Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
305 PM EDT Sat Jul 1 2017

.SYNOPSIS...
High pressure centered over the western Atlantic and a broad upper
level trough will continue over the eastern part of the nation into
the early part of the week.  A weak cold front lingers west to east
over our region Sunday into early week helping in the generation of
showers and storms. Another upper level disturbance will approach
our area later in the week enhancing the coverage of showers and
storms.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 2:10pm EDT Saturday:  Currently, some showers and
thunderstorms have fired only a weak surface boundary that runs
northeast to southwest along the foothills from Iredell to Polk
counties.  These storms are expected to move ENE through the
afternoon.  More storms are expected to enter western parts of the
CWA later this afternoon/evening as an upper level disturbance moves
eastward across the area.  An area of thunderstorms near severe
intensity currently exists in central Tennessee with this wave, and
these showers will continue eastward, reaching northeast Georgia and
western North Carolina by 6pm, with some earlier showers popping up
ahead of the main activity also possible.  There is some chance for
severe outflows from any of these storms, along with brief
torrential rainfall and heavy lightning.

Clearing skies have allowed temperatures to warm to near or above
seasonal normals.  Moisture is still in place and this warming has
resulted in MLCAPE increasing to the highest levels seen this week
at 1500 to 2000 j/kg.  Shear is still weak, but with higher CAPE,
some strong outflows will be a risk this afternoon.

Following passage of shortwave, surface trough also moves eastward
and low-level winds veer to become more northwesterly.  This will
help to dry things a little bit with dewpoints on Sunday several
degrees below Saturday.  With reduced moisture, surface boundary
east of the area, and a lack of shortwave activity, POPs and
thunderstorm chances are much lower on Sunday. With less cloudy and
drier conditions on Sunday, highs will warm into the low 90s in
piedmont areas to mid 80s in the mountains.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 230 PM EDT Sunday: At the start of this forecast cycle
the south and west sections of our forecast area (FA) will
already be firmly in an airmass change. That trend should shift
east through mid week.

Meanwhile an upper level ridge will remain poised off the eastern
seaboard, and the westerlies displaced well north, through this
period. This places our FA in a rather non-descript regime with
small scale features noted on all the models, at different times and
places.

In the early part of the forecast we will allow Monday's evening
convection to wane in parts of our western FA, albeit a little
slower with a moist airmass.

Otherwise there appears to be consistency from the models with the
idea of scattered convection firing in the western half of our FA
Tuesday along a weak surface convergence zone. That convection
should then drift/develop east and south. At this point we will have
minimal or no POPS in our far east, in comparison to high chances in
the west. SBCAPES will be amply unstable

Wednesday has the same lee side trough look, only more well defined.
The suite of models have noted this trend, and we have raised POPS
higher for Wednesday in comparison to Tuesday. Once again SBCAPES
will be high.

The overall thermal structure suggests a slight upward trend into
midweek, and we have followed those trends.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 205 PM EDT Saturday: Starting Tuesday evening with the broad
upper trough over the East and ridge centered over the Four Corners.
The nearly closed off shortwave trough will be over Missouri Tuesday
evening and moving slowly toward our region.  The GFS has a well
defined low level circulation over the Upper Savannah River Valley
Tuesday night. The EC little low pressures over the Carolinas at
that time so looks a bit active to start this medium range.  The
Missouri shortwave crosses the Ohio Valley Wednesday with more
enhancement of convection for our region especially late Thursday.
CAPE values between 2500 and 3000 late Thursday with highest values
over NE GA and Upstate SC. Some shear will also help in generating
strong storms.  The models have a fairly deep trough over the East
Coast next weekend and a big ridge from the eastern Rockies north
into Canada.  The front that moves through Thursday night should
linger just south of our area through the weekend. So the scattered
convection hangs on.

Temperatures should remain near normal and maybe Max Temps just
below if the could cover is persistent.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Currently some thunderstorms are firing along
a weak convergence boundary from north of KGSP to north of KCLT.
These showers will move ESE and increase in coverage through 0Z this
evening.  More showers and thunderstorms are expected to move into
the area after 21Z from the west associated with an upper level
disturbance.  These thunderstorms will be accompanied by divergent
outflows with highly variable and gusty winds.  Thunderstorms will
move east of the area and decline by midnight.  Some low clouds and
patchy fog are also possible Sunday morning, especially in
mountainous areas.  Overnight, surface winds will veer, becoming
more westerly to northwesterly as weak surface boundary moves out of
the area.  With somewhat dryer air, showers and clouds will be less
impactful on Sunday when conditions are expected to be VFR following
burn-off of any fog/low clouds.

Outlook: A moist and unsettled pattern will persist into early
next week, featuring mainly afternoon/evening SHRA/TSRA and areas
of nocturnal restrictions.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     Med   75%     High  92%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  99%     High  86%     High  96%
KHKY       High 100%     High 100%     High  83%     High  96%
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...DEO
NEAR TERM...WJM
SHORT TERM...TS
LONG TERM...DEO
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
513 AM EDT Sat Jul 1 2017

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-020915-
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-
513 AM EDT Sat Jul 1 2017

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

.DAY ONE...Today and Tonight.

A moist and unstable airmass will persist across the region today. By
the afternoon...strong and deep thunderstorms will develop capable
of producing heavy rainfall leading to possible localized flooding.
In addition...some of the stronger storms could generate damaging
wind gusts.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

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

.SPOTTER INFORMATION STATEMENT...

None.

Krentz

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Special Weather Statement
National Weather Service Greenville-Spartanburg SC
405 PM EDT SAT JUL 1 2017

NCZ048-049-012030-
Yancey NC-Madison NC-
405 PM EDT SAT JUL 1 2017

...STRONG THUNDERSTORMS WILL IMPACT MADISON AND NORTHERN YANCEY
COUNTIES UNTIL 430 PM EDT...

At 404 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 8 miles southeast of Greeneville to 11 miles east
of Newport, and moving east at 30 mph.

Locations to be impacted include...
Marshall, Hot Springs, Mars Hill, Ramseytown, Green Mountain, Swiss,
Faust, Allenstand, Walnut and Luck.

Wind gusts up to 45 mph, half inch hail and very heavy rainfall
rates of 1 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 3606 8234 3603 8233 3604 8230 3599 8225
      3601 8225 3599 8219 3570 8285 3579 8296
      3588 8290 3593 8292 3595 8287 3593 8281
      3600 8278 3606 8264 3603 8259 3597 8261
      3595 8257 3601 8246 3608 8240
TIME...MOT...LOC 2004Z 284DEG 29KT 3606 8273 3594 8298

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
407 PM EDT SAT JUL 1 2017

NCZ035-036-012030-
Iredell NC-Alexander NC-
407 PM EDT SAT JUL 1 2017

...A STRONG THUNDERSTORM WILL IMPACT ALEXANDER AND NORTHERN IREDELL
COUNTIES UNTIL 430 PM EDT...

At 406 PM EDT, Doppler radar was tracking a strong thunderstorm near
Taylorsville, moving east at 30 mph.

Locations to be impacted include...
Statesville, Taylorsville, Stony Point, Harmony, Love Valley,
Hiddenite, Turnersburg, Olin, Vashti and Millersville.

Wind gusts up to 45 mph, dime 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 3598 8075 3571 8094 3582 8114 3583 8114
      3583 8116 3590 8130 3603 8124 3604 8119
      3603 8117 3604 8113 3604 8111 3603 8110
      3603 8107 3604 8104
TIME...MOT...LOC 2006Z 290DEG 27KT 3597 8118

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
416 PM EDT SAT JUL 1 2017

NCZ070-071-012045-
Gaston NC-Mecklenburg NC-
416 PM EDT SAT JUL 1 2017

...STRONG THUNDERSTORMS WILL IMPACT CENTRAL MECKLENBURG AND EASTERN
GASTON COUNTIES UNTIL 445 PM EDT...

At 415 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 9 miles southwest of Downtown Concord to near
Uptown Charlotte to 8 miles northeast of Gastonia, and moving
southeast at 40 mph.

Locations to be impacted include...
Uptown Charlotte, Gastonia, Central Charlotte, Southwest Charlotte,
East Charlotte, Northwest Charlotte, Matthews, Mint Hill, Mt Holly
and Belmont.

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 3512 8066 3511 8103 3513 8105 3515 8105
      3515 8109 3539 8120 3527 8094 3533 8069
      3527 8067 3521 8055
TIME...MOT...LOC 2015Z 287DEG 33KT 3530 8069 3525 8088 3534 8105

HG