Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
258 PM EDT Mon Jul 26 2021

.SYNOPSIS...
A weak cold front will move south across our area tonight and
Tuesday.  This will result in scattered to numerous showers and
thunderstorms with a few locations getting excessive rainfall in a
short time.  Expect drier and hotter conditions Wednesday through
Friday with high temperatures feeling like 100 degrees in the
piedmont.  A weak cold front will drop south this weekend cooling
temperatures to near normal.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 240 PM EDT Monday: Ridging remains entrenched over the western
U.S. with modest troughing over the Eastern Seaboard.  The wind
maximum is well to our north, with the Carolinas situated beneath
a comparatively relaxed wind pattern.  Meanwhile, a persistent
Bermuda high sits over the western Atlantic, and continues to
dominate surface flow, pumping moisture into areas east of the
Appalachians.  A weak shortwave crosses the region this afternoon,
inducing minor height falls and providing weak QG forcing.  At the
surface, the attendant cold front is already crossing the CWA,
generating convective activity as it encounters moderately-unstable,
moisture-rich air across the foothills.  Afternoon PWATs exceed 2"
across much of the Piedmont/Upstate in the wake of several days'
worth of southerly flow and moisture advection off the Atlantic
coast, so convection should have no trouble continuing well into
this evening.  CAMs favor increased SBCAPE toward the south, over
the southern Appalachians, SC Upstate and perhaps the southern
Piedmont of NC.

Slightly higher-than-anticipated effective shear across the
Carolinas means that a few stray severe cells cannot be ruled out
this afternoon, but as convection continues, the primary threat
will be heavy rainfall.  MBE velocities won't exceed 5kts, and
warm cloud depth will crest 12 kft for several hours.  Already, a
few backbuilding cells have been detected on radar, so this may be
the trend for the next few hours.  The HREF's probability-matched
mean depicts upwards of an inch of QPF in some spots across the
Upstate, and accordingly the WPC has placed the entire CWA under
a marginal risk for excessive rainfall.

Heights may tick up a tad on Tuesday, but with the weakening
boundary stalling along or south of the I-85 corridor, we'll retain
the risk of widespread showers, especially across the southern
tier of our counties.  CAMs suggest there will be a lull in precip
overnight tonight as upper forcing diminishes, before a rebound in
instability in the early afternoon tomorrow allows convection to
begin firing off again.  With SBCAPE values potentially exceeding
2500 J/kg, warm cloud depths at least 10-11 kft, and afternoon
LFCs even a bit lower than today's, convection will once again
be widespread, and these cells be will rain-producers similar
to today's.  The entire CWA remains in the WPC's marginal risk
for excessive rainfall tomorrow.  While confidence remains low
on the exact coverage and behavior of tomorrow's convection, the
CAMs agree that the most intense activity should have moved to our
south and east by late Tuesday evening, though scattered showers
will likely linger across the Upstate and perhaps the Southern
Piedmont through the end of the near term.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 245pm EDT Monday:  After rain trails off Tuesday night,
temperatures rebound on Wednesday following the clouds and rain that
kept temperatures in check on Tuesday.  Mid-90s are expected over
most of the foothills and Piedmont areas, and 80s to near 90 in the
mountains.  Weak FROPA on Tuesday only drops surface dewpoints a few
degrees over the mountains, and with continued high humidity, heat
index values will be on the sultry side a few degrees above observed
temperatures.  MLCAPE and convective forcing both are much reduced
Wed. and Thurs, and PWATs drastically decline to around 1.5" on
Wednesday, with low chances of rain or thunder.

General northwest flow aloft continues through Thursday and beyond
with weak surface high pressure giving light and somewhat variable
winds.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 2:45pm EDT Monday:  General northwest flow continues through
the extended with generally weak and variable surface winds and
occasional shortwave passages that enhance the chances for afternoon
thunder.  Persistent ridge keeps the central CONUS in its grip, with
a deep upper trough over the eastern half of the CONUS. There is
some chance for thunder, mostly in the afternoons, each day, with
the best chance for enchancement Saturday or Sunday as eastern CONUS
trough deepens considerably as it is reinforced by a large shortwave.

Temperatures across the area remain seasonally warm to hot, a few
degrees above normal, with slight cooling towards the end of the
week as eastern CONUS trough deepens.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: All TAF sites are VFR at this time.
Scattered clouds are increasing in coverage across the region
as a cold front approaches from the northwest.  This front has
already begun to spin up a line of showers and thunderstorms
over the northern foothills, and should continue to produce such
activity throughout the afternoon and evening.  All TAF sites
carry at least chance TSRA and vicinity thunder from 19Z until 00Z.
The most intense convection should diminish past this point in time,
though scattered showers should persist for several more hours into
the night.  There is increased confidence in the development of
IFR restrictions at KHKY, and LIFR restrictions at KAVL owing to
the development of fog/low stratus in the hours before sunrise.
All other sites remain VFR/MVFR into the morning.  We should
see scattered showers and storms tomorrow afternoon again, but
confidence is low enough on the timing and coverage to simply
carry VCSH and a few PROB30s.

Outlook: With the frontal boundary gradually becoming more diffuse
past Tuesday evening, drier air filters into the area and results in
a lull in activity Wednesday and Thursday.  Diurnally-drive pulse
thunderstorms should pick up again on Friday, along with a chance
for fog and low stratus Friday and Saturday morning.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High  94%     High  92%
KAVL       High 100%     High 100%     Med   66%     Med   77%
KHKY       High 100%     High  95%     High  82%     Med   77%
KGMU       High 100%     High  95%     High  98%     High  91%
KAND       High 100%     High 100%     High 100%     High  93%

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...DEO
NEAR TERM...MPR
SHORT TERM...WJM
LONG TERM...WJM
AVIATION...MPR

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
405 AM EDT Mon Jul 26 2021

NCZ036-037-057-270815-
Iredell-Davie-Rowan-
405 AM EDT Mon Jul 26 2021

This Hazardous Weather Outlook is for piedmont North Carolina.

.DAY ONE...Today and tonight.

A backdoor cold front will allow for shower and thunderstorm
development this afternoon into this evening. The main hazards are
cloud- to-ground lighting, isolated strong to severe storms bringing
the potential for damaging wind gusts, and heavy downpours. Any
areas that repeatedly see heavy downpours could experience excessive
rainfall leading to the potential for isolated flooding or flash
flooding.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-018-026-028-029-NCZ033-035-048>053-056-058-059-062>065-
068>072-082-501>510-SCZ001>014-019-270815-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Alexander-
Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Catawba-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-
405 AM EDT Mon Jul 26 2021

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

.DAY ONE...Today and tonight.

A backdoor cold front will allow for shower and thunderstorm
development this afternoon into this evening. The main hazards are
cloud- to-ground lighting and heavy downpours. Any areas that
repeatedly see heavy downpours could experience excessive rainfall
leading to the potential for isolated flooding or flash flooding.
Isolated strong to severe thunderstorms cannot be ruled out. The main
potential impact from any strong to severe storm would be isolated
damaging wind gusts.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
438 PM EDT Mon Jul 26 2021

SCZ007-008-262115-
Cherokee SC-Spartanburg SC-
438 PM EDT Mon Jul 26 2021

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN SPARTANBURG AND
NORTHWESTERN CHEROKEE COUNTIES UNTIL 515 PM EDT...

At 437 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles southeast of Columbus, or over Lake Bowen, moving east at 20
mph.

Locations to be impacted include...
Spartanburg, Boiling Springs SC, Cowpens, Inman, Mayo, Chesnee,
Cowpens National Battlefield, Lake Bowen, USC Upstate and Campobello.

Wind gusts up to 40 mph 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 3503 8217 3519 8213 3518 8174 3493 8180
TIME...MOT...LOC 2037Z 280DEG 18KT 3511 8207

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
515 PM EDT Mon Jul 26 2021

SCZ006-007-012-262145-
Laurens SC-Spartanburg SC-Greater Greenville SC-
515 PM EDT Mon Jul 26 2021

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
NORTHWESTERN LAURENS...EAST CENTRAL GREENVILLE AND WEST CENTRAL
SPARTANBURG COUNTIES UNTIL 545 PM EDT...

At 515 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 11 miles east of Greenville Downtown, or near GSP
Airport, moving southeast at 20 mph.

Locations to be impacted include...
Greer, Taylors, Five Forks, Fountain Inn, Duncan, Lyman, Reidville,
GSP Airport, Moore and Wellford.

In addition to intense lightning, wind gusts up to 45 mph 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.

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 3490 8239 3504 8223 3485 8194 3466 8217
TIME...MOT...LOC 2115Z 316DEG 16KT 3488 8220

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
547 PM EDT Mon Jul 26 2021

SCZ007>009-012>014-262215-
York SC-Cherokee SC-Laurens SC-Union SC-Chester SC-Spartanburg SC-
547 PM EDT Mon Jul 26 2021

...STRONG THUNDERSTORMS WILL IMPACT CENTRAL LAURENS...NORTHWESTERN
CHESTER...SOUTHWESTERN YORK...SOUTHEASTERN SPARTANBURG...SOUTHEASTERN
CHEROKEE AND UNION COUNTIES UNTIL 615 PM EDT...

At 547 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 11 miles southeast of Gaffney to 4 miles west of
Union to 3 miles north of Laurens, and moving southeast at 15 mph.

Locations to be impacted include...
Laurens, Union, York, Monarch Mill, Buffalo, Jonesville, Lockhart,
Sharon, Hickory Grove and Rose Hill State Park.

Wind gusts up to 40 mph 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 3499 8113 3465 8154 3444 8204 3456 8221
      3474 8180 3503 8160
TIME...MOT...LOC 2147Z 292DEG 11KT 3494 8154 3471 8171 3455 8203

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
611 PM EDT Mon Jul 26 2021

NCZ071-SCZ009-012>014-262245-
Mecklenburg NC-York SC-Laurens SC-Union SC-Chester SC-
611 PM EDT Mon Jul 26 2021

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN MECKLENBURG...
SOUTHEASTERN LAURENS...NORTHWESTERN CHESTER...SOUTHEASTERN YORK AND
CENTRAL UNION COUNTIES UNTIL 645 PM EDT...

At 611 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 5 miles north of Indian Land to 7 miles east of
Laurens, and moving south at 10 mph.

Locations to be impacted include...
Rock Hill, Union, Chester, South Charlotte, Fort Mill, Clinton,
Pineville, Tega Cay, Newport and Lesslie.

Wind gusts up to 45 mph 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 3426 8193 3453 8198 3518 8082 3507 8072
      3500 8084 3507 8091 3492 8086 3481 8089
      3457 8135 3457 8142 3453 8143 3446 8155
      3453 8164 3437 8178
TIME...MOT...LOC 2211Z 348DEG 10KT 3508 8088 3450 8189

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
620 PM EDT Mon Jul 26 2021

GAZ028-SCZ010-262245-
Hart GA-Anderson SC-
620 PM EDT Mon Jul 26 2021

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN HART AND CENTRAL
ANDERSON COUNTIES UNTIL 645 PM EDT...

At 620 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles southwest of Anderson, or near Lake Hartwell, moving southeast
at 15 mph.

Locations to be impacted include...
Anderson, Homeland Park, Starr, Anderson Airport, Lake Hartwell, Reed
Creek, Northlake, Broadway Lake and Sadlers Creek State Park.

Wind gusts up to 40 mph 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 3446 8292 3459 8273 3444 8254 3428 8280
TIME...MOT...LOC 2220Z 322DEG 11KT 3446 8279

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
645 PM EDT Mon Jul 26 2021

GAZ028-029-SCZ010-262315-
Elbert GA-Hart GA-Anderson SC-
645 PM EDT Mon Jul 26 2021

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL ELBERT...HART AND
SOUTHWESTERN ANDERSON COUNTIES UNTIL 715 PM EDT...

At 645 PM EDT, Doppler radar was tracking a strong thunderstorm near
Hartwell, moving southeast at 15 mph.

Locations to be impacted include...
Hartwell, Reed Creek, Bowersville, Lake Hartwell, Dewy Rose, Rock
Branch, Nuberg and Sadlers Creek State Park.

Wind gusts up to 40 mph 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 3436 8308 3448 8291 3430 8267 3413 8293
TIME...MOT...LOC 2245Z 322DEG 11KT 3437 8294

ARK