Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
341 AM EDT Wed Sep 8 2021

.SYNOPSIS...
A cold front is expected to cross our area from the northwest later
today into early Thursday and bring more widespread showers and
thunderstorms to the region. Drying high pressure will spread back
over the region in the front's wake and linger through the weekend
and into the first half of next week, while summertime conditions
make a return to the area as well.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 325 AM EDT Wednesday: Over the past hour or so, we have
seen a cluster of cells come together over Stephens, Franklin,
and Oconee Counties and produce a large cell that appears to
have come close to severe criteria based on RADAR signatures.
Otherwise, the rest of the CWA remains mostly quiet. Additional
isolated to sct convection will likely linger for a few more
hours, especially over the SLY upslope prone areas and far NE
Georgia. Stronger storms should be limited by the diminishing
instability, and heavier QPF should be limited by moderate storm
movement. Abundant cloud cover will help keep low temps about 3
to 5 degrees above normal over most areas. Mtn valley fog will
likely develop thru the morning hours with any breaks in the
clouds.

Otherwise, once any lingering morning showers fizzle out and cloud
cover thins a bit, guidance suggests robust instability will develop
during the afternoon, around the same time that the frontal zone
associated with upstream height falls is expected to move into the
fcst area. I kept likely PoPs across most of the Piedmont and the
SE half of our Upstate zones, where less morning clouds/showers are
anticipated early on. Solid chance PoPs are advertised elsewhere.
Deep-lyr shear still looks minimal wrt its potential to organized
storms, however, 0-3 km shear in the 15-25 kt range will likely be
enough to support clustering of cells along cold pools. Microbursts
will be possible in association with any clusters as well as with
single cell pulse storms. If the fcst CAPE profiles pan out, we
could see some larger hail from a few storms, especially over the
NC Piedmont. High temps are expected to top out a few degrees above
climatology today.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 115 AM EDT Wednesday: The frontal zone is expected to be
in the far eastern CFWA during the beginning portions of the
short-term. Leftover moisture along the boundary may warrant an
early morning shower or thunderstorm along and east of the I-77
corridor, but dry air advection behind the fropa will lead to
much drier conditions during the day Thursday as high pressure
slowly builds in from the west. The upper trough over the Great
Lakes and OH Valley will help push the frontal boundary eastward
as the axis of the upper trough slips past the CFWA Thursday
evening. The sfc pressure gradient tightens up slightly Thursday
into Thursday night and could lead to low-end breezy conditions,
especially in the High Country, but any wind gusts should subside
by Friday morning as the center of the sfc high sets up shop
over the central Appalachians. Mostly sunny and dry conditions will
prevail through Friday as a result. Anomalously lower thicknesses
will keep temperatures in check with near-normal values expected
through the forecast period for highs and a category below normal
for lows as good radiational cooling processes will be in store for
both Thursday and Friday nights.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 215 AM EDT Wednesday: Sfc high will hold steady over the
Mid-Atlantic Saturday, while sliding offshore by Sunday. This
will allow for a return flow to enter back into the CFWA, along
with rising heights from a deepening upper ridge over the central
CONUS. A warming and more humid trend will prevail in this set up
through the period, but the additional subsidence aloft will help
cap any shower and thunderstorm development through the early part
of next week. The next frontal boundary is shown encroaching the
area by the middle part of next week, according to the GFS. Model
guidance keep this away from the CFWA through the day seven, so
most of the extended will remain dry. There are some differences in
the global models. The GFS sags the frontal boundary with height
falls towards the area by next Wednesday and Thursday, while the
ECMWF develops a sub-tropical ridge over the Mid-Atlantic region
and keeps any type of frontal zone far north and west. Either way,
the CFWA will remain mostly dry while temperatures uptick slightly
each day as we introduce another round of summertime conditions
during the medium range.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and Elsewhere: We've been seeing some robust convective
cells develop over our southern Upstate zones, and some activity
coming up from the SW and moving into our NE Georgia zones. Sct
convection will likely continue through the overnight hours,
especially over the SLY upslope prone areas. Additional VCSH
and/or TEMPOs for SHRA and/or TSRA may be needed through the
overnight and into the morning, mainly across the Upstate sites
and near KAVL, with KAND already carrying a TEMPO for TSRA for
the first couple hours of the period from 06 to 08z. Signals
remain mixed wrt the potential for early morning fog/low stratus,
but any breaks in the clouds will likely permit LIFR conditions
to develop quickly over the mtn valleys and around KAVL. Winds
will be mainly light and SLY to SWLY for the bulk of the period,
but with an uptick in speed to about 10kt with some low-end gusts
this afternoon. I kept the PROB30s for convective chances for
the afternoon/evening hours with the approach of the front from
the NW. Most of the precip should be moving east of our fcst area
as the taf period ends at 06z.

Outlook: Generally fair weather and high pressure is expected
on Thursday in the wake of the frontal passage. The fair wx will
likely persist thru the weekend and into early next week. Mtn
valley fog and low stratus will remain possible each morning.

&&

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

&&

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

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
622 AM EDT Wed Sep 8 2021

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>064-SCZ001-002-
004-005-010>012-019-091030-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Graham-Northern Jackson-Macon-
Southern Jackson-Transylvania-Oconee Mountains-Pickens Mountains-
Greater Oconee-Greater Pickens-Anderson-Abbeville-Laurens-Greenwood-
622 AM EDT Wed Sep 8 2021

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

.DAY ONE...Today and tonight.

Scattered showers and thunderstorms will develop this afternoon and
evening. The main threats will be cloud-to-ground lightning, heavy
downpours, and gusty winds.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ035>037-056-057-065-068>072-082-501>510-SCZ003-006>009-013-014-
091030-
Alexander-Iredell-Davie-Catawba-Rowan-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-Greenville Mountains-Greater Greenville-
Spartanburg-Cherokee-York-Union SC-Chester-
622 AM EDT Wed Sep 8 2021

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

.DAY ONE...Today and tonight.

Strong to severe thunderstorms will be possible this afternoon and
evening. The main threats will be cloud-to-ground lightning, damaging
winds, and isolated large hail.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
501 AM EDT Wed Sep 8 2021

SCZ006-010-012-080930-
Laurens SC-Anderson SC-Greater Greenville SC-
501 AM EDT Wed Sep 8 2021

...A THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT NORTHWESTERN
LAURENS...SOUTHEASTERN GREENVILLE AND EAST CENTRAL ANDERSON COUNTIES
UNTIL 530 AM EDT...

At 501 AM EDT, Doppler radar was tracking a thunderstorm with intense
lightning 13 miles northwest of Laurens, or 5 miles south of Fountain
Inn, moving northeast at 20 mph.

Locations to be impacted include...
Fountain Inn, Belton, Williamston, Honea Path, Gray Court,
Simpsonville, West Pelzer, Fork Shoals, Princeton and Hickory Tavern.

In addition to intense lightning, 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.

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 3461 8255 3478 8214 3475 8212 3475 8211
      3472 8208 3472 8206 3470 8207 3466 8200
      3461 8194 3447 8231 3448 8231 3448 8232
      3445 8236 3442 8245
TIME...MOT...LOC 0901Z 223DEG 17KT 3462 8222

CAC

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
505 AM EDT Wed Sep 8 2021

SCZ010-011-080930-
Anderson SC-Abbeville SC-
505 AM EDT Wed Sep 8 2021

...A THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT SOUTHEASTERN
ANDERSON AND NORTHWESTERN ABBEVILLE COUNTIES UNTIL 530 AM EDT...

At 505 AM EDT, Doppler radar was tracking a thunderstorm with intense
lightning 9 miles south of Anderson, or near Starr, moving east at 25
mph.

Locations to be impacted include...
Anderson, Homeland Park, Iva, Lake Secession, Starr, Anderson
Airport, Belton, Antreville and Broadway Lake.

In addition to intense lightning, 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.

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 3427 8275 3429 8277 3446 8280 3457 8252
      3429 8238 3426 8275
TIME...MOT...LOC 0905Z 262DEG 24KT 3438 8264

CAC

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
515 AM EDT Wed Sep 8 2021

SCZ003-006-007-012-081000-
Laurens SC-Greenville Mountains SC-Spartanburg SC-
Greater Greenville SC-
515 AM EDT Wed Sep 8 2021

...THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT NORTHWESTERN
LAURENS...EASTERN GREENVILLE AND SPARTANBURG COUNTIES UNTIL 600 AM
EDT...

At 515 AM EDT, Doppler radar indicated thunderstorms with intense
lightning along a line extending from 10 miles northeast of
Greenville Downtown to 13 miles west of Laurens, and moving northeast
at 15 mph.

Locations to be impacted include...
Spartanburg, Greenville Downtown, Greenville Eastside, Greer,
Mauldin, Taylors, Simpsonville, Five Forks, Fountain Inn and Boiling
Springs SC.

In addition to intense lightning, 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.

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 3450 8234 3505 8238 3519 8211 3519 8197
      3463 8188 3448 8231
TIME...MOT...LOC 0915Z 236DEG 14KT 3497 8227 3457 8225

CAC

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
538 AM EDT Wed Sep 8 2021

SCZ006>008-012-013-081030-
Cherokee SC-Laurens SC-Union SC-Spartanburg SC-Greater Greenville SC-
538 AM EDT Wed Sep 8 2021

...THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT NORTHERN
LAURENS...SOUTHEASTERN GREENVILLE...SPARTANBURG...CHEROKEE AND
NORTHWESTERN UNION COUNTIES UNTIL 630 AM EDT...

At 538 AM EDT, Doppler radar indicated thunderstorms with intense
lightning along a line extending from 4 miles north of Spartanburg to
9 miles west of Laurens, and moving east at 20 mph.

Locations to be impacted include...
Spartanburg, Gaffney, Laurens, Fountain Inn, Boiling Springs SC,
Woodruff, Pacolet, Cowpens, Blacksburg and Mayo.

In addition to intense lightning, 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.

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 3446 8230 3447 8232 3507 8204 3518 8167
      3517 8149 3457 8175 3445 8229
TIME...MOT...LOC 0938Z 248DEG 16KT 3500 8195 3452 8219

CAC

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