Severe Thunderstorm Warning 206, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
243 PM EDT Wed Jun 27 2018

.SYNOPSIS...
Strong to severe thunderstorms will persist into this evening but
activity will dissipate overnight.  A weak cold front approaches the
area Thursday and additional showers and thunderstorms are expected.
Behind the front, precip chances decrease through Saturday but heat
and humidity will persist.  Shower and thunderstorm chances increase
Sunday through Wednesday as another front approaches the area.

&&

.NEAR TERM /THROUGH THURSDAY/...
As of 225 PM: The latest RADAR mosaic is showing sct convection
already over much of the higher terrain with some cells beginning
to move over the NC Foothills and SC Upstate. Convective coverage
will continue to spread over the next few hours per the latest
CAM guidance. Sfc-based CAPE still looks plentiful over the area,
and effective shear is expected to peak between 20-30 kt, with
predominately WLY winds throughout the profiles. This should be
enough to allow linear organization with the developing clusters,
and more than one round of convection is certainly possible. As
noted previously, the NAM DCAPE and the sfc-midlevel Theta-E lapse
rates are more favorable for severe storms than those from the GFS.
Otherwise, an upper trough will move over the lower Ohio Valley
tonight and early tomorrow as a sfc cold front moves thru the area.
Max temps today should top out around normal for late June with
highs tomorrow reaching a few degrees above normal. Tomorrow should
be less active overall with drier profiles in place and more of a
downslope component to the low-lvl flow. In addition, the upper
trof axis should be east of the CWFA by tomorrow afternoon. Thus
upper lvl support will be considerably weaker over the area.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
As of 230 PM EDT Wednesday: We are still on track to welcome
another weak frontal boundary into the region Thursday night
into early Friday as the upper level trough axis exits the East
Coast.  Surface winds will veer from westerly to northerly and
northeasterly as the front drops from north to south through our
area, clearing the region later Friday morning as high pressure
builds into the Mid-Atlantic.  The long-advertised heat ridge
enters the mid-Mississippi River Valley behind the departing
trough which will allow us to maintain min and max temperatures
about 4-8 degrees above normal; however, the northerly low-level
flow will allow slightly drier air (dewpoints in the upper 60s)
to infiltrate the region and reduce humidity.  Subsidence-induced
warm air continues to be advertised in the 600-800mb layer aloft
which will aid in suppressing convective activity across much
of the Piedmont.  Regardless, we continue to carry a chance of
convection along our southern and western counties closer to the
frontal boundary and over the mountains where typical orographic
forcing is anticipated to overcome the weak cap.

Northeasterly near-surface flow continues into Saturday as high
pressure slowly moves off the Delmarva coastline, keeping us along
the ridge axis.  Aloft, the heat ridge centers over the Mid-Atlantic
and the low to mid-level flow veers easterly, which appears to
advect some Atlantic moisture into the region, especially along
the southern and western counties, and the column moistens below
600mb in response.  Some mid-level inhibition via the subsident warm
nose remains but the "moist" easterly flow combined with respectable
MUCAPE values increases diurnal PoPs slightly on Saturday especially
south and west, furthest away from the upper-level ridge center.
There will be little change in temperatures and a slight uptick in
humidity, especially across the NC Piedmont which will keep heat
indices in the upper 90s to near 100, but below advisory criteria.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 230 PM EDT Wednesday: As the upper-level ridge center slides
off the East Coast heading into Sunday, the Deep South is in a
weakness between that center and a second height maximum over the
the Southern Plains.  One or two weak upper lows may develop in
this weakness which may enhance moisture flux and forcing Sunday
into Monday, but overall the general pattern will not change as
southeasterly low-level flow will persist around the base of the
high pressure center over the western Atlantic.  Persistent moisture
flux into the region combined with upslope flow will incrementally
increase PoP on Sunday and Monday as mid-level subsidence warming
weakens and total moisture content in the column increases.
Overall, we are expecting flow throughout the column to be very
weak which means as PWs increase to above 1.50" Sunday and Monday
the threat for locally heavy rainfall and isolated flooding will
also increase.

The most significant change in the pattern for Tuesday and
Wednesday is the approach of another weak/summertime cold front
which is associated with a weak shortwave trough.  The trough
will concurrently dampen the East Coast ridge.  Guidance is in
generally good agreement on this frontal approach and the area-wide
increase in PoPs as the associated forcing influences coverage.
As the parent low departs New England heading into Wednesday the
front may wash out before it reaches our area but the proximity
of the remnant boundary will maintain high-end chance (Piedmont,
foothills) to likely PoPs (mountains) into Wednesday afternoon.
Overnight PoPs during Tuesday and Wednesday night will remain
elevated given the moisture and weak forcing in place.  The heavy
rainfall threat also persists as the mid-level flow from Monday
weakens further in advance of the shortwave trough.

There will not be much change in above-normal temperatures or
muggy dewpoints during the period; however, the increase in cloud
cover Tuesday and Wednesday as a result of increased convective
coverage will shave 1-3 degrees off the highs both days returning
us to near-normal temperatures for early July.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
At KCLT and elsewhere: Expect mostly VFR conditions to prevail thru
18z TAF period. Exceptions include TEMPOs for TSRA this afternoon
and evening with another round of reduced visby for KAVL tomorrow
morning from roughly 10 to 13z. I have visby going down to MVFR at
KAVL, but they could see brief IFR visby and cigs as well. Otherwise,
we can expect another round of scattered to numerous showers and
thunderstorms this afternoon/evening with some organization possible
especially across the Foothills and Piedmont. Convective potential
dwindles after roughly 00z, although some activity could linger into
the late night and overnight. Tomorrow should be less active overall
with drier profiles in place and less upper-lvl support over the area.

Outlook: An upper ridge building over the Eastern CONUS is expected
to reduce diurnal convection late this week into early next week.
Patchy morning fog and/or low stratus will continue to be an issue
in mountain valleys and/or locations with wet ground.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High  98%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High  98%
KHKY       High  99%     High 100%     High 100%     High  98%
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...JMP
LONG TERM...JMP
AVIATION...JPT

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
445 AM EDT Wed Jun 27 2018

GAZ010-017-018-026-028-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>010-013-014-280845-
Rabun-Habersham-Stephens-Franklin-Hart-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-Chester-
445 AM EDT Wed Jun 27 2018

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

.DAY ONE...Today and Tonight.

Scattered to numerous thunderstorms are expected to develop again
this afternoon and evening. Some of these storms may become severe
with damaging winds as the main threat, but large hail cannot be
ruled out. Frequent cloud-to-ground lightning and brief heavy rain
can be expected as well.

.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...

Skywarn spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

GAZ029-SCZ011-012-019-280845-
Elbert-Abbeville-Laurens-Greenwood-
445 AM EDT Wed Jun 27 2018

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

.DAY ONE...Today and Tonight.

Scattered to numerous thunderstorms are expected to develop again
this afternoon and evening. Some of these storms may become severe
with damaging winds as the main threat, but large hail cannot be
ruled out. Frequent cloud-to-ground lightning and brief heavy rain
can be expected as well.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

..Thursday...No hazardous weather is expected at this time.
..Friday...Excessive heat possible.
..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...

Skywarn spotters are requested to forward any reports of large hail,
damaging winds, tornadoes, or flash flooding to our office.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
320 PM EDT WED JUN 27 2018

GAZ010-017-SCZ001-271945-
Rabun GA-Habersham GA-Oconee Mountains SC-
320 PM EDT WED JUN 27 2018

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN HABERSHAM...RABUN AND
NORTHWESTERN OCONEE COUNTIES UNTIL 345 PM EDT...

At 320 PM EDT, Doppler radar was tracking a strong thunderstorm 11
miles north of Clarkesville, or 4 miles southwest of Lake Burton,
moving east at 25 mph.

Locations to be impacted include...
Clayton, Mountain City, Tiger, Dillard, Sky Valley, Tallulah Falls,
Lake Rabun, Lake Burton, Moccasin Creek State Park and Lakemont.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This storm 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 3482 8365 3484 8366 3487 8365 3500 8335
      3500 8311 3480 8315 3476 8332 3463 8339
      3468 8364 3471 8364 3473 8362 3476 8363
      3480 8368
TIME...MOT...LOC 1920Z 275DEG 23KT 3477 8359

MOORE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
334 PM EDT WED JUN 27 2018

GAZ010-NCZ063>065-SCZ001>003-005-272000-
Rabun GA-Transylvania NC-Henderson NC-Southern Jackson NC-
Pickens Mountains SC-Greater Pickens SC-Oconee Mountains SC-
Greenville Mountains SC-
334 PM EDT WED JUN 27 2018

...STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN RABUN...SOUTHERN
TRANSYLVANIA...SOUTH CENTRAL HENDERSON...SOUTH CENTRAL JACKSON...
NORTHWESTERN GREENVILLE...NORTHERN PICKENS AND NORTHEASTERN OCONEE
COUNTIES UNTIL 400 PM EDT...

At 334 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 6 miles south of Brevard to 14 miles north of
Walhalla, and moving east at 30 mph.

Locations to be impacted include...
Brevard, Pickens, Slater-Marietta, Rosman, Salem, Lake Toxaway,
Jocassee Gorges, Devils Fork State Park, Table Rock State Park and
Caesars Head State Park.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3494 8325 3500 8316 3500 8311 3502 8313
      3526 8276 3519 8235 3499 8249 3497 8253
      3494 8252 3487 8257 3484 8277
TIME...MOT...LOC 1934Z 269DEG 25KT 3515 8277 3498 8310

MOORE

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