Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
801 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 750 pm: Scattered convection is becoming increasingly
concentrated along the northern Blue Ridge in North Carolina, while
activity is trending down in intensity and coverage in other areas.
The highest pops of 40-50% will therefore be reserved across the
northern NC foothills over the next couple of hours. Low freezing
levels, along with a decent percentage of overall environmental CAPE
being concentrated in the hail growth layer will continue to yield a
goodly amount of hail from the stronger storms. Would not completely
rule out a large hail report if any cell collisions occur.
Otherwise, hail will remain small in light of weak (and getting
weaker) CAPE.

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 MONDAY/...
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 /00Z TUESDAY THROUGH SATURDAY/...
At KCLT and Elsewhere: Convection continues over the high terrain
early this evening, with the most concentrated/robust activity seen
along the Blue Ridge from I-40 northward. This is the first time
since the diurnal convective cycle began that convection has shown
much of a desire to survive off the high terrain, as the activity
that moved into Upstate SC during the afternoon quickly dissipated.
As such, KHKY stands the best chance (by far) of seeing convection
over the next few hours, and the VCTS was continued there, while a
tempo for -TSRA has been added from 01-03Z. As far as the other
sites, see nothing conclusive that leads me to believe that
convection is a good bet this evening, and other than a token VCSH
at KAVL, any mention of convection has been removed from the
forecasts. Still would not completely rule out Blue Ridge convection
holding together and making a run at KCLT, but it would be 04 Z-ish
at the earliest before it would arrive there...plenty of time to
dissipate in response to diurnal cooling.

Otherwise, developing light easterly flow and lingering low level
moisture will yield some potential for low stratus late tonight/
early Tue, with fog also possible in areas that will see or have
seen rainfall this afternoon/evening. Confidence is not especially
high at this point, and other than some MVFR fog advertised in the
mtn valleys and at KHKY, we are mainly advertising SCT IFR/MVFR
clouds developing around daybreak at this point. Another round of
diurnal convection is expected Tue afternoon, but will mainly be
confined to the high terrain, where a prob30 for SHRA is advertised.

Outlook: A cold front will settle 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...JDL/RWH
SHORT TERM...ARK
LONG TERM...SGL
AVIATION...JDL

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
327 PM 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>014-019-081930-
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-
327 PM 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...This Afternoon and Tonight.

Isolated to scattered thunderstorms will continue to develop into this
evening across the region, mainly over the mountains, but with some
expansion east of the Blue Ridge in the early evening. 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.

ARK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
759 PM EDT MON MAY 7 2018

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

0740 PM     HAIL             3 N ASHFORD             35.91N 81.94W
05/07/2018  E0.75 INCH       MCDOWELL           NC   SOCIAL MEDIA

            OBSERVED ALONG HWY 221

&&

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

NCZ502-080045-
Greater Caldwell NC-
808 PM EDT MON MAY 7 2018

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL CALDWELL COUNTY
UNTIL 845 PM EDT...

At 807 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles east of Lenoir, or over Cedar Rock, moving southeast at 5 mph.

Locations to be impacted include...
Cedar Rock.

Pea size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Dime to nickel size hail can cause considerable damage to vehicles.
Consider moving vehicles to a covered storage area before the storm
arrives.

&&

LAT...LON 3595 8152 3598 8144 3592 8135 3586 8146
TIME...MOT...LOC 0007Z 318DEG 6KT 3593 8145

SGL

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

NCZ505>508-080045-
Greater Rutherford NC-McDowell Mountains NC-Rutherford Mountains NC-
Eastern McDowell NC-
814 PM EDT MON MAY 7 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL MCDOWELL AND
NORTHWESTERN RUTHERFORD COUNTIES UNTIL 845 PM EDT...

At 814 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles southwest of Marion, or 7 miles southeast of Old Fort, moving
southeast at 5 mph.

Locations to be impacted include...
Thermal City, Sugar Hill and Shingle Hollow.

Dime size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Dime to nickel size hail can cause considerable damage to vehicles.
Consider moving vehicles to a covered storage area before the storm
arrives.

&&

LAT...LON 3558 8218 3562 8209 3553 8195 3544 8214
TIME...MOT...LOC 0014Z 324DEG 6KT 3555 8211

SGL

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

NCZ051-080045-
Swain NC-
819 PM EDT MON MAY 7 2018

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL SWAIN COUNTY UNTIL
845 PM EDT...

At 819 PM EDT, Doppler radar was tracking a strong thunderstorm near
Bryson City, moving southeast at 5 mph.

Locations to be impacted include...
Bryson City, Alarka and Luada.

Dime size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Dime to nickel size hail can cause considerable damage to vehicles.
Consider moving vehicles to a covered storage area before the storm
arrives.

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 3543 8355 3546 8348 3535 8335 3530 8355
TIME...MOT...LOC 0019Z 337DEG 6KT 3539 8350

SGL

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

NCZ035-056-502-504-080100-
Greater Burke NC-Greater Caldwell NC-Alexander NC-Catawba NC-
826 PM EDT MON MAY 7 2018

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN CATAWBA...
SOUTHWESTERN ALEXANDER...SOUTHEASTERN CALDWELL AND EASTERN BURKE
COUNTIES UNTIL 900 PM EDT...

At 825 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles north of Hickory, or near Lake Hickory, moving southeast at 15
mph.

Locations to be impacted include...
Hickory, St. Stephens, Longview, Granite Falls, Bethlehem, Hildebran,
Rhodhiss, Hickory Regional Airport, Lake Hickory and Hudson.

Nickel size hail will be possible in these areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Dime to nickel size hail can cause considerable damage to vehicles.
Consider moving vehicles to a covered storage area before the storm
arrives.

&&

LAT...LON 3587 8147 3592 8135 3582 8115 3569 8143
TIME...MOT...LOC 0025Z 311DEG 15KT 3585 8135

SGL

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

NCZ035-056-502-504-080130-
Greater Burke NC-Greater Caldwell NC-Alexander NC-Catawba NC-
849 PM EDT MON MAY 7 2018

...A CLUSTER OF THUNDERSTORMS WILL IMPACT WESTERN CATAWBA...
SOUTHWESTERN ALEXANDER...SOUTHEASTERN CALDWELL AND EASTERN BURKE
COUNTIES UNTIL 930 PM EDT...

At 849 PM EDT, Doppler radar indicated the leading edge of a cluster
of thunderstorms along a line extending from 4 miles south of
Taylorsville to 4 miles southwest of Hickory, and moving south at 10
mph.

Locations to be impacted include...
Hickory, St. Stephens, Longview, Granite Falls, Bethlehem, Icard,
Hildebran, Rhodhiss, Hickory Regional Airport and Lake Hickory.

Wind gusts up to 40 mph, pea size hail and torrential rainfall rates
up to 3 inches per hour 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 3580 8113 3556 8139 3557 8139 3578 8150
      3589 8131
TIME...MOT...LOC 0049Z 344DEG 8KT 3585 8121 3570 8138

LANE