Severe Thunderstorm Warning 219, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1120 AM EDT Fri Jul 6 2018

.SYNOPSIS...
Warm and moist high pressure will persist across the area into
Friday. A stormy cold front will cross the region Friday afternoon
with cooler and drier air working in through the weekend. Mostly dry
conditions will persist into next with with a general warming trend
in store.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1110 am: the easterly flow regime ends today as a weakness in
the upper ridge develops and a northern stream short wave moves
southeast across the Mid-Atlantic. This pushes a cold front into the
area this afternoon with south to southwest low level flow
developing ahead of it. Moisture and forcing increase ahead of the
front and short wave. Convection should initially develop in
response to differential heating near the Blue Ridge over the next
1-2 hours, followed by expansion of coverage along the encroaching
boundary across our northern and western zones by mid/late
afternoon. Convection will then spread southeast across the area
through the afternoon into the evening ahead of the front and along
migrant outflow boundaries.

Moderate to strong instability develops but shear is relatively weak
even with a short wave and cold front. However, DCAPE values will
top out between 750 and 1000 J/kg and Surface Delta Theta-E values
will be high as well. The cold front, DCAPE, and Surface Delta
Theta-E could be enough to help create an environment favorable for
severe storms despite the otherwise marginal conditions. Also, shear
over cold pool-depth could be just enough to support some degree of
organization/clustering, which would enhance the downburst threat.
In addition to the severe potential, isolated areas of heavy
rainfall could develop as PW values are around 2 inches and storms
should be efficient rainfall producers. Highs will be
near-to-slightly above normal.

The front moves south of the area tonight. However, low level
moisture lingers across the area. The low level flow returns to an
easterly direction as high pressure begins building in from the
north. This will keep scattered showers across the area through the
night. Lows will be a little above normal.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 300 AM EDT Friday: A drying trend is on tap for the weekend as
a cold front is projected to be south of the area Saturday morning
with broad high pressure shifting eastward across the OH Valley and
into New England throughout the day. As the parent high shifts
further off to the ENE, models continue to suggest that a part of
the high will build back down across the Carolinas, allowing for a
summertime wedge to setup into Sunday. Though isolated showers and
thunderstorms are possible Saturday morning, have kept with the
inherited downward trend of lower end PoPs into Saturday afternoon
and evening, along with decreasing clouds. Expect Sunday to be dry
and filled with much more sunshine than on Saturday. With the wedge,
do anticipate lower temperatures and dewpoints, however, as with any
wedge, temperatures will be the most tricky part of the forecast.
Any earlier break in the clouds or longer-lingering cloud cover
could make or break forecasted temperatures. For now across the
Upstate and NW Piedmont, have kept with upper 70s to around 80
degrees for high temperatures on Saturday, and a few degrees warmer
into the lower 80s on Sunday as overnight lows hover in the 60s.
Across the mountains, anticipate overall 70s for high's, and into
the 50s for low's. Also will note that though both the GFS and ECMWF
are both suggesting a low pressure system off the Carolina coast,
with the wedge in place, do not anticipate this to affect us across
the western Carolinas and northeast GA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 315 AM EDT Friday: As the medium range forecast period picks
up for the beginning of the work week, expect the dry weather
pattern to continue as the summertime wedge retreats and ridge of
high pressure sets up across a good portion of the CONUS. Towards
the middle of the week, guidance suggests the breakdown of the ridge
as a weak shortwave moves overhead, eventually getting pulled into
the upper trough across the Northeast. During this in between phase,
flow aloft becomes NW and the potential for isolated convection
could not entirely be out of the question on Wednesday and Thursday.
However, model disagreement really grows midweek through the end of
the forecast period. The GFS does continue key in on a coastal low
which meanders just offshore of the Cape Fear region before being
guided up the eastern seaboard under the influence of the upper
trough. The ECMWF does not highlight this low feature nor the true
return to SW flow which is suggested by the GFS. Thus, have overall
kept with a dry trend through the medium range with the exception of
the aforementioned low end PoPs/potential for isolated convection
Wednesday and Thursday. High temperatures will warm throughout the
week, beginning in the mid to upper 80s and climbing into the mid
90s by Thursday (cooler across the mountains).

&&

.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Will see generally sct low VFR and bkn cirrus
through the morning after the mountain valley fog dissipates this
morning. Today looks to be more convectively active as a surface
front drops down from the NW late in the day. Winds pick up from the
SW through the day. Low VFR cigs develop by afternoon and continue
through the day. Convection may fire a bit earlier than usual.
However, the prime time for development of thunderstorms is still
during the afternoon. Have gone with a 4 hour TEMPO for the best
chance of storms based on the mesoscale model guidance. Have a
PROB30 to cover lingering convection during the evening. Winds turn
W to WNW as the front moves through during the afternoon. Winds then
go N to NE through the night as high pressure builds in. MVFR cigs
move in from the north overnight as well.

Outlook: A low cloud ceiling in the IFR to MVFR range continues
Saturday morning. Low clouds and showers may persist into Saturday
afternoon as the frontal boundary settles south of the region.
Unsettled conditions could linger through early next week in the
vicinity of the stalled or dissipating front.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     High  96%
KGSP       High 100%     High 100%     High 100%     High  97%
KAVL       High 100%     High 100%     High  98%     High  91%
KHKY       High 100%     High 100%     High 100%     High  91%
KGMU       High 100%     High 100%     High 100%     High  98%
KAND       High 100%     High 100%     High 100%     High  98%

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...DEO/SGL
NEAR TERM...JDL/RWH
SHORT TERM...SGL
LONG TERM...SGL
AVIATION...RWH

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
540 AM EDT Fri Jul 6 2018

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-070945-
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-
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-Chester-Greenwood-
540 AM EDT Fri Jul 6 2018

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

.DAY ONE...Today and Tonight.

Scattered thunderstorms today and tonight will produce cloud-to-
ground lightning and locally heavy rainfall. Stronger storms could
produce localized flooding and gusty winds.

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

..Saturday...No hazardous weather is expected at this time.
..Sunday...No hazardous weather is expected at this time.
..Monday...No hazardous weather is expected at this time.
..Tuesday...No hazardous weather is expected at this time.
..Wednesday...No hazardous weather is expected at this time.
..Thursday...No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1229 PM EDT FRI JUL 6 2018

GAZ010-NCZ062-063-SCZ001-061730-
Rabun GA-Southern Jackson NC-Macon NC-Oconee Mountains SC-
1229 PM EDT FRI JUL 6 2018

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN RABUN...
SOUTHEASTERN MACON...SOUTH CENTRAL JACKSON AND NORTHWESTERN OCONEE
COUNTIES UNTIL 130 PM EDT...

At 1228 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles north of Walhalla, or 7 miles southeast of Highlands, moving
southwest at 20 mph.

Locations to be impacted include...
Clayton, Mountain City, Oconee State Park, Black Rock Mountain State
Park, Highlands, Mountain Rest, Long Creek, Pine Mountain, Bad Creek
and Whiteside Mountain.

Wind gusts up to 40 mph and pea size hail 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 3509 8311 3496 8296 3473 8322 3490 8343
TIME...MOT...LOC 1628Z 046DEG 10KT 3498 8311

STUREY

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1237 PM EDT FRI JUL 6 2018

NCZ053-065-505-507-061730-
Buncombe NC-McDowell Mountains NC-Henderson NC-
Rutherford Mountains NC-
1237 PM EDT FRI JUL 6 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN MCDOWELL...WEST
CENTRAL RUTHERFORD...NORTHEASTERN HENDERSON AND SOUTHEASTERN BUNCOMBE
COUNTIES UNTIL 130 PM EDT...

At 1236 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles east of Downtown Asheville, or near Black Mountain, moving
south at 20 mph.

Locations to be impacted include...
Black Mountain, Swannanoa, Fairview In Buncombe County, Old Fort,
Chimney Rock State Park, Bat Cave, Montreat, Gerton and Edneyville.

Wind gusts up to 50 mph and pea size hail 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 3546 8214 3543 8216 3540 8219 3540 8225
      3539 8226 3541 8247 3565 8240 3568 8218
TIME...MOT...LOC 1636Z 354DEG 10KT 3560 8229

STUREY

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1246 PM EDT FRI JUL 6 2018

NCZ503>508-061715-
Greater Rutherford NC-McDowell Mountains NC-Burke Mountains NC-
Greater Burke NC-Rutherford Mountains NC-Eastern McDowell NC-
1246 PM EDT FRI JUL 6 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN MCDOWELL...NORTHERN
RUTHERFORD AND SOUTHWESTERN BURKE COUNTIES UNTIL 115 PM EDT...

At 1245 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles east of Marion, or near Lake James State Park, moving south at
20 mph.

Locations to be impacted include...
Marion, Morganton, Glen Alpine, Lake James State Park, Table Rock,
Lake James, South Mountains State Park, Nebo, Green Hill and Thermal
City.

Wind gusts up to 40 mph and pea size hail will be possible in these
areas.

LAT...LON 3553 8169 3538 8170 3540 8214 3541 8216
      3540 8218 3583 8201 3585 8179
TIME...MOT...LOC 1645Z 005DEG 16KT 3569 8192

WJM

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1256 PM EDT FRI JUL 6 2018

NCZ063-064-SCZ001-002-061730-
Transylvania NC-Southern Jackson NC-Pickens Mountains SC-
Oconee Mountains SC-
1256 PM EDT FRI JUL 6 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN TRANSYLVANIA...
SOUTHEASTERN JACKSON...NORTHWESTERN PICKENS AND NORTHEASTERN OCONEE
COUNTIES UNTIL 130 PM EDT...

At 1255 PM EDT, Doppler radar was tracking a strong thunderstorm 19
miles north of Walhalla, or 5 miles southeast of Cashiers, moving
south at 15 mph.

Locations to be impacted include...
Rosman, Cashiers, Salem, Lake Toxaway, Lake Keowee, Jocassee Gorges,
Lake Jocassee, Devils Fork State Park, Gorges State Park and Table
Rock State Park.

Wind gusts up to 40 mph and pea size hail will be possible in these
areas.

LAT...LON 3525 8286 3508 8273 3508 8275 3506 8276
      3505 8275 3506 8271 3494 8262 3488 8275
      3480 8313 3494 8313 3494 8311 3495 8313
      3499 8310 3504 8314 3511 8314
TIME...MOT...LOC 1655Z 356DEG 13KT 3506 8303

WJM