Severe Thunderstorm Warning 276, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
453 PM EDT Tue Aug 7 2018

.SYNOPSIS...
Weak high pressure will persist over the area into Wednesday. Then
a cold front will approach from the northwest and settle just
southeast of the area by Thursday. Seasonally warm temperatures and
scattered to numerous afternoon and evening showers and
thunderstorms will continue through the end of the week. The front
will persist in the vicinity through the weekend, with deeper
moisture returning from the south.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 4:45p EDT Tuesday:  Updated forecast to account for near term
convective trends.  Activity is fairly widely scattered and has been
declining earlier than usual over the last hour.  Blend of CAMs was
used as basis for POPs in first 6 hours.  Some fairly strong
updrafts have been seen so far this evening, with some continuing
chance for severe hail or wind, especially with cluster moving
southeast out of Pickens/Northern Greenville Counties.

A seasonably weak pressure field exists over the Southeast, with a
lobe of the Bermuda High extending onshore, while a trough extends
down the northern half of the Eastern Seaboard. A corresponding low-
amplitude upper ridge is present overhead, with light southwesterly
winds. Dewpoints remain exceptionally high at many obs sites, in the
lower to mid 70s, but may mix out a bit in the next couple of hours.
As has occurred the past couple of days, SBCAPE values have shot up
past 2500 J/kg, and storms fired over the mountain ridges around
noon.

Flat upper ridging will prevail over the region tonight into
Wednesday. As the upper trough advects east the flow becomes more
zonal, but heights do not fall appreciably across the Carolinas
or north Georgia. Low-level flow thus responds little and remains
west-southwesterly. In advance of the cold front moving thru the
Ohio/Tenn valleys, the trough east of the mountains does become a
bit better defined during the day Wed. Lapse rates manage to improve
a wee bit, and under slightly warmer sfc conditions, SBCAPE values
are progged to be a little higher at peak heating Wed. Given the
trough and better instability, we will advertise likely PoPs over
the mountains and chance values in the Piedmont. Height contours do
become a little better packed aloft tomorrow, and accordingly 0-6km
and 0-3km shear are slightly better. However, those are not strong
enough to suggest a significant enhancement to severe threat beyond
that posed by the large SBCAPE and marginally strong sfc-midlevel
delta-theta-E. Max temps will be normal across most of the area,
but perhaps a category above in the lower Piedmont zones.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 210 pm Tuesday: Broad upper trough will remain in place across
much of the East through the period, with attendant weak frontal
zone and associated deep moisture plume expected to ooze into the
forecast area through the end of the week. As such, very typical
mid-summer weather is expected to end the week, with much of the
area expected to see near-normal temps and near-climo pops for
primarily diurnal convection through the period. A possible
exception to this trend will be the NC mtns, particularly closer to
the TN border, where pops are advertised in the 50-60% range Thu and
Fri afternoon/evening to account for potential impacts from
convection developing along the frontal zone across the TN Valley
and wandering into the southern Appalachians by the end of the day.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 145 PM EDT Tuesday: An upper trough will close off into a low
over the Great Lakes over the weekend. The models are in decent
agreement on the depth and position of the low, but the GFS is just
a little SW of the ECMWF and more elongated N-S. Overall, the
differences do not have much impact on our sensible weather
forecast. A frontal boundary will remain draped across the
Southeast, from the Arklatex region thru the I-85 corridor of the
Carolinas. This should be a focus for enhanced convective coverage
thru the weekend, still mostly diurnally driven. The upper low will
quickly pivot NE and allow another front to drop in from the NW.
This front should push thru by Tuesday and bring some drier air into
the CWFA. The highest PoPs look to be Sunday and Monday, with
possibly a dry day on Tuesday. Temps will be near to slightly below
normal for afternoon highs, but still above normal for overnight
lows due to the expected enhanced moisture across the area. The 12z
Guidance doesn't seem to be hinting at much of a widespread heavy
rain threat. Although, isolated excessive rainfall/flooding will be
possible thanks to our we antecedent conditions.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Isolated to scattered TSRA across the region
this aftn into early evening in a typical mid-summer regime. The
chance is small enough to mention as VCSH/VCTS today, except at
KAVL due to its proximity to the rugged terrain. Light SW winds are
mainly expected except at KAVL where they will tend to be a bit more
NW. Any storm will be capable of gusty outflows and brief WSHFTs,
though the risk of strong to severe wind is small. Following the
dissolution of diurnal convection, the main concerns tonight will
be IFR mountain valley fog and patchy MVFR fog in the Piedmont,
though impacts are expected to be relatively brief and close
to daybreak. TSRA chances are a bit better at all sites on Wed,
after noon.

Outlook: Typical mid-summer conditions are fcst the next several
days. Diurnal, scattered thunderstorms will continue mainly
in the afternoons, with coverage tending to increase toward the
weekend. Associated morning restrictions will be possible each day,
especially in mountain valleys.

Confidence Table...

            21-03z        03-09Z        09-15Z        15-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High 100%     High 100%     High  83%     High 100%
KAND       High 100%     High 100%     High  91%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

&&

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

&&

SYNOPSIS...ARK
NEAR TERM...Wimberley/WJM
SHORT TERM...JDL
LONG TERM...ARK
AVIATION...Wimberley

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
502 AM EDT Tue Aug 7 2018

NCZ033-048>053-058-059-062>065-501-503-505-507-509-080915-
Avery-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Graham-
Northern Jackson-Macon-Southern Jackson-Transylvania-Henderson-
Caldwell Mountains-Burke Mountains-McDowell Mountains-
Rutherford Mountains-Polk Mountains-
502 AM EDT Tue Aug 7 2018

This Hazardous Weather Outlook is for the mountains of western North
Carolina.

.DAY ONE...Today and tonight.

Scattered thunderstorms will develop this afternoon and evening. Any
of these thunderstorms may produce cloud-to-ground lightning, locally
heavy rainfall, and briefly gusty winds.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Thunderstorm coverage will increase from Wednesday onward, especially
during the afternoon and evening periods. Primary impacts will
include cloud-to-ground lightning, heavy rainfall, and gusty winds.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-502-504-
506-508-510-SCZ001>014-019-080915-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Iredell-
Davie-Catawba-Rowan-Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-
Union-Greater Caldwell-Greater Burke-Eastern McDowell-
Greater Rutherford-Eastern Polk-Oconee Mountains-Pickens Mountains-
Greenville Mountains-Greater Oconee-Greater Pickens-
Greater Greenville-Spartanburg-Cherokee-York-Anderson-Abbeville-
Laurens-Chester-Greenwood-
502 AM EDT Tue Aug 7 2018

This Hazardous Weather Outlook is for northeast Georgia, Upstate
South Carolina, and the foothills and piedmont of western North
Carolina.

.DAY ONE...Today and tonight.

Isolated to scattered thunderstorms will develop this afternoon and
evening. Any of these thunderstorms may produce cloud-to-ground
lightning, locally heavy rainfall, and briefly gusty winds.

In addition, Heat Index values will rise to between 95 and 100
degrees for much of the area this afternoon. |

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Thunderstorm coverage will increase from Wednesday onward, especially
during the afternoon and evening periods. The main impacts will
include cloud-to-ground lightning, heavy rainfall, and gusty
winds.

Heat Index values of 95 to 100 will be likely once again on Wednesday
and Thursday. A few lower piedmont locations may see values as high
as 102 on Wednesday afternoon.

.SPOTTER INFORMATION STATEMENT...

None.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
330 PM EDT TUE AUG 7 2018

NCZ506-508-072000-
Greater Rutherford NC-Eastern McDowell NC-
330 PM EDT TUE AUG 7 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
SOUTHEASTERN MCDOWELL AND NORTHEASTERN RUTHERFORD COUNTIES UNTIL 400
PM EDT...

At 330 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 8 miles south of Marion, moving east at 10 mph.

Locations to be impacted include...
Shingle Hollow, Thermal City, Glenwood, Fero, Dysartsville, Union
Mills, Sugar Hill and Sunshine.

In addition to intense lightning, wind gusts up to 45 mph and half
inch hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3558 8182 3558 8180 3559 8180 3559 8179
      3540 8183 3547 8211 3550 8210 3560 8203
      3562 8206 3566 8205 3566 8185
TIME...MOT...LOC 1930Z 279DEG 9KT 3557 8201

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
351 PM EDT TUE AUG 7 2018

SCZ002-003-072015-
Pickens Mountains SC-Greenville Mountains SC-
351 PM EDT TUE AUG 7 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
NORTHWESTERN GREENVILLE AND NORTHEASTERN PICKENS COUNTIES UNTIL 415
PM EDT...

At 351 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 13 miles northeast of Pickens, or near Caesars Head
State Park, moving east at 10 mph.

Locations to be impacted include...
Slater-Marietta, Tigerville, Table Rock State Park, Pleasant Ridge
State Park, Caesars Head State Park, Jones Gap State Park,
Pumpkintown and Cleveland.

In addition to intense lightning, wind gusts up to 45 mph and half
inch hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3499 8272 3512 8267 3512 8266 3513 8264
      3513 8263 3514 8261 3514 8260 3515 8257
      3514 8251 3513 8235 3501 8239 3497 8254
      3494 8261
TIME...MOT...LOC 1951Z 287DEG 9KT 3506 8261

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
400 PM EDT TUE AUG 7 2018

SCZ002-072030-
Pickens Mountains SC-
400 PM EDT TUE AUG 7 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
NORTHWESTERN PICKENS COUNTY UNTIL 430 PM EDT...

At 359 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 11 miles northwest of Pickens, or near Jocassee
Gorges, moving east at 10 mph.

Locations to be impacted include...
Table Rock State Park, Keowee Toxaway State Park, Jocassee Gorges,
Lake Jocassee, Lake Keowee, Sunset, Pumpkintown, Sassafras Mountain,
Nine Times and Rocky Bottom.

In addition to intense lightning, wind gusts up to 45 mph and half
inch hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3501 8293 3501 8291 3503 8292 3506 8289
      3509 8279 3508 8278 3507 8278 3507 8277
      3505 8275 3507 8259 3492 8265 3486 8280
      3491 8291 3494 8290 3495 8291 3496 8291
      3499 8294
TIME...MOT...LOC 1959Z 287DEG 9KT 3499 8285

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
401 PM EDT TUE AUG 7 2018

NCZ065-072030-
Henderson NC-
401 PM EDT TUE AUG 7 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
SOUTHEASTERN HENDERSON COUNTY UNTIL 430 PM EDT...

At 401 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 7 miles south of Hendersonville, or 4 miles
southwest of Flat Rock, moving southeast at 10 mph.

Locations to be impacted include...
Hendersonville, Flat Rock, Laurel Park, Saluda, Dupont State Forest,
Valley Hill, Tuxedo, Crab Creek and East Flat Rock.

In addition to intense lightning, wind gusts up to 45 mph and half
inch hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3528 8235 3524 8235 3524 8236 3520 8235
      3519 8236 3519 8238 3521 8239 3519 8242
      3517 8244 3516 8246 3518 8246 3517 8249
      3516 8250 3516 8255 3515 8257 3516 8259
      3520 8260 3533 8250
TIME...MOT...LOC 2001Z 302DEG 7KT 3522 8249

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
430 PM EDT TUE AUG 7 2018

SCZ002-003-005-006-072100-
Pickens Mountains SC-Greater Pickens SC-Greenville Mountains SC-
Greater Greenville SC-
430 PM EDT TUE AUG 7 2018

...A CLUSTER OF THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT
NORTHERN GREENVILLE AND PICKENS COUNTIES UNTIL 500 PM EDT...

At 430 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms with intense lightning along a line extending from
17 miles southwest of Columbus to 12 miles northwest of Greenville
Downtown to 10 miles west of Pickens, and moving southeast at 15 mph.

Locations to be impacted include...
Easley, Pickens, Greenville Downtown, Greer, Taylors, Berea,
Travelers Rest, Liberty, Slater-Marietta and Norris.

In addition to intense lightning, wind gusts up to 45 mph will be
possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3478 8289 3479 8288 3482 8290 3491 8290
      3497 8292 3512 8261 3513 8240 3507 8222
      3493 8222 3472 8282
TIME...MOT...LOC 2030Z 304DEG 11KT 3506 8241 3500 8252 3490 8289

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
511 PM EDT TUE AUG 7 2018

GAZ010-SCZ001-004-005-072145-
Rabun GA-Greater Pickens SC-Greater Oconee SC-Oconee Mountains SC-
511 PM EDT TUE AUG 7 2018

...STRONG THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT
SOUTHWESTERN RABUN...SOUTHERN PICKENS AND OCONEE COUNTIES UNTIL 545
PM EDT...

At 511 PM EDT, Doppler radar indicated strong thunderstorms with
intense lightning along a line extending from 8 miles north of Seneca
to 3 miles southwest of Walhalla to 9 miles north of Toccoa, and
moving east at 15 mph.

Locations to be impacted include...
Clemson, Seneca, Walhalla, Easley, Central, Liberty, Westminster,
Norris, Six Mile and Lake Rabun.

In addition to intense lightning, wind gusts up to 45 mph and pea
size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3485 8294 3485 8290 3481 8290 3484 8284
      3480 8252 3468 8278 3463 8283 3455 8311
      3458 8316 3461 8316 3461 8322 3468 8334
      3473 8338 3473 8341 3475 8343 3474 8345
      3480 8356
TIME...MOT...LOC 2111Z 286DEG 15KT 3481 8295 3473 8310 3472 8338

RWH