Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
245 PM EDT Mon May 7 2018

.SYNOPSIS...
A weak cold front moves off the Carolina coast early tonight.
Expect mountain showers and thunderstorm chances to continue Tuesday
and Wednesday on the upslope side of weak high pressure which will
keep temperatures near normal through mid-week.  Greater precip
chances arrive for Thursday with an approaching front and scattered
diurnal showers and thunderstorms are possible through the weekend
as temperatures warm to well-above normal.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 240 PM EDT Monday: Synoptic scale guidance keeps the bulk of
the convection this afternoon and evening across the mountains while
the CAM guidance shows a secondary max developing across the NC
foothills moving into the NC piedmont and eastern Upstate during the
early evening. Have kept the highest PoP across the mountains where
there is good agreement, but did allow chance PoP to spread across
the NC foothills to the western Piedmont but just short of most of
the CLT metro area. Slight chance PoP spreads across most of the
rest of the forecast area before retreating to the mountains and
upslope Blue Ridge areas overnight. CAPE values currently remain
weak but are approaching moderate levels across the mountains. DCAPE
values remain weak with low bulk shear values. The low freezing and
wet bulb zero levels still keep an isolated severe storm in play,
but overall chance is low. Slow moving or training cells are a
possibility, but chance of excessive rainfall is also low.

As mentioned above, precip chances will retreat to the mountains and
upslope areas of the Blue Ridge overnight. This follows the passage
of a weak back door cold front and high pressure building in from
the northeast behind the front. A moist easterly low level flow
develops as the high moves in and low level moisture lingers across
the area. There will be an increase in low clouds across those areas
as well which may spread east and south through daybreak before
lifting and scattering during the day. Precip chances will continue
to favor the mountains and Blue Ridge during the day as low level
moisture and upslope flow remain in place and drier air and a weak
subsidence inversion develops outside of the mountains. Lows tonight
will be near normal mountains and around 5 degrees above normal
elsewhere. Highs Tuesday will be near to a couple of degrees below
normal.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 230 PM EDT Monday: A shortwave ridge will ripple across the
area on Wednesday, with a following trough right behind it for
Thursday. The forecast area looks fairly stable with just 200-300
J/kg of SBCAPE across the high terrain on Wednesday. Despite this,
guidance still has slight CHC to low-end CHC PoPs, and this may be
overdone. Highs will be slightly above normal.

A cold front associated with the upper trough will approach the area
from the NW on Thursday and should provide some moisture and forcing
for better coverage of convection in the aftn. Models generally
agree on SBCAPE reaching 800-1200 J/kg in the mountains with lower
amounts in the foothills and piedmont. Bulk shear still looks
unimpressive (generally 20-30 kts in the 0-6 km layer). So severe
potential doesn't look that great. But cannot rule out a few
marginally severe storms. Temps will continue their warming trend,
with highs in the mid-UPR 80s across the piedmont and some LWR 80s
in the mountain valleys.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 245 PM Monday: Per latest guidance, continue to anticipate an
unsettled weather pattern through the medium range forecast period,
which begins Thursday night.

As an upper trough continues to spin and push eastward north of the
Great Lakes and New England Thursday night into Friday, sfc trough
is expected to push through the Carolinas overnight, with scattered
showers and thunderstorms becoming isolated in nature. As the
subtropical ridge builds in across the Southeast Friday and through
into the weekend, a few impulses are progged to move within the
residual weak upper trough. At the same time, a gulf system across
the FL panhandle is expected to become somewhat organized (the GFS
depicting a closed 500 mb low - the ECWMF not as defined) and slowly
move northward into the Carolinas this weekend. While the overall
better forcing will stay well north of the FA as a frontal boundary
is expected to remain draped across the OH Valley, the
aforementioned sources of energy will allow for weak upper forcing
across the area. This along with available low level moisture and
daytime heating, anticipate diurnal isolated to scattered showers
and thunderstorms through into Monday, with another system progged
to move out of the Rockies into the Plains, bringing a cold front to
the Southeast just past the forecast period.

Expect temperatures to remain well above normal with high
temperatures anticipated to soar into the upper 80s/around 90
degrees south of the I-85 corridor each day. Saturday will be the
closest day to any high temperature records (CLT - 95 degrees set in
1916), but even then, anticipate that overall max temperatures will
fall just short of any records. Overnight lows will remain in the
60s across the Upstate and NW Piedmont, cooler across the mountains.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
At KCLT and Elsewhere: Convection developing across the higher
terrain will continue through the afternoon and early evening. Have
VCTS at KAVL and KHKY where chance is highest. Cannot rule out a
cell nearby the other TAF sites, but chance too low to include for
now. Elsewhere, generally sct low VFR and bkn mid or high cloud
through the afternoon. Low level moisture and upslope flow will
create low VFR to MVFR cigs overnight. May be some showers around,
but chance too low for TAF mention. KCLT has the least chance of
either, so sct low VFR remains in place. The low cigs will lift or
scatter out through the morning with low VFR cigs likely lingering
at KAVL. Generally NE wind this afternoon continues overnight but
weakens, then picks back up with mixing Tuesday morning.

Outlook: The secondary front will settling just south of the
area on Tuesday. Slight chances for showers and thunderstorms will
persist over the area thru mid-week with some temporary restrictions
possible each day.

Confidence Table...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High 100%
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...DEO
NEAR TERM...RWH
SHORT TERM...ARK
LONG TERM...SGL
AVIATION...RWH

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
639 AM EDT Mon May 7 2018

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-081045-
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-
639 AM EDT Mon May 7 2018

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

.DAY ONE...Today and Tonight.

Isolated to scattered thunderstorms will develop this afternoon and
evening across the region, beginning over the mountains around midday
and then expanding east of the Blue Ridge in the late afternoon.
Cloud-to-ground lightning, gusty winds, and brief heavy downpours
will be the main threats. One or two storms might become strong
enough to produce large hail and damaging wind gusts. The storms
should weaken late this evening.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

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

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
308 PM EDT MON MAY 7 2018

NCZ053-065-071945-
Buncombe NC-Henderson NC-
308 PM EDT MON MAY 7 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
NORTHEASTERN HENDERSON AND SOUTH CENTRAL BUNCOMBE COUNTIES UNTIL 345
PM EDT...

At 307 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 8 miles southeast of Downtown Asheville, or near
Fairview In Buncombe County, moving south at 15 mph.

Locations to be impacted include...
Downtown Asheville, East Asheville, Arden, Fletcher, Fairview In
Buncombe County, Skyland, B.R. Parkway-Nc Arboretum To East
Asheville, Biltmore Forest, Warren Wilson College and Bat Cave.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 3544 8228 3543 8227 3542 8227 3540 8252
      3560 8255 3561 8242
TIME...MOT...LOC 1907Z 350DEG 11KT 3553 8243

SGL