Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EDT Mon Jun 19 2017

.SYNOPSIS...
A cold front slowly moves across our area this evening enhancing
shower and thunderstorm coverage before stalling across the Midlands
on Tuesday.  The remnant frontal boundary may lift back north late
Tuesday for another round of showers and storms before dissipating
as drier high pressure builds in for Wednesday.  Rainfall chances
increase yet again late week as tropical moisture spreads across
the Southeast U.S.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 1030 PM EDT Monday: Another round of updates for convective
trends, which are diminishing across the Blue Ridge and adjacent
foothills but on the increase with concern for training convection
across portions of the Piedmont. All guidance points to this
activity really waning between 06-08z but until then heavy rain and
possible isolated flash flooding remain the primary threat. Also did
end up bumping overnight lows up just a tad across the Piedmont
while dropping them ever so slightly across the mountains, but
resulting zone-based forecasts probably won't really change much.

Otherwise, front and upper wave will gradual pass through the CWA,
exiting Tuesday morning.  Upper flow has improved some with the
presence of the large eastern CONUS upper wave, but with very veered
southwesterly surface flow, overall bulk shear is still weak at less
than 20kts. High PW levels ahead of front also suggest some
potential for flooding in areas receiving training storms.  With
improved upper flow, storm are moving eastward more rapidly than
recent storms, which will mitigate rain accumulation some, but focus
provide by front could lead to some training of storms across the
same area.

With front to provide focus, scattered showers and thunderstorms
will continue through tonight with some letup early Tuesday morning
as front exits the area and some dry advection begins to stabilize
the airmass.  However, more showers and thunderstorms are expected
Tuesday afternoon in piedmont areas, though at a less severe level,
as forcing from upper wave will continue, and some moisture remains
behind the front.

With cold FROPA and extensive cloud cover, highs Tuesday will be
significantly cooler than recent history, at around 80 degrees in
the piedmont.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 300 PM EDT Monday: The front will be stalled near the area for
the middle of the week as tropical moisture flows northward from the
Gulf of Mexico. Models disagree on the exact location of the
boundary but it does look like most of the area will have rain
chances each period. Right now it looks as though the Piedmont and
blue ridge have the highest chance of rain with the lowest chance
along the Tennessee border. We will have to watch for localized
heavy rainfall with this pattern since the precipitable water values
will be in the 1.5 to 2 inch range.

Due to the increased moisture and cloud cover through the period,
high temperatures both Tuesday and Wednesday will only be in the
lower 80s in the Piedmont with some higher peak remaining in the
60s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
At the beginning of the period, operational model consensus
(ECMWF, GFS, Canadian) place a relatively weak tropical low on
either side of the Sabine River Valley along the TX/LA border.
The associated closed upper-low is to the south of fairly zonal flow
across the CONUS and caught between the weakness of two deep-layer
ridges to its west and east.  Therefore, the overall pattern
places our region within deep southerly to southwesterly flow on
the northwest side of the Atlantic subtropical ridge and to the
east of the tropical low .  This flow will be tropical in origin
with a fetch potentially originating from the western Caribbean
Sea which means the potential is there for very efficient/heavy
rainfall from late Thursday night through Saturday, before the
Atlantic ridge builds west across Florida and the east-west ridge
axis obstructs the tropical moisture fetch.  Guidance has PWs above
2-2.25 inches which would be near record-level values for the region
during this time.  Additionally, pieces of shortwave energy aloft
will eject from the upper-low over the Lower MS River Valley and
propagate across the TN Valley and into the southern Appalachians
Friday as the closed-low weakens and gradually becomes absorbed
into the westerlies late Friday into Saturday, moving across the
area as a shortwave trough late Saturday into early Sunday. While
the pieces are there for periods of heavy rainfall and at least
localized flash flooding, especially as this tropical flow is
forced up the southern Appalachians, guidance isn't particularly
bullish on widespread heavy rain as the main tropical energy stays
too far west and weakens substantially as the remnants advect east.
We'll keep a close eye on the evolution of any tropical activity,
and some heavy rainfall is likely, but there's no need to get overly
concerned at this time.  Therefore, the forecast maintains likely
pops over the mountains through Saturday afternoon, and high-end
chance elsewhere.  High temperatures should be near normal if not
slightly below with dewpoints east of the mountains uncomfortably
in the low-70s keeping low temperatures a few degrees above normal.

Unfortunately, the shortwave trough and remnant tropical moisture is
quickly followed by an approaching cold front and deeper upper-level
trough.  Details on the timing of the frontal passage will have to
be worked out over the next several days but the current forecast is
a blend of the EC and GFS with FroPa overnight Sunday/early Monday.
Quieter, and more importantly, drier weather may follow the front
beyond the period by mid-week next week.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Only change for the KCLT TAF for the 03z AMD
is to add gusty winds to the TEMPO TSRA. Storm approaching the area
from Upstate SC has some 40kt inbounds from KCLT, so assuming it
holds together, need to add this to the TAF. Probably won't need the
TEMPO through 05z as so far no additional convection is developing
behind this but will leave it in for now. Otherwise, slow clearing
trend this evening as the front passes overnight, and while there
remains some chance of daybreak fog/low cigs, chances not high
enough to include at this time. As the front pushes through, SW
winds will veer NW and eventually around the compass to NE/E/SE
through the day tomorrow. Front looks to stall across the area
Tuesday afternoon, and while KAVL/KHKY should be VFR and precip-
free, other sites not so lucky with all guidance redeveloping a
surge of MVFR to IFR cigs lifting to the N during the afternoon.
PROB30 TSRA warranted for Upstate TAFs and KCLT.

Outlook: Cold front will stall over the area on Tuesday, maintaining
scattered convection and associated periodic restrictions through
the end of the week, with a return of morning fog/low stratus. Drier
conditions may finally return during the latter part of the week if
the cold front can push south of the area, however confidence
remains low as possible remnants of a tropical system may impact
the area late in the week.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High  97%     High 100%     High 100%     High  82%
KGSP       High 100%     High 100%     High 100%     High  83%
KAVL       High  98%     High  95%     High 100%     Med   78%
KHKY       High 100%     High 100%     High 100%     Med   79%
KGMU       High 100%     High 100%     High 100%     High  83%
KAND       High 100%     Med   75%     Med   78%     High  83%

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...TDP/WJM
SHORT TERM...SW
LONG TERM...JMP
AVIATION...TDP

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
853 PM EDT Mon Jun 19 2017

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-210100-
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-
853 PM EDT Mon Jun 19 2017

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

.DAY ONE...Tonight.

A cold front will continue to slowly cross the area and into the
Piedmont tonight. Scattered thunderstorms will continue this
evening. Very heavy rainfall will be possible and isolated flash
flooding may develop in areas repeatedly affected by thunderstorms.
Some thunderstorms may be strong with small hail and brief gusty
winds, especially across the North Carolina Piedmont.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

..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.
..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.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
946 PM EDT MON JUN 19 2017

NCZ068-SCZ007>009-013-200230-
Cleveland NC-York SC-Cherokee SC-Union SC-Spartanburg SC-
946 PM EDT MON JUN 19 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN CLEVELAND...WESTERN
YORK...SOUTHEASTERN SPARTANBURG...CHEROKEE AND NORTHERN UNION
COUNTIES UNTIL 1030 PM EDT...

At 945 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles southeast of Spartanburg, or near Pacolet, moving northeast at
40 mph.

Locations to be impacted include...
Gaffney, York, Spartanburg, Pacolet, Blacksburg, Roebuck, Jonesville,
Pacolet Mills, Grover and Sharon.

Wind gusts up to 40 mph and small hail will be possible over 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 3468 8184 3491 8199 3524 8137 3518 8132
      3516 8133 3516 8131 3496 8114
TIME...MOT...LOC 0145Z 240DEG 35KT 3486 8177

JPT

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
950 PM EDT MON JUN 19 2017

NCZ082-200230-
Union NC-
950 PM EDT MON JUN 19 2017

...A STRONG THUNDERSTORM WILL IMPACT UNION COUNTY UNTIL 1030 PM
EDT...

At 949 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles southwest of Monroe, or 4 miles south of Mineral Springs,
moving northeast at 30 mph.

Locations to be impacted include...
Monroe, Unionville, Wesley Chapel, Wingate, Waxhaw, Marshville, Lake
Park, Mineral Springs, Fairview In Union County and Sturdivants.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3485 8032 3481 8043 3482 8080 3494 8078
      3496 8080 3519 8051 3516 8044 3517 8042
      3517 8039 3518 8037 3517 8036 3519 8028
TIME...MOT...LOC 0149Z 237DEG 24KT 3487 8067

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1026 PM EDT MON JUN 19 2017

NCZ068-070-SCZ008-009-200315-
Gaston NC-Cleveland NC-York SC-Cherokee SC-
1026 PM EDT MON JUN 19 2017

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN CLEVELAND...
SOUTHWESTERN GASTON...NORTHWESTERN YORK AND NORTHEASTERN CHEROKEE
COUNTIES UNTIL 1115 PM EDT...

At 1026 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles east of Gaffney, or near Smyrna, moving northeast at 30 mph.

Locations to be impacted include...
Gastonia, Kings Mountain, Bessemer City, South Gastonia, Clover,
Dallas, Blacksburg, Grover, Hickory Grove and Smyrna.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3515 8102 3515 8104 3513 8105 3512 8104
      3495 8147 3510 8158 3536 8121 3516 8101
TIME...MOT...LOC 0226Z 240DEG 25KT 3507 8144

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1031 PM EDT MON JUN 19 2017

NCZ082-200315-
Union NC-
1031 PM EDT MON JUN 19 2017

...A STRONG THUNDERSTORM WILL IMPACT UNION COUNTY UNTIL 1115 PM
EDT...

At 1031 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles southwest of Monroe, or near Mineral Springs, moving northeast
at 30 mph.

Locations to be impacted include...
Monroe, Wingate, Waxhaw, Marshville, Mineral Springs, Sturdivants,
Wesley Chapel, Unionville, Jaars and Trinity.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3481 8032 3482 8080 3494 8078 3495 8080
      3517 8028
TIME...MOT...LOC 0231Z 240DEG 24KT 3489 8069

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1037 PM EDT MON JUN 19 2017

GAZ029-SCZ011-200315-
Elbert GA-Abbeville SC-
1037 PM EDT MON JUN 19 2017

...STRONG THUNDERSTORMS WILL IMPACT SOUTHEASTERN ELBERT AND
SOUTHEASTERN ABBEVILLE COUNTIES UNTIL 1115 PM EDT...

At 1036 PM EDT, Doppler radar was tracking a strong thunderstorms 14
miles southeast of Elberton, or near Lake Strom Thurmond, moving
northeast at 20 mph.

Locations to be impacted include...
Abbeville, Calhoun Falls, Nancy Hart State Park, Bobby Brown State
Park, Lake Strom Thurmond, Lake Russell, Fortsonia, Rice Town and
Promised Land.

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...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3398 8261 3397 8264 3399 8265 3397 8278
      3399 8283 3398 8286 3401 8291 3422 8226
      3415 8224 3411 8226 3406 8234 3406 8244
      3408 8248 3407 8253 3401 8260 3396 8257
TIME...MOT...LOC 0236Z 240DEG 24KT 3402 8264

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1122 PM EDT MON JUN 19 2017

NCZ071-072-200345-
Cabarrus NC-Mecklenburg NC-
1122 PM EDT MON JUN 19 2017

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN CABARRUS AND NORTH
CENTRAL MECKLENBURG COUNTIES UNTIL 1145 PM EDT...

At 1122 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles south of Huntersville, or 4 miles west of Northeast Charlotte,
moving northeast at 30 mph.

Locations to be impacted include...
Huntersville, Downtown Concord, Kannapolis, Northeast Charlotte, West
Concord, Coddle Creek Reservoir, Charlotte Motor Speedway, UNC
Charlotte, Harrisburg and Northwest Charlotte.

Wind gusts up to 40 mph will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The combination of gusty winds and saturated soil conditions will
cause scattered trees and power lines to fall. Seek shelter inside an
interior room.

&&

LAT...LON 3536 8056 3528 8086 3536 8093 3551 8076
      3551 8071
TIME...MOT...LOC 0322Z 236DEG 26KT 3534 8087

KRENTZ