Severe Thunderstorm Warning 257, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
434 PM EDT Fri Jul 28 2017

.SYNOPSIS...
A strong cold front will cross the region from the west through
tonight. Cooler and drier air will arrive across the western
Carolinas and northeast Georgia through the weekend and linger
through the early part of next week. More typical summertime
conditions will return about the middle of next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 430 PM: Loosely organized tstms are oriented just west of I-77
attm. Per SPC Mesoanalysis SBCAPE in this area is near 3000 J/kg,
and given DCAPE exceeding 1000 J it is no surprise that strong
gust fronts characterized by 30-40 kt peak gusts being present
all along the line. Numerous wind damage reports have come in
from the Upstate indicating pockets of stronger downdrafts; hence
liberal use of SVRs. Height falls/tightening height gradient is
expected to result in improving shear throughout the afternoon,
with 0-3km values likely reaching 20-25 kts by late afternoon. This
will be adequate to support continued clustering along cold pools,
supporting a risk of localized damaging winds, especially across
the Piedmont.

A lull in convection of at least a couple of hours appears
to be in the offing once the existing lines exit the area by
about 600 PM. However, we will have to monitor convective trend
across the TN Valley (ahead of the cold front) this afternoon,
as any activity developing that way could find its way into our
far western areas this evening. So far, the air mass across East
Tennessee is struggling to recover from the morning showers that
moved across that area. However, numerous, albeit not especially
strong showers and storms are developing at the leading edge of
an axis of 2000+ sbCAPE across west/middle Tennessee. The more
robust shear remains across the Ohio Valley, and given the rather
modest levels of instability, especially east of the Cumberland
Plateau. While some of those West-Middle TN storms are weakly
organizing much as our local activity has, it looks unlikely
they will grow upscape into a truly organized MCS. Nevertheless,
we will feature likely pops across the mtns this evening, tapering
to chances east of the Blue Ridge for scattered to numerous showers
and a few storms moving into our western areas this evening.

With low level moisture remaining abundant, and mid/upper level
clearing, fog formation is possible late tonight, especially
in sheltered areas, where it could become locally dense. Deeper
moisture and wind shift associated with cold front is expected
to ooze to our southern areas, or just to our south by sunrise
Saturday. Token small pops will be maintained in these areas through
the day, as well as across the mtns (for a relatively moist NW
flow), and across the eastern zones (due to upper level thermal
trough developing in association with Mid-Atlantic upper low).
Otherwise, drier and stable air will preclude the need for pops
elsewhere, while lower thickness values will support max temps
slightly below climo.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
As of 200 PM EDT Friday: A deep trough will extend southwest from a
closed low pressure system over the DelMarVa area through the
western Carolinas Saturday night through Sunday. Deeper moisture
will wrap southward around the back side of the system to contribute
some cloudiness to the northern tier, but any shower chances
Saturday night into early Sunday look rather low. Northerly cold
advection flow will maximize during this period with thicknesses
bottoming out across the region to produce min/max temps 1 to 2
categories below climo.

Meanwhile, at the surface sprawling high pressure will build from
the upper Midwest to the east coast and nose southward through the
western Carolinas and northeast Georgia through Monday. Modest
surface dewpoint recovery will begin in southwest sections by Monday
afternoon, but the potential for any southwest mountain ridge
diurnal convection looks quite limited.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
As of 210 PM EDT Friday: The eastern trough will broaden in the
Tuesday to Friday timeframe as it gets reinforced by rounds of
digging shortwave energy arriving from Manitoba and Ontario. Under
the developing broad ridge, the airmass over the southeast will
continue to modify through the week with temperatures gradually
returning to normal. Diurnal convective coverage from terrain
forcing will increase each afternoon Tuesday through Thursday.
Deeper moisture will pool ahead of a cold front approaching from the
northwest on Friday to generate above climo PoPs.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Showers and storms moving off the Blue Ridge
are expected to expand in coverage and intensity as they move east
across the area through late afternoon. Tempos for TSRA are included
at all terminals...beginning now at all sites except KCLT, and at
20Z at KCLT. Occl visby and/or cig restrictions are likely during
brief periods of heavy rain. Showers and storms are expected to
diminish in coverage from late afternoon into the early evening.
However, additional activity developing ahead of a cold front over
the TN Valley may then move into the area during mid/late evening.
VCSH and Prob30s therefore linger into the early part of the
overnight at all TAF sites. The concern then shifts to the potential
for fog and/or stratus late tonight, as low level moisture remains
plentiful, and mid/upper levels begin to dry. For the time being,
late night/early morning restrictions are confined to KAVL/KHKY, but
more widespread restrictions are certainly possible. SW winds may
gust at times this afternoon, diminishing to 5-10 kts by mid-evening
or so. Winds then shift to the NW at most terminals by mid-morning,
with speeds of 5-10 kts expected (10-15 kts and possibly gusty at
KAVL).

Outlook: Drier air will filter in from the north behind a passing
cold front this weekend. Chances for morning fog and stratus will
also be possible mainly in the mountain valleys. A typical
summer-time pattern is expected to return by the middle of next week.

Confidence Table...

            20-02Z        02-08Z        08-14Z        14-18Z
KCLT       High 100%     High  87%     High  90%     High 100%
KGSP       High 100%     High 100%     High  95%     High 100%
KAVL       High  98%     High  86%     Med   76%     High  98%
KHKY       High  86%     High  97%     Med   75%     High 100%
KGMU       High 100%     High  95%     High  94%     High 100%
KAND       High  98%     High  94%     Med   68%     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...HG
NEAR TERM...JDL/Wimberley
SHORT TERM...HG
LONG TERM...HG
AVIATION...JDL

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
346 PM EDT Fri Jul 28 2017

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-501>510-
SCZ001>007-010>012-019-292000-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Graham-Northern Jackson-Macon-
Southern Jackson-Transylvania-Henderson-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-Anderson-Abbeville-Laurens-Greenwood-
346 PM EDT Fri Jul 28 2017

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

.DAY ONE...This Afternoon and Tonight.

Isolated thunderstorms may redevelop from the west along an
approaching cold front later this evening. A few cloud to ground
lightning strikes will be possible.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

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

.SPOTTER INFORMATION STATEMENT...

None.

NCZ035>037-056-057-068>072-082-SCZ008-009-013-014-292000-
Alexander-Iredell-Davie-Catawba-Rowan-Cleveland-Lincoln-Gaston-
Mecklenburg-Cabarrus-Union-Cherokee-York-Chester-
346 PM EDT Fri Jul 28 2017

This Hazardous Weather Outlook is for piedmont North Carolina and the
eastern Upstate of South Carolina.

.DAY ONE...This Afternoon and Tonight.

Numerous thunderstorms will sweep east through the Interstate 77
corridor in the piedmont of the Carolinas late this afternoon through
early this evening. The main threat will be damaging wind gusts in
excess of 60 mph. Frequent cloud-to-ground lightning will occur with
these thunderstorms and the heaviest downpours could produce isolated
flooding of low-lying and poor drainage areas.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

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

.SPOTTER INFORMATION STATEMENT...

Spotters are asked to relay any reports of severe weather or flooding
to the National Weather Service.

HG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
455 PM EDT FRI JUL 28 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     TSTM WND DMG     3 N ROCK HILL           34.98N 81.02W
07/28/2017                   YORK               SC   FIRE DEPT/RESCUE

            FIRE DEPT/RESCUE REPORTED LARGE TREES AND POWER LINES
            DOWN ON INDIA HOOK RD NORTH OF CELANESE

&&

LEC

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
456 PM EDT FRI JUL 28 2017

NCZ036-037-057-282130-
Rowan NC-Davie NC-Iredell NC-
456 PM EDT FRI JUL 28 2017

...STRONG THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT DAVIE...
IREDELL AND ROWAN COUNTIES UNTIL 530 PM EDT...

At 456 PM EDT, Doppler radar indicated strong thunderstorms with
intense lightning along a line extending from 12 miles southwest of
Yadkinville to 7 miles east of Statesville to 6 miles northeast of
Huntersville, and moving east at 30 mph.

Locations to be impacted include...
Salisbury, Statesville, Mocksville, Kannapolis, Mooresville, China
Grove, Spencer, Landis, Enochville and Granite Quarry.

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.

Torrential rainfall may flood areas with poor drainage, such as
ditches and underpasses. Avoid these areas and do not cross flooded
roads. Water levels of small streams may also rise rapidly. Seek
higher ground if threatened by flood waters.

Frequent lightning is occurring with these storms. 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 storms approach.

These storms 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 3550 8038 3551 8091 3575 8087 3605 8101
      3604 8049 3606 8046 3593 8037 3589 8037
      3588 8042 3587 8039 3585 8039 3585 8042
      3583 8043 3583 8046 3584 8047 3583 8049
      3579 8048 3577 8045 3574 8046 3572 8035
TIME...MOT...LOC 2056Z 255DEG 25KT 3605 8086 3578 8075 3551 8079

RWH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
457 PM EDT FRI JUL 28 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0455 PM     TSTM WND DMG     2 SSW CHARLOTTE         35.17N 80.85W
07/28/2017                   MECKLENBURG        NC   COUNTY OFFICIAL

            TREES AND POWER LINES DOWN ON VALLEY STREAM ROAD.

&&

HG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
503 PM EDT FRI JUL 28 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0455 PM     TSTM WND DMG     3 S UPTOWN CHARLOTTE    35.18N 80.85W
07/28/2017                   MECKLENBURG        NC   LAW ENFORCEMENT

            LAW ENFORCEMENT REPORTED BRANCHES DOWN ON POWER LINES
            RESULTING IN A FIRE ON WEST FIELD RD.

&&

LEC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
507 PM EDT FRI JUL 28 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 PM     TSTM WND DMG     4 ESE UPTOWN CHARLOTTE  35.20N 80.79W
07/28/2017                   MECKLENBURG        NC   LAW ENFORCEMENT

            LAW ENFORCEMENT REPORTED A TREE DOWN LEANING ON POWER
            LINES ON COMMONWEALTH AVE.

&&

LEC

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