Severe Thunderstorm Warning 264, NWS Greenville-Spartanburg, SC

664 
WWUS52 KGSP 232006
SVSGSP

Severe Weather Statement
National Weather Service Greenville-Spartanburg SC
406 PM EDT WED AUG 23 2017

NCC119-179-SCC091-232015-
/O.CAN.KGSP.SV.W.0264.000000T0000Z-170823T2030Z/
Mecklenburg NC-Union NC-York SC-
406 PM EDT WED AUG 23 2017

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN MECKLENBURG...CENTRAL
UNION AND EAST CENTRAL YORK COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore the warning has been cancelled. However thunderstorms 
could strengthen again as they move southeast across the area.

LAT...LON 3491 8043 3495 8080 3508 8091 3503 8090
      3501 8091 3499 8089 3497 8088 3496 8087
      3497 8098 3515 8097 3518 8048 3516 8046
      3516 8044 3517 8042 3516 8041
TIME...MOT...LOC 2002Z 272DEG 23KT 3506 8071 

$$

RWH

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
211 PM EDT Wed Aug 23 2017

.SYNOPSIS...
A cold front will move through the region today, allowing for
increasing precipitation chances. High pressure building in behind
the front will introduce an extended period of unseasonably cool
conditions that is expected to last through at least early next
week. Although active tropical weather is anticipated near the
Southeast early next week, this is unlikely to have any impact on
the weather over our area for at least the next 7 days.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 210 PM EDT Wednesday: Closed upper low just southeast of James
Bay will continue to lift NE through the period, though the upper
trough axis will remain in place down the Appalachians. Surface low
and attendant cold front (which is right over our forecast area at
AFD time) will continue to slide toward the coast, pushing into the
ocean overnight. Along and ahead of the front, convection has
developed across the Piedmont. sbCAPEs are generally between 1000-
2000 J/kg, with best dCAPEs to our southeast ahead of the front.
Deep layer shear is minimal at best, though seeing some 25-30kt
effective bulk shear right along the front. SPC Marginal Risk
continues to just barely grab extreme eastern Union County NC, with
general thunder elsewhere. All this to say that gusty winds and of
course lightning/heavy rain certainly possible, and cannot totally
rule out a brief damaging wind gust through the afternoon hours.

Canadian high pressure moves in behind the front, ushering in a very
pleasant airmass change. Flow aloft as the trough axis passes the
spine of the Appalachians will shift to NW with a bit of an upslope
component, so cannot rule out some isolated showers across the
mountains tomorrow, and some guidance depicts some lingering showers
across the Piedmont, but the bigger story will be high temperatures
which will drop a handful of degrees below seasonal normals, with
dewpoints tomorrow afternoon a good 10 degrees lower than today,
setting up a nice trend as we move into the short term.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 130 PM Wednesday: Northern CONUS high pressure will remain
dominant over our area Thursday night and Friday, with an upper
trough axis along the Eastern Seaboard. Initially northerly flow
will begin to veer as the pattern progresses ever so slightly
heading into Saturday. Moderately cool and dry conditions
will accompany the high, keeping convective potential small in
conjunction with low-level subsidence. Maxes about a category below
normal are expected. Nonetheless model consensus indicates slight
destabilization over our southwestern mountains Friday afternoon,
so an isolated shower is not out of the question. The more easterly
fetch leads to slightly higher dewpoints and more widespread SBCAPE
Saturday, and a stronger model response for precip along the Blue
Ridge. Thus PoPs expand a bit then. Increased cloud cover however
appears likely to keep temps even cooler, about two categories
below normal.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 140 PM EDT Wednesday:  The medium range period kicks off on
Saturday evening amidst a rather active synoptic setup.  The pattern
will be highlighted by a departing longwave trof over the northeast,
while a pair of tropical systems dominate across the lower latitudes
of the CONUS.  The first and most distinct still looks to be what
is now TD Harvey, which by Saturday night is progged to be slowly
churning inland over eastern TX.  The second disturbance currently
has a low chance of becoming a TC as it sits over the FL Keys,
eastward toward the Bahamas.  Closer to home, a strong 1028MB
high pressure centered over Ontario/Quebec will be stretching
southward across the eastern CONUS along the east coast in lee of
the southern Appalachians.  With that, the fcst initializes with
decreasing diurnal pops along the high terrain, with further drying
expected on Sunday as the wedge builds across the region leading
to below climo pops outside of the mtns, near/above climo in.

Additional drying continues into Monday as an approaching upper
trof over the upper Midwest amplifies shortwave ridging along the
Appalachians, which will turn reinforce the wedge of high pressure.
In addition, guidance favors the south FL system referenced above
to move northeast offshore of the Carolina coastlines by Monday
morning.  Flow around said system will also work to enhance the
southern extent of the wedge and associated dry air.  By Tuesday
guidance tends to diverge a bit more with regards to timing of
both tropical systems and the approaching upper trof and associated
surface front.  The GFS is a bit slower with TC Harvey's northward
migration as it favors a deeper upper trof and a slow yet robust
surface front.  The ECMWF on the other hand has a less amplified
upper trof over the OH Valley by Tuesday night, with the front well
northward and possibly stalled thanks to a more northern position
of Harvey.  All in all, conditions look surprisingly dry Tuesday
through Wednesday as well across northeast GA and the western
Carolinas aside for possible mtn convection and stratiform upglide
precipitation along the periphery of the wedge front.  Therefore
pops will remain below climo levels Monday through Wednesday.
Temperatures will remain below climo as well given abundant sky
cover thanks to the persistence of the wedged airmass.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
At KCLT and Elsewhere: Cold front moving across the area has already
switched winds around to NW at CLT and other NC sites, with the SC
sites soon to follow. Scattered convection developing will spread SE
across the area, and have continued TEMPO TSRA for all sites but
KAVL (which at best should only see SHRA) for the next few hours.
Convection will clear behind the front overnight, with the
possibility of some mountain valley fog/low stratus as usual. W to
WNW winds to start the period (up-valley and occasionally gusty at
KAVL) will continue to swing around to NE by the end of the period.

Outlook: Drier air will move in behind the front on Thursday, with
only some isolated mountain showers expected in the afternoon. Low
level moisture may make a return toward the Blue Ridge over the
weekend.

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  97%     High  93%     High  90%
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...JDL
NEAR TERM...TDP
SHORT TERM...Wimberley
LONG TERM...CDG
AVIATION...TDP

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
626 AM EDT Wed Aug 23 2017

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-501-503-
505-507-509-SCZ001>006-010-011-019-241030-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-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-Oconee Mountains-Pickens Mountains-
Greenville Mountains-Greater Oconee-Greater Pickens-
Greater Greenville-Anderson-Abbeville-Greenwood-
626 AM EDT Wed Aug 23 2017

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

.DAY ONE...Today and Tonight.

Scattered thunderstorms are expected to develop across the area
today, primarily this afternoon. The main threats will be from
cloud to ground lightning and locally heavy rainfall.

.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.

NCZ035>037-056-057-068>072-082-502-504-506-508-510-SCZ007>009-
012>014-241030-
Alexander-Iredell-Davie-Catawba-Rowan-Cleveland-Lincoln-Gaston-
Mecklenburg-Cabarrus-Union-Greater Caldwell-Greater Burke-
Eastern McDowell-Greater Rutherford-Eastern Polk-Spartanburg-
Cherokee-York-Laurens-Chester-
626 AM EDT Wed Aug 23 2017

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

.DAY ONE...Today and Tonight.

Scattered thunderstorms are expected to develop across the Piedmont
and foothills today, primarily this afternoon into the evening. While
the main threats will be from cloud to ground lightning and locally
heavy rainfall, a few isolated severe storms will be possible, mainly
east of I-26 in South Carolina, and east of the Blue Ridge in North
Carolina. Brief damaging wind gusts will be the main threats with
any severe 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.

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
316 PM EDT WED AUG 23 2017

NCZ072-231945-
Cabarrus NC-
316 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
NORTHEASTERN CABARRUS COUNTY UNTIL 345 PM EDT...

At 316 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 10 miles east of Downtown Concord, or near Mt
Pleasant, moving east at 25 mph.

Locations to be impacted include...
Mt Pleasant.

In addition to intense lightning, wind gusts up to 50 mph 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.

Frequent lightning is occurring with this storm. If outdoors, try to
get indoors or into a hard topped vehicle. Otherwise, stay away from
open areas and isolated high objects such as trees. When indoors,
stay away from windows and doors and avoid using wired electronic
devices. Do not take a shower or bath. Try to unplug unnecessary
appliances before the storm approaches.

&&

LAT...LON 3529 8043 3528 8044 3528 8045 3548 8051
      3550 8038 3550 8030
TIME...MOT...LOC 1916Z 258DEG 21KT 3539 8041

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
339 PM EDT WED AUG 23 2017

NCZ071-082-SCZ009-232015-
Union NC-Mecklenburg NC-York SC-
339 PM EDT WED AUG 23 2017

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT SOUTHERN
MECKLENBURG...NORTHWESTERN UNION AND EAST CENTRAL YORK COUNTIES UNTIL
415 PM EDT...

At 339 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 10 miles northeast of Rock Hill, or near Pineville,
moving east at 25 mph.

Locations to be impacted include...
Monroe, South Charlotte, Southwest Charlotte, Matthews, Mint Hill,
Indian Trail, Weddington, Fort Mill, Stallings and Pineville.

In addition to intense lightning, wind gusts up to 50 mph 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.

Frequent lightning is occurring with this storm. If outdoors, try to
get indoors or into a hard topped vehicle. Otherwise, stay away from
open areas and isolated high objects such as trees. When indoors,
stay away from windows and doors and avoid using wired electronic
devices. Do not take a shower or bath. Try to unplug unnecessary
appliances before the storm approaches.

&&

LAT...LON 3495 8079 3508 8091 3503 8090 3501 8091
      3499 8089 3497 8088 3496 8087 3496 8098
      3514 8100 3520 8055 3493 8054
TIME...MOT...LOC 1939Z 267DEG 23KT 3506 8091

RWH