Hail and Damaging Wind in North Carolina, May 20, 2018

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
253 PM EDT Sun May 20 2018

.SYNOPSIS...
A moist air mass will remain atop the region through at least
Tuesday. This will result in a continued high chance of showers and
storms each afternoon and evening.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 245 PM EDT: Convection firing across the higher terrain as
expected by earlier trends in satellite imagery, and recently
convection has started to develop into a corridor of higher
instability greater than 2500 J/kg on the SPC mesoanalysis. Will
not rule out a few severe storms over the corridor from the Blue
Ridge Escarpment to the I-85 corridor as dCAPE has generally
climbed above 800 J/kg in that area. The storms should fade in
the early evening as the instability is consumed. Temps look ok.

Kind of difficult to differentiate one day to the next in this air
mass as very little changes in the synoptic scale over the next 24
hours or so. Persistence looks like a good forecast. Still think
convection will mostly ash out in the mid/late evening and then
we will have a lull during the pre-dawn hours through mid-morning
Monday. We could end up with some patchy dense fog in places
that have good rain this afternoon. Low temps will be seasonally
mild once again. On Monday, destabilization will depend on when
any lingering convective debris moves away or dissipates, but in
general it should be fairly early in the day over the mtns. The
model guidance is not terribly keen on developing convection across
the western Piedmont and Upstate on Monday afternoon, however. Will
not make major changes to the precip probability in that regard,
but will trend a bit downward over the east in the afternoon. High
temps will be just above normal.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 245 PM EDT Sunday: The forecast area will be between a weak
upper low over GA and a subtropical anticyclone off the Southeast
Coast on Tuesday. This will keep a deep, moist southerly flow over
the area as surface high pressure sits off the Southeast coast as
well. Instability will be weak, but the southerly flow and moist air
mass will create conditions favorable for diurnal convection. Given
the weak instability and moist profiles, expect heavy rainfall would
be the greater threat than severe storms. Highest PoP will be across
the mountains, western Upstate, and NE GA, but the rest of the area
will see good chance values. The upper low washes out Wednesday and
the subtropical anticyclone is suppressed as a short wave trough
passes by to our north. This short wave does push a frontal boundary
into the area on Wednesday. The short wave also creates increasing
lapse rates with cooling mid level temps. Dry mid level air filters
in as well increasing surface delta theta-e values. DCAPE values
remain modest, but expect severe chances to creep up with the
moderate instability and drier mid levels. That said, heavy rainfall
cannot be ruled out given the good coverage and frontal boundary.
Lows remain nearly steady 5 to 10 degrees above normal. Highs near
normal Tuesday rise to around 5 degrees above normal Wednesday.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 235 PM EDT Sunday: The medium range forecast period begins
Wednesday night, as an overall unsettled weather pattern remains on
tap through into next week. With the Bermuda High once extended into
the Southeast retreating back to the east and an upper trough slowly
exiting from the NE and Canada off to the east, weakening upper
ridge is progged to move out of the central plains and over the
eastern half of the US on Thursday. As sfc high manages to build
south into the OH Valley before being pushed eastward and out to
sea, a weak sfc trough looks to meander around and just south of the
FA Thursday into early Friday. With a very moist airmass in place as
PWATs remain well above one inch, low-level SW flow returns on
Friday as weak upper ridging returns to the north. Expect diurnal
convection to be a daily occurrence as dewpoints remain in the mid
to upper 60s and severe weather parameters, while not overly
impressive, remain somewhat on the map of interest. Thus, would not
entirely rule out an isolated severe storm any of the days, but the
bigger concern will be the continued potential threat for periods
heavy rainfall and localized flash flooding.

Into the weekend, as it has been mentioned over the past few days,
things could get interesting and even more complicated. While
another system looks to move into the upper midwest and gradually
approach the area just past the medium range forecast period,
guidance continues to hint at the possibility of a developing
tropical system. However, plenty of discrepancy remains between the
models so nothing is set in stone. Whether it develop in the GOM or
on the east coast of FL, or not at all, moisture will continue to
infiltrate into the area, and thus the continuation of an unsettled
weather pattern.

Temperatures each day will climb into the low to mid 80s (cooler
across the mountains), with overnight lows above normal.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
At KCLT and elsewhere: Low clouds with bases generally in the
range of 020-025 continue to scatter out across the region
early this afternoon. Cannot rule out a brief MVFR ceiling away
from ongoing convection, but this detail will not be included
for brevity. Instead, prefer to employ a 3-4 hr TEMPO to handle
thunderstorm restrictions later this afternoon at all sites other
than KAND. The showers and storms should diminish fairly early
this evening with only convective debris beyond 23Z-01Z. Locations
that see rain this afternoon/evening will have a good chance at
a fog restriction in the pre-dawn hours Monday if recent past is
any indication. All sites get a short window of MVFR visibility
around daybreak to account for this. Otherwise, Monday looks to
be nearly a copy of today. Wind should remain light S/SW apart
from thunderstorm outflows today, then light/variable overnight,
and SW again Monday.

Outlook: The unsettled weather pattern will continue into the first
half of the week with flight restrictions possible each day around
isolated/scattered showers and storms.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High 100%     High 100%     High 100%     High  92%
KGSP       High 100%     High 100%     High  89%     High  86%
KAVL       High 100%     High 100%     High  82%     High  98%
KHKY       High 100%     High 100%     High  93%     High  88%
KGMU       High 100%     High 100%     High  84%     High  81%
KAND       High 100%     High  99%     Med   74%     High  80%

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...ARK
NEAR TERM...PM
SHORT TERM...RWH
LONG TERM...SGL
AVIATION...PM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
335 PM EDT Sun May 20 2018

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-211945-
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-
335 PM EDT Sun May 20 2018

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

.DAY ONE...Tonight.

Scattered thunderstorms will continue into the evening across the
area. Brief heavy rain with localized flash flooding, small hail,
and lightning are possible. Gusty winds from thunderstorms could
blow down a few trees due to saturated soils.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

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

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
343 PM EDT SUN MAY 20 2018

NCZ508>510-SCZ003-007-202015-
Greater Rutherford NC-Polk Mountains NC-Eastern Polk NC-
Greenville Mountains SC-Spartanburg SC-
343 PM EDT SUN MAY 20 2018

...A CLUSTER OF STRONG THUNDERSTORMS WITH INTENSE LIGHTNING WILL
IMPACT CENTRAL RUTHERFORD...POLK...NORTHEASTERN GREENVILLE AND
NORTHWESTERN SPARTANBURG COUNTIES UNTIL 415 PM EDT...

At 343 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning near Columbus, moving south at 15 mph.

Locations to be impacted include...
Columbus, Landrum, Tryon, Campobello, Lake Bowen, Tigerville, Saluda,
Chimney Rock State Park, Mill Spring and Glassy Mountain.

In addition to intense lightning, wind gusts 40 to 50 mph and pea
size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 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 3542 8206 3509 8189 3506 8239 3531 8232
      3531 8231 3537 8228 3540 8225 3540 8219
      3541 8218
TIME...MOT...LOC 1943Z 001DEG 11KT 3529 8219

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
346 PM EDT SUN MAY 20 2018

GAZ017-018-202015-
Stephens GA-Habersham GA-
346 PM EDT SUN MAY 20 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT WESTERN
STEPHENS AND HABERSHAM COUNTIES UNTIL 415 PM EDT...

At 345 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning over Clarkesville, moving south at 10 mph.

Locations to be impacted include...
Clarkesville, Toccoa, Cornelia, Baldwin, Demorest, Mount Airy, Alto,
Tallulah Falls, Raoul and Hollywood.

In addition to intense lightning, wind gusts up to 40 mph will be
possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 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 3454 8362 3460 8365 3462 8364 3465 8366
      3468 8364 3471 8364 3473 8348 3474 8342
      3473 8340 3473 8338 3472 8336 3447 8334
      3446 8340 3448 8347 3449 8354 3445 8359
      3445 8363 3451 8367
TIME...MOT...LOC 1945Z 001DEG 10KT 3462 8353

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
355 PM EDT SUN MAY 20 2018

NCZ064-065-SCZ002-003-202030-
Transylvania NC-Henderson NC-Pickens Mountains SC-
Greenville Mountains SC-
355 PM EDT SUN MAY 20 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
SOUTHEASTERN TRANSYLVANIA...SOUTH CENTRAL HENDERSON...NORTHWESTERN
GREENVILLE AND NORTHERN PICKENS COUNTIES UNTIL 430 PM EDT...

At 354 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 11 miles north of Pickens, or near Table Rock State
Park, moving south at 10 mph.

Locations to be impacted include...
Brevard, Slater-Marietta, Rosman, Jocassee Gorges, Pleasant Ridge
State Park, Jones Gap State Park, Dupont State Forest, Table Rock
State Park, Caesars Head State Park and Keowee Toxaway State Park.

In addition to intense lightning, wind gusts up to 50 mph and pea
size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 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 3521 8284 3529 8253 3503 8244 3491 8288
TIME...MOT...LOC 1954Z 348DEG 8KT 3505 8273

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
406 PM EDT SUN MAY 20 2018

NCZ509-510-SCZ003-006-007-202030-
Polk Mountains NC-Eastern Polk NC-Greenville Mountains SC-
Spartanburg SC-Greater Greenville SC-
406 PM EDT SUN MAY 20 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT SOUTHERN
POLK...NORTHEASTERN GREENVILLE AND NORTHWESTERN SPARTANBURG COUNTIES
UNTIL 430 PM EDT...

At 406 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 8 miles south of Columbus, or near Campobello,
moving south at 15 mph.

Locations to be impacted include...
Columbus, Boiling Springs SC, Landrum, Inman, Tryon, Campobello, Lake
Bowen, Tigerville, Lake Robinson and Gowensville.

In addition to intense lightning, wind gusts up to 55 mph and pea
size hail 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 3528 8227 3528 8205 3502 8193 3502 8238
TIME...MOT...LOC 2006Z 005DEG 13KT 3513 8217

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
417 PM EDT SUN MAY 20 2018

NCZ035-056-502-504-202045-
Greater Burke NC-Greater Caldwell NC-Alexander NC-Catawba NC-
417 PM EDT SUN MAY 20 2018

...A CLUSTER OF THUNDERSTORMS WILL IMPACT WESTERN CATAWBA...
ALEXANDER...SOUTHEASTERN CALDWELL AND SOUTHEASTERN BURKE COUNTIES
UNTIL 445 PM EDT...

At 417 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms along a line extending from 4 miles south of Boomer
to 6 miles southeast of Morganton, and moving southeast at 10 mph.

Locations to be impacted include...
Hickory, Taylorsville, Lenoir, Morganton, Longview, Sawmills, Granite
Falls, Valdese, Bethlehem and Hudson.

Wind gusts up to 45 mph and pea size hail will be possible in these
areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

LAT...LON 3604 8139 3602 8135 3600 8133 3603 8127
      3604 8119 3603 8117 3604 8113 3603 8107
      3604 8103 3599 8101 3557 8150 3558 8171
      3561 8172 3561 8177 3605 8141
TIME...MOT...LOC 2017Z 305DEG 11KT 3600 8122 3565 8165

SGL

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
423 PM EDT SUN MAY 20 2018

NCZ064-065-509-510-SCZ002-003-005>007-010-202100-
Transylvania NC-Henderson NC-Polk Mountains NC-Eastern Polk NC-
Pickens Mountains SC-Greater Pickens SC-Anderson SC-
Greenville Mountains SC-Spartanburg SC-Greater Greenville SC-
423 PM EDT SUN MAY 20 2018

...A CLUSTER OF THUNDERSTORMS WITH INTENSE LIGHTNING WILL IMPACT
SOUTHEASTERN TRANSYLVANIA...SOUTH CENTRAL HENDERSON...SOUTHERN
POLK...GREENVILLE...NORTHWESTERN SPARTANBURG...NORTH CENTRAL ANDERSON
AND CENTRAL PICKENS COUNTIES UNTIL 500 PM EDT...

At 423 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms with intense lightning along a line extending from
11 miles northwest of Spartanburg to 6 miles north of Pickens, and
moving south at 10 mph.

Locations to be impacted include...
Greenville Downtown, Spartanburg, Easley, Pickens, Greenville
Eastside, West Greenville, Greer, Taylors, Berea and Welcome.

In addition to intense lightning, wind gusts up to 50 mph and half
inch hail 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 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.

&&

LAT...LON 3515 8275 3526 8197 3525 8196 3519 8197
      3518 8195 3485 8189 3473 8280
TIME...MOT...LOC 2023Z 351DEG 8KT 3506 8208 3498 8270

SGL