Hail and Damaging Winds in North Carolina, May 4, 2019

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
154 PM EDT Sat May 4 2019

.SYNOPSIS...
A weak cold front will approach the region from the west today and
then move east of the area through Sunday. Weak upper-level
disturbances will cross the region on Monday and Tuesday. A
stationary surface front will then become draped just north of the
area on Wednesday. Instability will return south of the stalled
front through late week as another cold front approaches from the
west.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 150 PM EDT Saturday: Main update for the 18Z TAF issuance
along with minor adjustments to temperatures/PoPs to coincide
with latest trends, as the rest of the near term forecast
remains on track. Per latest obs, temperatures are running a few
degrees faster than previously anticipated in a handful of
locations, with upper 70s to lower 80s currently across the
area. Showers and thunderstorms are beginning to move
into/develop across the western portions of the FA, especially
northeast GA and the southern NC mountains. Expect this activity
to continue through this evening as latest mesoanalysis
continues to illustrate plenty of support for thunderstorm
development, with the potential for strong to severe storms.

Otherwise, from the previous discussion...

A well defined shortwave will move thru the lower Mississippi Valley
this morning. This wave helped drive MCS activity overnight. Some
of the DPVA generated by this shortwave, and/or MCVs associated
with that nocturnal convection, will be carried in our direction,
and 250mb winds become increasingly divergent with time today. Warm
and moist sfc conditions, along with modestly favorable mid to upper
level lapse rates, will support diurnal destabilization concurrent
with the improving dynamics. SPC has retained a Slight Risk for
our CWFA on the latest Day 1 outlook. The only question at this
point is how much buoyancy will develop; while some disparity
is seen between guidance members, HREF SBCAPE progs along with
the operational NAM/GFS agree on the Piedmont eventually seeing
values exceed 1000 J/kg. Several sources show a sharp gradient
between the Piedmont and mountains. Shear profiles will improve as a
midlevel jetlet arrives later in the day, which will lengthen mostly
unidirectional hodographs. Accordingly the 00z-cycle CAMs depicted
a linear MCS forming over northern GA and propagating ENE in the
more unstable Piedmont air. The 06z NAMNest and latest HRRR show
the same idea, just delaying a bit w.r.t. the 00z guidance. This
scenario likely would result in swaths of wind damage if it were
to occur (HRRR runs have been producing small areas of 45-50 kt
downdrafts, with county-sized areas of 30-40 kt). The stronger
component storms and/or discrete cells forming away from any
MCS could also be capable of 1 to 2 inch hail. Locally heavy
rain is likely along the leading edge of storm clusters today,
with CAM output suggesting a quick inch of rain could occur with
the strongest cells. The overall storm motion coupled with recent
dry weather in most areas keeps FFG values on the high side and
the overall flash flood threat small, though if small clusters do
develop the unidirectional flow will permit training.

A lull is likely in precip after the afternoon storms run their
course, but precip will return tonight with the passage of a weak
cold front trailing the shortwave and attendant sfc low as it moves
toward the Mid-Atlantic coast. As is often the case, the nature of
the second round is not well agreed upon by the various models,
with varying degrees of moisture and instability depicted in the
wake of the earlier activity. Enough moisture is expected to be
available near the front to retain a mid-range PoP in most areas
throughout the night. Upper forcing will be most significant in the
NW half of the area, and westerly upslope lift will set up later,
and likely to categorical PoPs thus result for the mountains and
foothills. Cloud cover will offset any cooling trend, so mins will
be similar to those this morning. Some low stratus and fog appears
likely to redevelop, with the cold front too weak to really scour
out the moist air, and precip occurring after dark. Confidence is
too low to warrant any Dense Fog Advisory at this point.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 2 am EDT Saturday: Although the upper-level flow pattern
flattens out considerably by Sunday, embedded 500 mb vorticity lobes
will cross the region during peak heating Sunday afternoon to keep
scattered convection going atop the region. Instability will be
greatest southeast of Interstate 85, especially if the passing, weak
surface cold front gets a bit hung up near the extreme southern
Appalachians as the 00Z models are indicating. However, low-level
northwesterly downsloping flow and mid-level drying eventually
working in from the west should keep coverage more on the scattered
side for the bulk of the day. The better instability/shear overlap
for strong to severe thunderstorms should be shunted east of the
forecast area across the coastal plain of the Carolinas by Sunday
afternoon/evening.

The shallow, passing upper trough will move offshore on Monday with
heights beginning to build from the west. The numerical models have
trended toward slightly less boundary layer drying for the early
part of the week, and any return to weak southerly surface to 850 mb
flow could yield isolated showers in the upslope zones in and near
the mountains for Monday afternoon/early evening. Temperatures will
rebound to at least a category above climatology through Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 230 am EDT Saturday: Flat upper ridging will develop atop the
region Tuesday through Tuesday night. A surface cold front will
stall north of the area from the Ohio Valley to the mid-Atlantic
region while offshore surface high pressure permits a return to
southerly flow across the southeast - along with warming
temperatures. Diurnal instability could force some isolated to
scattered showers and thunderstorms Tuesday afternoon/evening,
especially near the Blue Ridge mountain range.

A shortwave will likely lift from east Texas to the central
Appalachians Wednesday into Wednesday night. Forcing ahead of this
feature, along with gradually building instability over the
southeast, will permit an uptick in precipitation chances -
especially over the southern Appalachians. Any precipitation along
and near the stalled front to the north could also allow some
ageostrophic adjustment southward of the boundary in backdoor
fashion, but the latest model runs appear to delay this a bit more
into late week. Wherever the southward progression of the boundary
stops, mid to upper 60s dewpoints are likely to pool in the
associated warm sector and yield considerable afternoon instability.
Meanwhile, deep-layer southwesterly flow will get established
through late week well east of low pressure developing over the
desert southwest. The combination of these features will require
scattered to numerous diurnal shower/thunderstorm chances east of an
approaching cold front Thursday through Friday. Warm sector maxes
will top out well into the 80s, with some upper 80s over the
southern piedmont. The I-40 corridor could be considerably cooler
than forecast depending on the eventual backdoor front evolution.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: VFR prevails across the area this
afternoon, with the exception of KCLT, which is currently marginal
MVFR due to lingering low cigs. Expect these cigs to scatter out
over the next hour. Showers and thunderstorms, some which may become
severe, are expected to affect all terminals through the afternoon
and early evening hours, as latest radar imagery depicts showers and
thunderstorms already developing/moving into the area, up to just
west of the I-77 corridor/KCLT. Low cigs and periods of heavy
rainfall are expected to create periods of flight restrictions, as
noted in going TAF fcst, with gusty winds possible in strong storms.
Though some improvement to VFR is still possible after convection,
confidence is low attm, as a gradual downward trend of flight
restrictions to MVFR/IFR (low cigs/areas of fog) is expected tonight
into the morning hours on Sunday, with another round of showers,
isolated thunderstorms possible overnight. Confidence on fog/stratus
trend for the overnight hours is low attm, given the poor confidence
of the guidance as seen over the past few nights. On Sunday,
improvement to VFR is possible towards the end of the valid TAF
period, but more likely to be marginal MVFR with lingering low cigs,
areas of fog/low vsbys, and VCSH/VCTS. SSW winds throughout today
AOB 10 kts (higher in stronger storms), will gradually veer Sunday
into Sunday afternoon as a weak cold front drops southeastward
through the area.

Outlook: SHRA/TSRA potential will continue through Sunday evening.
Otherwise, expect VFR.

Confidence Table...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       High 100%     High  97%     High  84%     High  92%
KGSP       High 100%     High  99%     High  84%     High  97%
KAVL       High 100%     Med   78%     High  83%     High  91%
KHKY       High 100%     High  91%     Med   79%     High  93%
KGMU       High 100%     High  99%     Med   75%     High  91%
KAND       High 100%     High  99%     High  89%     High  88%

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...HG
NEAR TERM...SGL/Wimberley
SHORT TERM...HG
LONG TERM...HG
AVIATION...SGL

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
356 AM EDT Sat May 4 2019

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-050800-
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-
356 AM EDT Sat May 4 2019

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

.DAY ONE...Today and tonight.

Numerous thunderstorms are expected to impact the area today,
especially along a developing line of storms expected to sweep
northeast through the region this afternoon and evening. Some of
these thunderstorms will likely become severe, with damaging winds
and large hail being the primary threats. The thunderstorms will move
quickly, but briefly heavy rainfall could produce isolated flooding
of low-lying and poor drainage areas. Expect frequent cloud to ground
lightning in the stronger thunderstorms as well. A few thunderstorms
could linger into the overnight hours.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
117 PM EDT Sat May 4 2019

GAZ010-SCZ001-041745-
Rabun GA-Oconee Mountains SC-
117 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL RABUN AND
NORTHWESTERN OCONEE COUNTIES UNTIL 145 PM EDT...

At 117 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Walhalla, or 4 miles southwest of Oconee State
Park, moving northeast at 15 mph.

Locations to be impacted include...
Oconee State Park and Mountain Rest.

Wind gusts up to 45 mph and half inch hail will be possible in these
areas.

LAT...LON 3477 8324 3484 8329 3499 8310 3483 8297
TIME...MOT...LOC 1717Z 237DEG 14KT 3484 8318

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
127 PM EDT Sat May 4 2019

SCZ001-002-041800-
Pickens Mountains SC-Oconee Mountains SC-
127 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN PICKENS AND
NORTHEASTERN OCONEE COUNTIES UNTIL 200 PM EDT...

At 126 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles north of Walhalla, or near Devils Fork State Park, moving
northeast at 25 mph.

Locations to be impacted include...
Devils Fork State Park, Keowee Toxaway State Park, Jocassee Gorges,
Lake Jocassee, Lake Keowee, Nine Times and Bad Creek.

Wind gusts up to 45 mph and half inch hail will be possible in these
areas.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Lakes Jocassee and Keowee are in the path of this storm. Cloud to
ground lightning and gusty winds will create dangerous boating
conditions. Move to shore immediately.

&&

LAT...LON 3505 8291 3508 8282 3492 8282 3489 8307
      3496 8310
TIME...MOT...LOC 1726Z 244DEG 20KT 3495 8300

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
133 PM EDT Sat May 4 2019

NCZ068-069-041800-
Cleveland NC-Lincoln NC-
133 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT WESTERN LINCOLN AND CENTRAL
CLEVELAND COUNTIES UNTIL 200 PM EDT...

At 133 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Shelby, or near Lawndale, moving northeast at 20 mph.

Locations to be impacted include...
Belwood, Lawndale, Fallston, Kingstown and Polkville.

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

LAT...LON 3545 8137 3542 8143 3542 8145 3541 8145
      3534 8156 3538 8164 3556 8149
TIME...MOT...LOC 1733Z 219DEG 17KT 3541 8154

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
138 PM EDT Sat May 4 2019

GAZ028-SCZ010-041815-
Hart GA-Anderson SC-
138 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN HART AND WEST CENTRAL
ANDERSON COUNTIES UNTIL 215 PM EDT...

At 138 PM EDT, Doppler radar was tracking a strong thunderstorm near
Hartwell, moving northeast at 15 mph.

Locations to be impacted include...
Hartwell, Reed Creek, Lake Hartwell, Townville and Sadlers Creek
State Park.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Lake Hartwell is in the path of this storm. Cloud to ground
lightning and gusty winds will create dangerous boating conditions.
Move to shore immediately.

&&

LAT...LON 3431 8299 3438 8306 3453 8294 3458 8288
      3443 8272
TIME...MOT...LOC 1738Z 225DEG 13KT 3438 8297

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
151 PM EDT Sat May 4 2019

NCZ064-065-041815-
Transylvania NC-Henderson NC-
151 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN TRANSYLVANIA AND
NORTHWESTERN HENDERSON COUNTIES UNTIL 215 PM EDT...

At 151 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles north of Brevard, or 4 miles southeast of Mount Pisgah, moving
northeast at 15 mph.

Locations to be impacted include...
Mills River, Looking Glass, Forge Mountain and North Transylvania.

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

LAT...LON 3544 8263 3534 8258 3530 8274 3536 8278
      3545 8265
TIME...MOT...LOC 1751Z 241DEG 12KT 3536 8271

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
153 PM EDT Sat May 4 2019

NCZ068-041830-
Cleveland NC-
153 PM EDT Sat May 4 2019

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL CLEVELAND COUNTY UNTIL
230 PM EDT...

At 153 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles north of Shelby, or 4 miles southeast of Lawndale, moving
northeast at 15 mph.

Locations to be impacted include...
Shelby, Fallston and Waco.

Wind gusts up to 50 mph and dime 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 3542 8146 3536 8141 3534 8137 3530 8157
      3537 8161 3545 8147
TIME...MOT...LOC 1753Z 241DEG 11KT 3536 8152

LANE