Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
150 PM EDT Tue Jun 26 2018

.SYNOPSIS...
More seasonable temperatures are expected today with a stalled
cold front in the area. Scattered showers and thunderstorms will
develop. A passing trough makes showers and storms even more likely
Wednesday into Thursday, with hot weather returning to end the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 10:45am EDT Tuesday:  Another wet day with chances for severe
on tap, with the main threat window afternoon to evening.  Current
radar only shows a few light showers of the mountains, with more
general storms beginning in the mountains after 1pm and spreading
southwestward.  Wedge airmass is not very wedge-like, and skies are
scattered with afternoon temperatures expected to warm to just above
seasonal normal, and generate 1000 j/kg or so of SBCAPE.  Wind shear
has weakened some, leading to some reduction in storm severity, but
tree falls from storm outflows are still a likely result.

A surface boundary sits across the Carolinas at the south edge of
high pressure over the Northeast. This airmass more or less is
forming a wedge. The wedgelike pattern is expected to be somewhat
transient as the parent high quickly moves offshore, as the axis of
a narrow upper ridge moves onto the Eastern Seaboard by the end of
the day. The low level flow veers in response and thus low cloud
cover has been sparse overnight. Without the clouds, sunshine may
lead to the erosion of the wedge; it is unclear how well the models
have taken this into account. KGSP VAD suggests the winds have
already veered enough that the main forcing in play right now is
upslope over the mountains. This will drive some light showers there
this morning.

Despite the weakness of the wedge, max temps do look to be cooler
than they have been lately, perhaps 2-3 degrees over the Upstate
and several degrees further north (Charlotte may even remain
below normal today). This won't be enough to maintain stability,
however. Lapse rates remain pretty good aloft, and SBCAPE should
exceed 1000 J/kg over the whole CWFA, possibly much higher in
the southern zones. Unlike yesterday, we won't have the added
forcing and shear associated with a potent shortwave, though the
NAM suggests some convectively generated eddies may work into the
mountains this afternoon. So while initiation may not occur on such
a large scale, a few clusters of storms producing brisk outflows
are likely, and much of the area again receives likely PoPs. NAM
sfc-midlevel delta-theta-e values are sufficiently large for a
damaging downburst threat, and DCAPE plots from the SREF indicate
favorable 1000+ J values in the south. The Marginal Risk issued
by SPC for Day 1 looks appropriate.

The next trough moves thru the Ohio Valley tonight. Though the wedge
boundary may have retreated north by then, southerly flow still
develops over our area overnight ahead of the trough, and the NAM
and GFS both depict the boundary oozing south again. With abundant
moisture lingering in light of this, a small PoP is retained. The
trough will be close enough to the mountains at daybreak Wed
that chances begin to increase there after midnight. Mins will be
similar to those this morning.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM EDT Tuesday: Residual cool pool will still be in place
at the surface, but with the surface high well off into the Atlantic
at the start of the period. Upper trough pushing across the Great
Lakes will bring a front to our doorstep at the start of the period,
and with the cool pool scouring out ahead of the front, instability
should increase across the area with widespread convection expected
across most of the area (high chance for extreme southern/southeast
zones). Severe potential looks limited due to lack of deep-layer
shear, but SPC Day2 Marginal across the mountains certainly looks
warranted due to the proximity of the front and upper dynamics, with
wet microbursts the main concern. Highs will be pretty close to
seasonal normals, with low-level southwesterly flow and WAA
tempered by widespread cloud cover and convection.

The upper trough will pass by to the north as the front pushes into
the Piedmont by Thursday morning, stalling through the day but then
finally drifting a little more to the south late in the period.
However, despite the "front" (really just a wind shift) moving to
the south, temperatures will increase on Thursday by a good 3-5
degrees, with increasing thicknesses from the broad upper ridge
building over the MS Valley combined with a bit of a downsloping
component at least immediately adjacent to the Blue Ridge from the
wind shift. Luckily afternoon mixing and a bit of improvement to
dewpoints from the weak front will help to minimize heat index
concerns, and so yesterday afternoon's removal of heat wording in
the HWO still looks good. Convection will be significantly reduced
on Thursday due to the slightly drier airmass, but still a good
chance across the mountains and southern zones, with a minimum
across the NW NC Piedmont.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 315 AM EDT Tuesday: Upper ridge over the MS Valley to start
the period will slowly push east with the progressive wavetrain,
dominating the Southeast on Friday and lifting a little farther
northeast over the central Appalachians Saturday. Humidity will
return to the area Friday with some locations flirting with 105
across extreme southern zones and the Upper Savannah Valley, and
will continue heat wording in the HWO Friday and Saturday. Fairly
typical diurnal pops expected, though could see a bit of an increase
in pops creeping into southern zones as low-level flow begins to
shift out of the southeast, bringing a little more Atlantic moisture
into SC. On Saturday, said moist flow will continue to increase,
with a little more of an orographic upglide component as the high
shifts to the north. As we move toward the beginning of next week, a
bit of a weakness aloft will develop between the upper ridge exiting
to the northeast and a secondary one developing over the Desert
Southwest/Southern Plains. Slightly higher-than-diurnal pops
expected with no real relief from the heat, though not enough
confidence in heat indices to introduce any additional wording to
the HWO at this time.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Another round of thunderstorms this afternoon
and evening, with activity already beginning over the mountains, and
expected to spread over all areas over the next few hours.  Hi-res
model ensembles have showers mostly ending from the northwest to
southeast by 03Z.  This round of convection, and a similar round
Wednesday afternoon, is being assisted by the passage of an upper
wave across the north central CONUS which provides upper support.
Impact of wedge front has been minimal, as airmass has warmed to
produce typical amounts of instability for summertime afternoon
convection. Surface low associated with upper system has allowed
surface winds to become light southerly to southwesterly, against
the flow direction of wedge high pressure.  This has moved the
frontal zone northeastward, with mostly light and variable winds in
all areas.  Some northeasterly flow is expected to reassert itself
overnight with some return of wedge-like conditions with low
overcast Wednesday morning.

Outlook: A passing trough will enhance coverage of SHRA/TSRA again
Wednesday. Then another cold front will arrive from the northwest
on Thursday, although as a ridge builds over the East, hotter
but drier weather will return to end the week.  Patchy morning
fog and/or low stratus will continue to be an issue in mountain
valleys and/or locations with wet ground.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High  84%     Med   77%     Med   78%
KGSP       High 100%     High  86%     Low   48%     High  85%
KAVL       High 100%     Med   70%     Med   71%     High  91%
KHKY       High  94%     Med   73%     Med   74%     High  82%
KGMU       High 100%     High  86%     Med   63%     High  91%
KAND       High 100%     High  80%     Low   59%     High  84%

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...Wimberley
NEAR TERM...Wimberley/WJM
SHORT TERM...TDP
LONG TERM...TDP
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
521 AM EDT Tue Jun 26 2018

GAZ010-017-NCZ033-035>037-048>053-056>059-062>065-068-069-501>510-
270930-
Rabun-Habersham-Avery-Alexander-Iredell-Davie-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Catawba-Rowan-Graham-
Northern Jackson-Macon-Southern Jackson-Transylvania-Henderson-
Cleveland-Lincoln-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Greater Rutherford-Polk Mountains-Eastern Polk-
521 AM EDT Tue Jun 26 2018

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

.DAY ONE...Today and Tonight.

Scattered to numerous thunderstorms are expected to develop this
afternoon and evening. Some of these storms may become severe with
damaging winds as the main threat, but large hail cannot be ruled
out. Frequent cloud-to-ground lightning and brief heavy rain can be
expected as well.

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

..Wednesday...No hazardous weather is expected at this time.
..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.

.SPOTTER INFORMATION STATEMENT...

Skywarn spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

GAZ018-026-028-029-NCZ070>072-082-SCZ001>014-019-270930-
Stephens-Franklin-Hart-Elbert-Gaston-Mecklenburg-Cabarrus-Union-
Oconee Mountains-Pickens Mountains-Greenville Mountains-
Greater Oconee-Greater Pickens-Greater Greenville-Spartanburg-
Cherokee-York-Anderson-Abbeville-Laurens-Chester-Greenwood-
521 AM EDT Tue Jun 26 2018

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

.DAY ONE...Today and Tonight.

Scattered to numerous thunderstorms are expected to develop this
afternoon and evening. Some of these storms may become severe with
damaging winds as the main threat, but large hail cannot be ruled
out. Frequent cloud-to-ground lightning and brief heavy rain can be
expected as well.

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

..Wednesday...No hazardous weather is expected at this time.
..Thursday...Excessive heat possible.
..Friday...Excessive heat 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.

.SPOTTER INFORMATION STATEMENT...

Skywarn spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
128 PM EDT TUE JUN 26 2018

NCZ033-501>504-261800-
Caldwell Mountains NC-Burke Mountains NC-Greater Burke NC-
Greater Caldwell NC-Avery NC-
128 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT WEST CENTRAL CALDWELL...
SOUTHEASTERN AVERY AND NORTHWESTERN BURKE COUNTIES UNTIL 200 PM
EDT...

At 127 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles southeast of Newland, or 5 miles south of B.R. Parkway-Linville
Falls To Grandfather, moving southeast at 10 mph.

Locations to be impacted include...
Linville Falls, B.R. Parkway-Linville Falls To Grandfather, Table
Rock, Edgemont, Pineola, Collettsville, Jonas Ridge and Linville.

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 3597 8157 3580 8174 3597 8196 3605 8189
TIME...MOT...LOC 1727Z 304DEG 10KT 3597 8185

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
141 PM EDT TUE JUN 26 2018

NCZ064-065-261815-
Transylvania NC-Henderson NC-
141 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN TRANSYLVANIA AND
WESTERN HENDERSON COUNTIES UNTIL 215 PM EDT...

At 141 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles west of Hendersonville, or near Etowah, moving east at 10 mph.

Locations to be impacted include...
Hendersonville, Brevard, Mills River, Etowah, Mountain Home, Laurel
Park, Asheville Airport, Fletcher, Dupont State Forest and Looking
Glass.

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 8262 3544 8261 3543 8258 3544 8257
      3543 8254 3542 8254 3543 8253 3541 8243
      3520 8257 3527 8274 3532 8277 3541 8272
      3545 8264
TIME...MOT...LOC 1741Z 289DEG 8KT 3536 8262

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
153 PM EDT TUE JUN 26 2018

NCZ052-053-261830-
Buncombe NC-Haywood NC-
153 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL HAYWOOD AND
SOUTHWESTERN BUNCOMBE COUNTIES UNTIL 230 PM EDT...

At 152 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles northeast of Waynesville, or near Clyde, moving southeast at 5
mph.

Locations to be impacted include...
Waynesville, Canton, Lake Junaluska, Clyde and Cruso.

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 3549 8300 3562 8292 3560 8270 3540 8282
TIME...MOT...LOC 1752Z 293DEG 6KT 3555 8291

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
215 PM EDT TUE JUN 26 2018

NCZ505-506-261845-
McDowell Mountains NC-Eastern McDowell NC-
215 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN MCDOWELL COUNTY UNTIL
245 PM EDT...

At 214 PM EDT, Doppler radar was tracking a strong thunderstorm near
Marion, moving southeast at 5 mph.

Locations to be impacted include...
Marion, Sugar Hill, Pleasant Gardens, Nebo and Glenwood.

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 3569 8220 3575 8208 3569 8187 3556 8207
TIME...MOT...LOC 1814Z 308DEG 6KT 3569 8207

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
219 PM EDT TUE JUN 26 2018

NCZ064-SCZ002-003-261845-
Transylvania NC-Pickens Mountains SC-Greenville Mountains SC-
219 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN TRANSYLVANIA...
NORTHWESTERN GREENVILLE AND NORTHWESTERN PICKENS COUNTIES UNTIL 245
PM EDT...

At 219 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles south of Brevard, or 4 miles northwest of Table Rock State
Park, moving southeast at 5 mph.

Locations to be impacted include...
Rosman, Jones Gap State Park, Dupont State Forest, Caesars Head State
Park, Table Rock State Park, Jocassee Gorges, Gorges State Park,
Penrose, Connestee and Rocky Bottom.

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 3520 8274 3532 8263 3528 8261 3526 8262
      3526 8260 3521 8260 3517 8259 3515 8259
      3514 8257 3510 8256 3496 8289 3514 8289
TIME...MOT...LOC 1819Z 308DEG 6KT 3510 8274

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
221 PM EDT TUE JUN 26 2018

SCZ001-002-261845-
Pickens Mountains SC-Oconee Mountains SC-
221 PM EDT TUE JUN 26 2018

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN PICKENS AND
NORTHEASTERN OCONEE COUNTIES UNTIL 245 PM EDT...

At 221 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles north of Walhalla, or near Devils Fork State Park, moving
southeast at 5 mph.

Locations to be impacted include...
Salem, Devils Fork State Park, Keowee Toxaway State Park, Oconee
State Park, Lake Jocassee, Lake Keowee, Jocassee Gorges, Mountain
Rest and Bad Creek.

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.

Lake Jocassee and Lake Keowee are in the path of this storm. Cloud
to ground lightning and gusty winds will create dangerous boating
conditions.
Move to shore immediately.

&&

LAT...LON 3492 8317 3492 8316 3493 8315 3493 8314
      3494 8313 3494 8311 3495 8313 3496 8311
      3502 8305 3506 8289 3489 8288 3479 8301
      3481 8317 3489 8320
TIME...MOT...LOC 1821Z 308DEG 6KT 3494 8299

MOORE