 3597 8261 3595 8256
      3598 8251 3595 8248 3591 8249 3590 8247
      3569 8286 3582 8295 3584 8292 3587 8292
      3588 8290 3593 8292 3595 8287 3592 8282
      3593 8281 3597 8278 3600 8277 3606 8264
TIME...MOT...LOC 0853Z 305DEG 12KT 3592 8285

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
534 AM EDT Fri Aug 20 2021

NCZ033-201015-
Avery NC-
534 AM EDT Fri Aug 20 2021

...A SERIES OF HEAVY RAIN SHOWERS WILL IMPACT AVERY COUNTY UNTIL 615
AM EDT...

At 533 AM EDT, Doppler radar was tracking another in a series of
heavy rain showers, with embedded thunderstorms, 4 miles north of
Newland, or near Elk Park, moving southeast at 25 mph. Additional
showers continue to redevelop to the west.

Locations to be impacted include...
Newland, Banner Elk, Elk Park, Beech Mountain In Avery County,
Crossnore, Sugar Mountain, Seven Devils, Grandfather Mountain State
Park, Linville Falls and B.R. Parkway-Linville Falls To Grandfather.

Very heavy rainfall rates of one-half to one inch per hour will be
possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Very heavy 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 3627 8189 3623 8191 3621 8190 3619 8188
      3619 8186 3616 8183 3611 8181 3610 8178
      3607 8174 3599 8179 3597 8182 3598 8187
      3600 8190 3595 8195 3611 8207 3613 8205
      3612 8203 3629 8192
TIME...MOT...LOC 0933Z 304DEG 21KT 3615 8194

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
541 AM EDT Fri Aug 20 2021

NCZ048-201015-
Madison NC-
541 AM EDT Fri Aug 20 2021

...A SERIES OF HEAVY RAIN SHOWERS WILL IMPACT MADISON COUNTY UNTIL
615 AM EDT...

At 540 AM EDT, Doppler radar was tracking another in a series of
heavy rain showers 13 miles northwest of Marshall, or near Hot
Springs, moving southeast at 20 mph. The showers were redeveloping
to the west.

Locations to be impacted include...
Marshall, Mars Hill, Hot Springs, Allenstand, Walnut, Luck, Spring
Creek, Max Patch and Canto.

Very heavy rainfall rates up to one inch 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 3581 8247 3580 8253 3573 8267 3573 8271
      3572 8271 3570 8277 3569 8281 3570 8285
      3568 8288 3574 8292 3574 8295 3575 8296
      3579 8296 3584 8292 3587 8292 3588 8290
      3593 8292 3595 8287 3593 8281 3600 8277
TIME...MOT...LOC 0940Z 305DEG 18KT 3590 8289

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
625 AM EDT Fri Aug 20 2021

NCZ048-201115-
Madison NC-
625 AM EDT Fri Aug 20 2021

...A HEAVY RAIN SHOWER WILL IMPACT SOUTHWESTERN MADISON COUNTY UNTIL
715 AM EDT...

At 624 AM EDT, Doppler radar was tracking a heavy rain shower 10
miles west of Marshall, or 5 miles southwest of Hot Springs, moving
southeast at 15 mph.

Locations to be impacted include...
Marshall, Hot Springs, Walnut, Luck, Spring Creek, Max Patch and
Canto.

Very heavy rainfall rates up to one inch 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 3595 8285 3592 8282 3594 8280 3577 8260
      3574 8267 3573 8267 3573 8271 3572 8271
      3569 8281 3570 8285 3568 8289 3574 8292
      3575 8296 3579 8296 3584 8292 3587 8292
      3588 8290 3593 8292 3593 8290 3595 8287
TIME...MOT...LOC 1024Z 321DEG 13KT 3582 8287

HG