Hail and Damaging Winds in North Carolina, August 21, 2019

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1006 AM EDT Wed Aug 21 2019

.SYNOPSIS...
Expect a return to more typical late summer heat and humidity today
through Friday as a cold front slowly approaches the area from the
northwest. The front will push into the region late Friday through
Saturday, then gradually settle just to our south Sunday into early
next week. An area of high pressure will build in from the north and
maintain cooler than normal temperatures and lingering moisture
behind the front.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EDT Wednesday: Minor adjustments made to
temperatures/sky/PoP to coincide with latest trends, as the rest of
the near term forecast remains on track. Aside from a few light
showers along the TN border, conditions remain dry across the area
this morning, with clouds continuing to burn off across the Upstate
and NW Piedmont. Otherwise, it's humid, with dewpoints in the lower
70s, and current temperatures in the mid to upper 70s/lower 80s.

Previous discussion: As a ridge continues to build over the Southern
Plains, a weak 500 mb vort lobe will cross the area during the peak
heating hours. The energy may help trigger convection in the usual
high terrain points by early aftn. low to mid-lvl flow will shift
from SWLY to WNWLY, steering convection toward the Piedmont late
aftn into early evening. Also, a weak lee trough will set up and may
enhance some convergence along the I-85 corridor. With all that
said, guidance is showing just modest sbCAPE and DCAPE potential. It
looks like severe threat from these storms will be slightly higher
than yesterday, but not as high as Monday. With some mid-lvl dry
air, PWATs come down a bit (mainly 1.5-1.9"). The morning will start
out with areas of fog and stratus, but should mix out to partly
cloudy skies. So a rebound in temps back into the upper 80s to lower
90s is expected east of the mountains.

Tonight...A northern stream trough will begin to dig across the
Upper Midwest, allowing a cold front to push into the Ohio Valley.
Convection is expected to be ongoing across the Ohio Valley thru the
evening hours, but should weaken/fizzle out as it approaches the
southern Appalachians. There will be enough elevated cape and a
light WNW flow that could trigger a few showers along the TN border
due to some upslope forcing. The rest of the area should be dry
overnight with patchy fog and stratus developing once again. Lows
will be a category or two above normal.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 315 am EDT Wednesday: Heights will fall sharply across the
Great Lakes on Thursday, but the associated northern CONUS surface
cold front will make only limited progress southward toward our
forecast area. In the moist and unstable airmass along and near the
southern Appalachians well south of the boundary, afternoon
convective triggering is once again likely along the Blue Ridge
mountain escarpment early Thursday afternoon. This activity should
run east across the piedmont in the westerly steering flow through
late day to warrant solid likely PoPs west to solid chance east.
Temperatures will remain above climo.

Moisture will deepen as the frontal boundary slowly settles
southward toward the forecast area on Friday. The front may stay
just north of western NC through late day, permitting an unstable
warm sector to stay in place most of the day. With sbCAPE values
running 2500 J/kg and precipitable water values closing in on two
inches, can probably introduce some heavy rain wording into the HWO.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 320 am EDT Wednesday: A surface cold front is expected to
settle southward through the forecast area on Saturday. Upper-level
confluence over the northeast will aid cold air damming development
east of the Appalachians over the weekend, especially with another
round of height falls developing from the mid-MS River toward the
Appalachians. This will enhance upglide to help establish the CAD
layer on Saturday and then maintain it Sunday, and beyond, as the
wedge front settles south of the area. Anticipate the heart of the
cold air damming conditions to be in place on Sunday, with maximum
temperatures struggling in the 70s east of the mountains. A heavy
rainfall threat could well remain in place as high precipitable
water air persists in profiles, but instability and associated
precipitation rates will be more of a question mark. Will hold off
on any weekend additions to the HWO.

The upstream trough will cross the southeast early next week to
finally provide some measure of erosion of the surface wedge layer,
with gradual shallowing on Monday and then scouring on Tuesday. Will
keep well above climo PoPs going and permit temperatures to slowly
rebound to a little closer to normal by Tuesday afternoon.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: A weak mid-lvl low continues to slowly drift
NEWD thru the area, producing slow-moving shwrs and tstms that are
shifting east of CLT. The rest of the TAF sites are expected to be
dry overnight. With all the rain that fell yesterday, and a light
WAA SWLY flow in the low-levels, there should be areas of stratus
developing across much of the piedmont and valley fog/stratus in the
mountain valleys. Most of the stratus looks to be over the NC
foothills and piedmont, affecting KHKY and KCLT. The Upstate sites
are less certain, and will be depicted by tempos for now. Conditions
should improve fairly quickly after daybreak today, as flow turns
out of the W/NW and scours out some of the moisture. Convection is
expected to develop with peak heating across the high terrain first,
then generally expand/drift east into the Piedmont late aftn into
the evening. All sites will carry PROB30 for TSRA. Winds will be
light out of the S/SW overnight, increasing slightly out of the SW
this aftn.

Outlook: SHRA/TSRA chances will increase with a cold front
Thursday and Friday, remaining elevated thru the weekend as the
front stalls over the area. Some morning fog and low stratus will be
possible each day, especially in the mountain valleys.

Confidence Table...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       High  93%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     Med   71%
KHKY       High 100%     High 100%     High 100%     High 100%
KGMU       High  98%     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...ARK/HG
NEAR TERM...ARK/SGL
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK

Hazardous Weather Outlook...CORRECTED
National Weather Service Greenville-Spartanburg SC
425 AM EDT Wed Aug 21 2019

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-220830-
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-
425 AM EDT Wed Aug 21 2019

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 afternoon and evening thunderstorms will
develop today. Any of these thunderstorms will have the potential to
produce cloud-to-ground lightning strikes, locally heavy rainfall,
and gusty winds. A few thunderstorms could become severe, with
damaging wind gusts or hail approaching quarter size.

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

Abundant moisture will set up over the region just ahead of a cold
front approaching from the north on Friday. Instability in the
warm and moist air ahead of the front may contribute to locally
excessive rainfall, mainly during the afternoon and evening hours
on Friday. Flooding of low-lying and poor drainage areas will be
possible at any location affected by repeating showers and
thunderstorms, and small streams could approach bankfull where
heavy rain falls.

.SPOTTER INFORMATION STATEMENT...

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
135 PM EDT Wed Aug 21 2019

NCZ065-211800-
Henderson NC-
135 PM EDT Wed Aug 21 2019

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL HENDERSON COUNTY UNTIL
200 PM EDT...

At 134 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles west of Hendersonville, or near Etowah, moving east at 10 mph.

Locations to be impacted include...
Hendersonville, Mills River, Fletcher, Flat Rock, Etowah, Mountain
Home, Laurel Park, Asheville Airport, B.R. Parkway-Mount Pisgah To
The Nc Arboretum and Valley Hill.

Wind gusts up to 40 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 3545 8264 3543 8257 3544 8255 3542 8254
      3543 8253 3544 8254 3544 8249 3526 8241
      3523 8260 3526 8260 3526 8262 3529 8261
      3529 8262 3530 8262 3535 8267 3544 8272
      3545 8271
TIME...MOT...LOC 1734Z 284DEG 9KT 3533 8256

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
150 PM EDT Wed Aug 21 2019

NCZ053-211815-
Buncombe NC-
150 PM EDT Wed Aug 21 2019

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN BUNCOMBE COUNTY
UNTIL 215 PM EDT...

At 150 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles southeast of Downtown Asheville, or near Fairview In Buncombe
County, moving east at 20 mph.

Locations to be impacted include...
Arden, Black Mountain, Swannanoa, Fairview In Buncombe County,
Biltmore Forest, Skyland, B.R. Parkway-Nc Arboretum To East
Asheville, East Asheville and Montreat.

Wind gusts up to 40 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 3562 8227 3561 8228 3559 8229 3556 8225
      3553 8217 3552 8223 3550 8222 3546 8225
      3550 8233 3548 8237 3546 8237 3547 8242
      3545 8247 3545 8252 3555 8256 3565 8228
TIME...MOT...LOC 1750Z 255DEG 18KT 3549 8245