Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
238 PM EDT Wed Jul 12 2017

.SYNOPSIS...
Hot and humid conditions will persist the rest of the week, with
scattered to numerous afternoon and evening thunderstorms each day.
A cold front will move into the region from the northwest on
Saturday and stall in or near the forecast area through Sunday.
Another cold front will approach on Monday and move east of the area
area on Tuesday, with drier conditions arriving by the middle of
next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 230 PM EDT Wednesday: Very little change in the synoptic
fields through the near-term, with upper ridging over the Southeast
as well as Bermuda high ridging into the area. Nearly zonal flow
aloft just to our north will continue, with a weak impulse pushing
across the Upper Ohio Valley as we move into Thursday. Lee trough
already in place today will strengthen ever so slightly for tomorrow
as a slug of Gulf moisture lifts up into the Tennessee Valley. But
with overall very little change in the pattern, the focus will
remain on the heat (and humidity) as well as increasing chances of
afternoon convection.

For this afternoon, very weak cap due to slight warming just above
800mb is helping to keep mid-level lapse rates in check today,
though sbCAPEs are approaching 3000 J/kg as you push into the NC
Piedmont. With southerly/southwesterly low level flow and very
little flow aloft with the upper ridge, the typical orographic
component remains in place so we are seeing convection fire along
the Blue Ridge. Cannot rule out an isolated strong thunderstorm, but
primary concerns would be heavy rain and lightning. As we move into
tomorrow, bufr soundings indicate that we lose that warming just off
the surface (or at least part of it) with slightly steeper lapse
rates progged, and with the closer proximity of the upper dynamics,
expect more convection especially across the mountains tomorrow than
today. Marginal Risk remains well to our north for Day2 so still
mainly just generic pulse thunderstorms but have included likely
pops across the mountains, especially the Blue Ridge. And of course,
as is the case usually in the summer with diurnal convection, patchy
fog especially in mountain valleys can be expected tomorrow.

Other story remains the heat. At AFD time, we're still a couple of
degrees shy of afternoon MaxTs, but see no reason why we shouldn't
realize current forecast highs. With little change to the upper
pattern and continued WAA at the surface around the Bermuda high,
expect a slight uptick in temps tomorrow, ending up a couple of
degrees above seasonal normals. This MAY be tempered by the
increasing cloud cover, but with plentiful surface moisture expect
heat indices across the Piedmont to reach 100, maybe a degree or two
above. Still not advisory criteria but we've been kind of spoiled
this summer with average to below-average temps for the most part
(and remarkably few 90 degree days), so it's good for folks across
the area to still take any necessary heat precautions.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 210 PM EDT Wednesday: The ridge over the SE CONUS weakens on
Friday as a short wave trough moves into the Great lakes and OH
River Valley. A weak cold front approaches from the NW while the lee
trough across our area sharpens. This will lead to increased low
level convergence and moisture pooling. Although lapse rates are
relatively weak, instability again becomes moderate to strong. DCAPE
values remain high as well keeping the potential for very gusty
winds and isolated damaging downbursts with the strongest storms. PW
values also remain high continuing the isolated flooding threat.
Highs in the low to mid 90s outside of the mountains will combine
with dew points in the 70s for Heat Index values as high as 104.
Mountain valleys will see values around 90. Little relief from the
heat at night with lows in the low to mid 70s.

Good convective coverage continues Saturday, although the better
chances shift to areas outside of the mountains. A weak short wave
moves into the area bringing slightly cooler mid level temps and
slightly steeper lapse rates. The weak cold front moves into the
area keeping increased low level convergence and moisture pooling
over the area. Although surface temps will be a little cooler, the
moisture and steepening lapse rates keep moderate to strong
instability in place. Shear will increase as well but maxing out
near 20 kts. Still, with the continued high DCAPE values this could
lead to some organization or at least a better than isolated chance
of damaging downbursts. Continued high PW values will keep the
isolated flood threat in place. Although dew points in the lower 70s
remain common, temps will be a little cooler as mentioned above.
Maximum heat index values will top out near 100, with most locations
in the mid to upper 90s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 200 PM EDT Wednesday: The medium range begins Saturday night
amid longwave troughing over the eastern CONUS. A surface front will
likely be stalling across or very near to the forecast area at this
time, encouraging widespread showers and thunderstorms across the
forecast area. Heights will fall once again late in the day on
Sunday, providing forcing for scattered showers and thunderstorms
peaking in the afternoon hours once again. The upper trough sharpens
up on Monday, and with the surface front still stalled in or just
south of our forecast area, high end chances for showers and
thunderstorms were carried through the afternoon and evening.
Support for widespread lift will also be present as the RRQ of an
upper jet streak passes overhead late on Monday. Profiles do not
feature very plentiful CAPE or shear through the weekend and early
in the week, though precipitable water values will be near the daily
max over the weekend.

Another front will shift towards the area on Tuesday, just in time
to provide a focus for some diurnal shower and thunderstorm activity
once again. Deep layer moisture will be more limited on Tuesday,
however, as drier air and an upper high edge into our area. Dry air
will limit pops on Wednesday before another weak front approaches
the area on Thursday. Maximum and minimum temperatures will fall
to just below normal through the medium range period.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Scattered convection through the afternoon
may impact mainly KAVL have continued VCTS there. Chances not high
enough to include at other TAFs with generally SCT VFR Cu but cannot
rule out something isolated nearby. Expect at least MVFR
restrictions to develop in the mountain valleys overnight, probably
to affect KAVL and possibly KHKY, but could easily see another round
of LIFR and anything in between. Expect convection again Thursday
afternoon but generally after 18z for most sites; have introduced
PROB30 for KAVL. Otherwise S/SW winds 5-8kt this afternoon subsiding
overnight, picking back up Thursday.

Outlook: Diurnal convective chances will continue to rise through
Friday, as well as any morning fog in mountain valleys and where
convection occurs the previous afternoon.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     Med   67%     High  86%
KHKY       High 100%     High 100%     High  91%     High 100%
KGMU       High 100%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High  97%     High  94%

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...Carroll
NEAR TERM...TDP
SHORT TERM...RWH
LONG TERM...Carroll
AVIATION...TDP

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
456 AM EDT Wed Jul 12 2017

GAZ010-NCZ033-048>053-058-059-062>065-501-503-505-507-509-130900-
Rabun-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-
456 AM EDT Wed Jul 12 2017

This Hazardous Weather Outlook is for Rabun County in northeast
Georgia and the mountains of western North Carolina.

.DAY ONE...Today and Tonight.

Scattered thunderstorms will develop across the mountains this
afternoon and evening. The thunderstorms will move very slowly and
locally heavy rainfall could produce isolated flooding of low-lying
and poor drainage areas. Otherwise, expect cloud-to-ground lighting
and briefly gusty winds in and near any thunderstorms that develop.

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

..Thursday...No hazardous weather is expected at this time.
..Friday...No hazardous weather is expected at this time.
..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.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ017-018-026-028-029-NCZ035>037-056-057-068>072-082-502-504-506-
508-510-SCZ001>014-019-130900-
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-
456 AM EDT Wed Jul 12 2017

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

.DAY ONE...Today and Tonight.

Isolated to scattered thunderstorms will develop across the region
this afternoon and evening. The thunderstorms will move very slowly
and locally heavy rainfall could produce isolated flooding of low-
lying and poor drainage areas. Otherwise, expect cloud-to-ground
lighting and briefly gusty winds in and near any thunderstorms that
develop. Also, hot and humid conditions may produce Heat Index values
of 100 to 102 degrees this afternoon.

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

..Thursday...Excessive heat possible. Afternoon Heat Index values
between 100 and 104 are expected.
..Friday...Excessive heat possible. Afternoon Heat Index values
between 100 and 105 are possible.
..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.

.SPOTTER INFORMATION STATEMENT...

None.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
301 PM EDT WED JUL 12 2017

NCZ064-065-121930-
Transylvania NC-Henderson NC-
301 PM EDT WED JUL 12 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN TRANSYLVANIA AND
SOUTH CENTRAL HENDERSON COUNTIES UNTIL 330 PM EDT...

At 300 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles southeast of Brevard, or over Dupont State Forest. This storm
was drifting slowly to the east northeast.

Locations to be impacted include...
Brevard, Laurel Park, Dupont State Forest, Flat Rock, Valley Hill,
Little River In Transylvania County, Penrose, Connestee, Crab Creek
and Cedar Mountain.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3533 8250 3519 8242 3516 8253 3516 8255
      3515 8257 3514 8261 3513 8263 3513 8264
      3512 8266 3513 8268 3510 8270 3509 8273
      3508 8274 3524 8276
TIME...MOT...LOC 1900Z 246DEG 3KT 3520 8262

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
304 PM EDT WED JUL 12 2017

NCZ063-064-121930-
Transylvania NC-Southern Jackson NC-
304 PM EDT WED JUL 12 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN TRANSYLVANIA AND
SOUTHEASTERN JACKSON COUNTIES UNTIL 330 PM EDT...

At 303 PM EDT, Doppler radar was tracking a strong thunderstorm 18
miles southwest of Brevard, or near Gorges State Park. This storm
was nearly stationary. Other storms are expected to develop across
the region this afternoon.

Locations to be impacted include... Rosman,
Cashiers, Lake Toxaway, Gorges State Park, Sapphire, Wolf Mountain,
Balsam Grove, Sassafras Mountain and Connestee.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3521 8304 3524 8276 3508 8274 3508 8275
      3507 8278 3508 8278 3509 8279 3501 8308
      3513 8313
TIME...MOT...LOC 1903Z 246DEG 3KT 3507 8299

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
310 PM EDT WED JUL 12 2017

NCZ064-065-121945-
Transylvania NC-Henderson NC-
310 PM EDT WED JUL 12 2017

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN TRANSYLVANIA AND
NORTHWESTERN HENDERSON COUNTIES UNTIL 345 PM EDT...

At 310 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Hendersonville, or near Etowah. This storm was nearly
stationary.

Locations to be impacted include...
Mills River, Etowah, Mountain Home, Asheville Airport, Fletcher,
Forge Mountain, Horse Shoe, North Transylvania and Penrose.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3544 8254 3543 8255 3542 8254 3543 8253
      3535 8245 3527 8266 3538 8272 3544 8262
      3544 8261 3543 8257 3544 8256
TIME...MOT...LOC 1910Z 246DEG 3KT 3535 8262

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
321 PM EDT WED JUL 12 2017

NCZ049-050-505-121945-
McDowell Mountains NC-Yancey NC-Mitchell NC-
321 PM EDT WED JUL 12 2017

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL MCDOWELL...SOUTHEASTERN
MITCHELL AND SOUTHEASTERN YANCEY COUNTIES UNTIL 345 PM EDT...

At 319 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles southwest of Spruce Pine. This storm was nearly stationary.
Other storms were developing near Little Switzerland and over
northern McDowell County.

Locations to be impacted include...
Spruce Pine, B.R. Parkway-Little Switzerland To Linville, Mount
Mitchell State Park, B.R. Parkway-Craggy To Little Switzerland, North
Cove, Busick, Celo, Ashford, Little Switzerland and Woodlawn.

Wind gusts up to 40 mph, pea size hail and very heavy rainfall rates
up to 2 inches per hour will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm may intensify, so be certain to monitor local radio and tv
stations, as well as local cable tv outlets for additional
information and possible warnings from the National Weather Service.

&&

LAT...LON 3593 8202 3591 8198 3592 8197 3589 8192
      3585 8193 3581 8199 3576 8195 3571 8203
      3570 8204 3566 8226 3586 8229 3596 8205
TIME...MOT...LOC 1919Z 246DEG 3KT 3584 8213

MOORE