Severe Thunderstorm Warning 99, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
305 PM EDT Wed May 31 2017

.SYNOPSIS...
A weak cold front slowly moves through the area early Thursday.
Dry high pressure will follow the front for late Thursday and
Friday, but as high pressure slides offshore, moist southerly flow
returns and shower and thunderstorm chances increase heading into
the weekend. Temperatures will remain near normal until another
cold front moves through the region early next week with drier
and cooler conditions to follow.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 235 PM EDT: a few widely sct cells have begun to develop across
the CWFA over the past hour or so with one cell producing a few cloud
to ground lightning strikes. The latest CAM guidance has not changed
much since earlier today with additional convection expected to fire
off the escarpment and higher terrain over the next few hours and drift
eastward. Coverage still looks hit or miss for most locations, but the
region along the escarpment will likely have the best coverage overall.
Convection should die down after 00z or so, with instability waning.
Otherwise, the axis of the broad upper trough will continue to shift
east across the Ohio Valley, as steep upper ridging persists over the
Rockies. The deeper moisture will shift SE later this evening as broad
sfc high pressure begins to spread over the fcst area. This trend will
continue thru tomorrow with winds becoming NWLY by late morning and
remaining WLY TO NWLY thru the evening. Convection potential looks
lower tomorrow than the past couple of days with minimal instability
across the CWFA, but some isolated to sct coverage is possible. The
severe threat looks very low. Overnight low temps should be near normal
with some patchy fog likely to develop. High temps tomorrow will be
similar to today, if not a degree or 2 higher.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 240 PM Wednesday: The end of the week looks fairly uneventful
as we remain in an overall W/NW flow aloft with a lack of mid/upper
forcing and a relatively dry air mass, which should be generally
unfavorable to diurnal convection. The trend in the new guidance
is for less in the way of convection each day and the new forecast
follows that trend. The model guidance is especially uninterested
in convective development on Friday, so we have cut back to only a
slight chance over the higher terrain of the central and southern
mountains of NC that ends around sunset. Saturday afternoon holds
a better opportunity for convection, but nothing more than climo
at best if the model trend is correct, so we have cut back to a
chance over the higher terrain and a slight chance outside the
mtns. Some of the convection could linger into the evening east of
the Blue Ridge, but should end by midnight. Little indication of
any MCS activity, so the fcst will be dry for the pre-dawn hours
on Sunday. Temps will be seasonally warm with a warming trend from
Friday into Saturday.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A shortwave moves across the Great Lakes Sunday afternoon with
an attendant weak trough axis moving across the region that may
help to increase shower and thunderstorm coverage given moist
southerly low-level flow on the back side of a subtropical ridge.
However, instability parameters are rather anemic, with weak
deep-layer shear, a deep boundary layer, and moist mid-levels
(poor lapse-rates) leading to unimpressive CAPE.  This appears
to be a change from previous guidance which had more robust
shear parameters.  Given previous guidance and potential modest
shortwave forcing in a moist environment, we will have to continue
to monitor the potential for storms but scattered coverage of
showers is still expected at this time.

On Monday, the guidance is in better agreement about a positively
tilted closed upper-level low dropping south over the Great Lakes
while we remain in a moist, southwesterly flow.  The presence of
this deeper trough in advance of an attendant cold front to our
west should increase shear and lower our LCLs, thereby increasing
CAPE across the area and increasing the potential for some stronger
storms.  Nevertheless, heading into Tuesday, while guidance is in
disagreement regarding the progressiveness of the upper-level low,
precip chances wane as the cold front moves through.

It appears the operational guidance (GFS/Canadian/ECMWF) has slowed
the frontal passage from the evening runs.  There is plenty of time
to nail down the details, but the current forecast is essentially
a blend of the guidance and is closest to the 12 UTC GFS with a
Tuesday afternoon passage.

In advance of the front, high temperatures will remain near-normal
with low-temperatures up to 5 degrees above normal with high
humidity and cloud cover. Below-normal high and low temperatures
are in store by Tuesday as the front moves through the region and
the dry continental airmass brings an unusual reprieve from what
should be early summer heat and humidity.  High temperatures may be
hard-pressed to reach 80 in the Piedmont under mostly sunny skies
next Wednesday, with dewpoints in the mid 50s.  If this comes to
pass, this childhood Yankee will be the first to celebrate.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: expect VFR conditions thru TAF period with
a TEMPO from 20 to 23z for reduced visby and gusty winds from TSRA
at KCLT. Confidence is not very high that convection will affect the
site, but it is high enough to include the TEMPO. Otherwise, sct mid
and high clouds will continue to stream over roughly the southeastern
half of the CWFA area thru the afternoon with isolated to scattered
SHRA and TSRA likely to develop across the Blue Ridge and drift east
into the Piedmont. Conditions should clear out later this evening,
with patchy fog possible where precip occurs. Drier conditions are
expected tomorrow under broad high pressure, and winds should veer
around to NWLY by the late morning.

Outlook: we get back into a warm-season pattern on Friday that will
allow a return of afternoon SHRA/TSRA through the weekend.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
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 100%     High 100%
KAND       High 100%     High 100%     High 100%     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...JMP
NEAR TERM...JPT
SHORT TERM...PM
LONG TERM...JMP
AVIATION...JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
410 AM EDT Wed May 31 2017

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-010815-
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-
410 AM EDT Wed May 31 2017

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

.DAY ONE...Today and Tonight.

Scattered showers and thunderstorms will continue into the evening.
Strong gusty winds, brief heavy rainfall, and frequent cloud to
ground lightning could occur with any of the storms.

.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.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
335 PM EDT WED MAY 31 2017

NCZ068-312000-
Cleveland NC-
335 PM EDT WED MAY 31 2017

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL CLEVELAND COUNTY UNTIL
400 PM EDT...

At 335 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles east of Forest City, or near Ellenboro, moving east at 15 mph.

Locations to be impacted include...
Shelby, Boiling Springs NC, Belwood, Lawndale, Patterson Springs,
Fallston, Polkville, Lattimore, Mooresboro and Earl.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3550 8150 3517 8147 3523 8176 3535 8170
      3545 8170
TIME...MOT...LOC 1935Z 264DEG 14KT 3534 8174

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
340 PM EDT WED MAY 31 2017

NCZ056-069-312015-
Lincoln NC-Catawba NC-
340 PM EDT WED MAY 31 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN CATAWBA AND EASTERN
LINCOLN COUNTIES UNTIL 415 PM EDT...

At 340 PM EDT, Doppler radar was tracking a strong thunderstorm 6
miles south of Newton, or near Maiden, moving east at 20 mph.

Locations to be impacted include...
Newton, Lincolnton, Maiden, Westport, Boger City, Iron Station,
Denver, Lake Norman, Lowesville and Sherrills Ford.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3561 8094 3559 8093 3557 8096 3555 8096
      3553 8094 3553 8095 3550 8096 3549 8095
      3547 8095 3545 8094 3543 8096 3540 8096
      3540 8103 3549 8133 3567 8129 3565 8096
      3562 8092
TIME...MOT...LOC 1940Z 281DEG 19KT 3557 8122

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
345 PM EDT WED MAY 31 2017

SCZ002-003-005>007-312015-
Pickens Mountains SC-Greater Pickens SC-Greenville Mountains SC-
Spartanburg SC-Greater Greenville SC-
345 PM EDT WED MAY 31 2017

...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN GREENVILLE...
NORTHWESTERN SPARTANBURG AND PICKENS COUNTIES UNTIL 415 PM EDT...

At 345 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 8 miles south of Columbus to 10 miles west of
Pickens, and moving southeast at 10 mph.

Locations to be impacted include...
Pickens, Easley, Greer, Taylors, Berea, Boiling Springs SC, Travelers
Rest, Lyman, Slater-Marietta and Inman.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3477 8289 3479 8288 3482 8290 3490 8291
      3491 8290 3492 8291 3494 8290 3495 8291
      3496 8291 3497 8292 3498 8294 3518 8216
      3502 8186 3475 8288
TIME...MOT...LOC 1945Z 316DEG 7KT 3512 8219 3494 8288

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
412 PM EDT WED MAY 31 2017

NCZ069-070-312045-
Gaston NC-Lincoln NC-
412 PM EDT WED MAY 31 2017

...STRONG THUNDERSTORMS WILL IMPACT SOUTHEASTERN LINCOLN AND GASTON
COUNTIES UNTIL 445 PM EDT...

At 412 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 8 miles east of Lincolnton to 9 miles northeast
of Shelby, and moving southeast at 15 mph.

Locations to be impacted include...
Lincolnton, Gastonia, Mt Holly, Cherryville, Bessemer City, Dallas,
Stanley, Ranlo, High Shoals and Iron Station.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3535 8096 3535 8097 3531 8099 3524 8131
      3525 8132 3526 8132 3528 8136 3533 8136
      3536 8141 3542 8146 3550 8107 3547 8095
      3545 8094 3543 8096 3539 8095 3537 8099
      3536 8097 3538 8096 3536 8092
TIME...MOT...LOC 2012Z 294DEG 14KT 3547 8110 3539 8143

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
418 PM EDT WED MAY 31 2017

SCZ003-005>007-312100-
Greater Pickens SC-Greenville Mountains SC-Spartanburg SC-
Greater Greenville SC-
418 PM EDT WED MAY 31 2017

...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN GREENVILLE...
NORTHERN SPARTANBURG AND EAST CENTRAL PICKENS COUNTIES UNTIL 500 PM
EDT...

At 418 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 12 miles northwest of Spartanburg to 4 miles
north of Easley, and moving southeast at 10 mph.

Locations to be impacted include...
Greenville Downtown, Spartanburg, Easley, Pickens, Greenville
Eastside, West Greenville, Greer, Mauldin, Taylors and Berea.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3478 8245 3482 8248 3476 8262 3489 8274
      3496 8257 3514 8206 3502 8178 3496 8177
      3472 8246
TIME...MOT...LOC 2018Z 308DEG 11KT 3507 8208 3489 8261

TDP

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
432 PM EDT WED MAY 31 2017

NCZ037-057-312100-
Rowan NC-Davie NC-
432 PM EDT WED MAY 31 2017

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL DAVIE AND NORTH CENTRAL
ROWAN COUNTIES UNTIL 500 PM EDT...

At 432 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southeast of Mocksville, or near Cooleemee, moving east at 20
mph.

Locations to be impacted include...
Mocksville, Cooleemee, High Rock Lake, Fork Church, Advance and
Woodleaf.

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...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3575 8061 3593 8060 3595 8038 3589 8037
      3588 8042 3587 8039 3585 8039 3585 8042
      3583 8043 3583 8046 3584 8047 3583 8049
      3581 8047 3579 8048 3577 8045 3574 8045
      3573 8040 3572 8034 3571 8032
TIME...MOT...LOC 2032Z 273DEG 17KT 3584 8052

TDP