Hail and Damaging Winds in North Carolina, May 10, 2018

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1052 AM EDT Thu May 10 2018

.SYNOPSIS...
Shower and thunderstorm chances will increase across the area
Thursday as a front approaches. Isolated to scattered mountain
and foothill showers/t- storms are expected Friday through Sunday
as temperatures increase to well-above normal across the area.
Hot Piedmont temperatures continue through Monday before increasing
cloud cover and precip chances gradually reduce max temperatures to
slightly above-normal by next Wednesday as a complex low pressure
system impacts the area.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1035 AM: Visible satellite imagery shows cloudiness mainly
across the TN border area of the western NC mountains, with much
better heating occurring in areas east of the mountains. Surface-
based CAPE values on the latest LAPS analysis are already revealing
some 1000+ J/kg over the upper Savannah River area with 500 to 700
J/kg along the I-40 corridor. The region thus appears well on the
way to some 2000+ values east of the mountains during peak heating.
Meanwhile, water vapor imagery shows a shortwave moving southeast of
the OH valley and convection should trigger rapidly over and near
the southern Appalachians ahead of this feature and associated
surface front starting circa 18Z. The latest convection-allowing
models have two main clusters/bands of convection forming, with the
more robust area likely moving from the NC foothills across the I-77
piedmont areas through late afternoon before moving east early this
evening. The second band will arrive in the southwest NC mountains
from eastern TN this afternoon but then likely weaken moving across
northeast GA and the western Upstate. Profiles will support a
wind/hail threat with any of this coverage, but the very best
overlap of sfc to mid-level delta theta e values, surface DCAPE, and
strengthening cool pool outflows could be across the Charlotte metro
area and the surrounding piedmont from 4 to 6 pm. The westerly shear
appears a bit too modest for much of a tornado threat at present.

The thunderstorm activity should move off to our east around sunset.
Thereafter, the weakening sfc cold front will move east and we
should be fair for the overnight hours, with perhaps some locally
dense fog where any heavier rain falls today. Min temps will be
about five degrees above normal in spite of the front having passed.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 330 AM EDT Thursday: Mid-level flow will be predominately
zonal (flat) on Friday, with a broad weakness centered over the
western GoMex embedded in the building subtropical ridge stretching
from Texas to the western Atlantic.  The weakness and developing
closed low will monopolize our pattern heading into next week,
but for Friday, a weak perturbation in the zonal flow will move
across the area during peak heating to give a modest boost to
mountain and foothill shower and general thunderstorm chances.
Perhaps the bigger story will be high temperatures, which should
reach 90 along and S of I-85 as the subtropical ridge builds north
into our area and a low-level westerly flow introduces a modest
downslope component to the warming trend.  As appropriately noted
yesterday, the average first date of 90-degree weather is May 20
for CLT and May 24 for GSP, so while this is early, it's certainly
nowhere near the earliest on record.

A slightly stronger shortwave dives into the upper TN valley
overnight Friday and a weak mid-level trough/vorticity axis slowly
crosses the area for Saturday.  This will be reflected into the
lower-levels and at the surface by a trough axis with winds out of
the SW ahead of the trough veering to westerly Saturday evening.
This feature will enhance shower and storm chances across the
mountains Saturday afternoon with slightly better chances for
some of this convection to "break containment" and cross the Blue
Ridge into the NW NC Piedmont.  While low-level lapse rates will be
steep given the further airmass heating and SBCAPE values should
be in the 1000-1500 J/kg range, some mid-level warming may reduce
overall instability.  Either way, any thunderstorms that develop
are not expected to be significantly strong and, once again, the
main story will be high temperatures, tweaked just a degree higher
(what's another degree?) across the area with 90-92 widespread
across the Piedmont.  These temperatures will not be hot enough
to threaten records.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 330 AM EDT Thursday: The overall expectations for the extended
have changed little, but there will assuredly be many adjustments
to the details for next week as the pattern will be rather complex
which means guidance will struggle.  Sunday will be the peak of
this pre-summer heat wave for our area as the subtropical ridge
reaches 588dm over the Mid-South.  The one thing going for us will
be the dewpoint/humidity values, which will stay in the 60-62 range
outside of the mountains, so heat indices will not be a concern.
Nevertheless, as mentioned by the previous shift, it will still be
important to take it easy outdoors.  As done on Saturday, guidance
has nudged max temperatures another degree or so higher on Sunday
and now we are flirting with record temperatures outside of the
mountains, especially for the Charlotte area.  See the Climate
section for details.  Low temperatures will not be outdone either
and will also be 8-12 degrees above normal through most of the
extended.

On Sunday, precip chances could not be entirely eliminated for
the ridge tops, but SBCAPE values over the mountains will be less
than 1000 J/kg. and with the mid-level ridge axis overhead, shear
will be minimal and the corresponding mid-level warm layer should
provide some inhibition.

Monday has gradually trended warmer over the past several forecast
cycles as the previously advertised frontal boundary is unlikely
to reach our area at all given the dominant ridge in place.
Highs will remain in the lower 90s with dewpoints in the lower 60s,
but should fall just short of records at GSP and CLT.  In any case,
the forecast becomes more complex as the previously mentioned
weakness in the western Gulf migrates east over the weekend and
consensus has it becoming a closed low that slowly moves north
Monday through Wednesday in response to height falls over the
Plains.  The presence and position of the closed low relative to
our area will likely place the region in moist southerly flow for an
extended period next week.  This will mean a rather unsettled week
is in store with precip chances persisting both day and night in
the proximity to a possible surface closed low reflection of the
upper low moving into the Southeast by mid-week.  The good news
is that the suppression of the ridge and increased cloud cover and
moisture will work to reduce high temperatures back to near normal
Tuesday and Wednesday, but it will be more humid with dewpoints
rising into the mid- and upper 60s east of the mountains due to the
increasing and persistent moisture flux from the Gulf and Atlantic.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
At KCLT and Elsewhere: VFR conditions will continue as convective
cumulus develops across the region 16Z to 18Z with heating.
Anticipate gusts steadily increasing in the SW flow as mixing
develops. Convection should form just east of the Blue Ridge this
afternoon and make a run from mainly near KHKY across the KCLT
region through late afternoon or very early evening. A second band
of convection is likely across the southern Appalachians but with
more questionable coverage from KAVL across the Upstate sites. With
the front coming in from the WNW, expect the typical GSP mountain
split with some activity going across NC and other activity diving
down into GA. Thus, the upstate TAFs get only a VCTS, while the NC
sites get a 3 to 4 hour window of TEMPO containing an MVFR
restriction for thunderstorms and some gusts. The storms should exit
quickly by 23Z or so based on the CAM guidance, with some potential
for lingering light precip, and thereafter just convective debris
and a WNW wind. There is some indication of fog, perhaps an IFR
restriction, across the KCLT area in the pre-dawn hours on Friday.

Outlook: Isolated to scattered diurnal convection will likely return
mainly over the higher terrain on Friday and into the weekend. Any
restrictions should be confined to areas under showers/thunderstorms
or daybreak fog/stratus in the lower mountain valleys.

Confidence Table...

            15-21Z        21-03Z        03-09Z        09-12Z
KCLT       High 100%     High 100%     High 100%     High  88%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High 100%     High 100%     High  94%
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

&&

.CLIMATE...
RECORDS FOR 05-10

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      89 1936     53 1924     65 1927     32 1966
                1896                                1906
   KCLT      94 1896     59 1966     70 1927     38 1906
                1889
   KGSP      96 1889     56 1924     71 1895     32 1906

RECORDS FOR 05-11

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      89 1889     50 1960     64 1890     30 1966
   KCLT      95 1916     58 1924     70 1889     39 1977
                1896
                1889
   KGSP      96 1889     59 1924     69 1963     33 1906

RECORDS FOR 05-12

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      88 1980     44 1960     65 1918     36 1969
                1956
                1914
   KCLT      94 1889     56 1960     69 1896     39 1969
   KGSP      99 1916     56 1960     68 1979     38 1989
                                        1933
RECORDS FOR 05-13

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      90 1933     54 1917     67 1890     31 1895
   KCLT      93 1881     59 1891     73 1881     38 1960
   KGSP      95 1886     62 1972     71 1933     37 1917
                            1954
                            1938

RECORDS FOR 05-14

               MAX TEMPERATURE         MIN TEMPERATURE
  STATION      HIGH        LOW         HIGH        LOW
  -------  ----------  ----------  ----------  ----------
   KAVL      89 1956     52 1954     63 1962     30 1895
                1896                    1908
   KCLT      95 1956     53 1954     73 1881     41 2013
                                                    1917
   KGSP      95 1886     52 1954     71 1933     41 2013
                                                    1960
                                                    1917

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

SYNOPSIS...JMP
NEAR TERM...HG/PM
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...HG/PM
CLIMATE...JMP/HG

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
1107 AM EDT Thu May 10 2018

GAZ010-017-018-NCZ033-035>037-048>053-056>059-062>065-068>072-082-
501>510-SCZ001>009-013-014-111515-
Rabun-Habersham-Stephens-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-Chester-
1107 AM EDT Thu May 10 2018

This Hazardous Weather Outlook is for the northeast Georgia
mountains, western North Carolina, and the northern Upstate of
South Carolina.

.DAY ONE...This Afternoon and Tonight.

Scattered to numerous thunderstorms are expected to develop ahead of
a cold front approaching from the west this afternoon. These storms
are expected to strengthen over the mountains this afternoon, with
some of the thunderstorms becoming severe over the foothills and
especially the piedmont late this afternoon through early this
evening. Cloud-to-ground lighting, briefly heavy rainfall, and gusty
winds can be expected with any of these storms. Some of the strongest
thunderstorms will be capable of producing quarter-sized hail and
damaging wind gusts. The storms should move away to the east by
around sunset.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

..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.
..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.

.SPOTTER INFORMATION STATEMENT...

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

GAZ026-028-029-SCZ010>012-019-111515-
Franklin-Hart-Elbert-Anderson-Abbeville-Laurens-Greenwood-
1107 AM EDT Thu May 10 2018

This Hazardous Weather Outlook is for the northeast Georgia piedmont
and the southern part of Upstate South Carolina.

.DAY ONE...This Afternoon and Tonight.

Scattered thunderstorms are expected to develop ahead of a cold
front approaching from the west this afternoon. Cloud-to-ground
lighting, briefly heavy rainfall, and gusty winds can be expected
with any of these storms. One or two of the thunderstorms may become
strong enough to produce large hail and damaging wind gusts. The
storms should move away to the east by around sunset.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

..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.
..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.

.SPOTTER INFORMATION STATEMENT...

Skywarn 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
133 PM EDT THU MAY 10 2018

NCZ504-506-101800-
Greater Burke NC-Eastern McDowell NC-
133 PM EDT THU MAY 10 2018

...A STRONG THUNDERSTORM WILL IMPACT EAST CENTRAL MCDOWELL AND
SOUTHERN BURKE COUNTIES UNTIL 200 PM EDT...

At 133 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles west of Morganton, or near Lake James State Park, moving east
at 25 mph.

Locations to be impacted include...
Morganton, Valdese, Drexel, Connelly Springs, Rutherford College,
Glen Alpine, Lake James State Park, Lake Rhodhiss, South Mountains
State Park and Lake James.

Wind gusts up to 50 mph and half inch 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 3580 8158 3578 8155 3578 8149 3559 8152
      3557 8153 3556 8157 3557 8160 3556 8166
      3558 8169 3558 8170 3561 8172 3561 8176
      3559 8177 3559 8179 3563 8195 3578 8193
      3581 8187
TIME...MOT...LOC 1733Z 279DEG 22KT 3572 8185

Carroll

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
137 PM EDT THU MAY 10 2018

GAZ010-017-018-SCZ001-004-101800-
Rabun GA-Stephens GA-Habersham GA-Greater Oconee SC-
Oconee Mountains SC-
137 PM EDT THU MAY 10 2018

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL STEPHENS...CENTRAL
HABERSHAM...SOUTHERN RABUN AND SOUTHWESTERN OCONEE COUNTIES UNTIL 200
PM EDT...

At 137 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles south of Clayton, or near Lakemont, moving east at 25 mph.

Locations to be impacted include...
Toccoa, Walhalla, Clayton, Clarkesville, Westminster, Tiger, Tallulah
Falls, Lake Rabun, Lake Burton and Lakemont.

Wind gusts up to 50 mph and half inch 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 3489 8353 3488 8302 3451 8313 3452 8315
      3463 8364 3463 8365 3464 8365
TIME...MOT...LOC 1737Z 279DEG 23KT 3477 8341

Carroll

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
158 PM EDT THU MAY 10 2018

NCZ056-502-504-101830-
Greater Burke NC-Greater Caldwell NC-Catawba NC-
158 PM EDT THU MAY 10 2018

...A STRONG THUNDERSTORM WITH INTENSE LIGHTNING WILL IMPACT
SOUTHWESTERN CATAWBA...SOUTHEASTERN CALDWELL AND SOUTHEASTERN BURKE
COUNTIES UNTIL 230 PM EDT...

At 157 PM EDT, Doppler radar was tracking a strong thunderstorm with
intense lightning 4 miles southeast of Morganton, moving east at 25
mph.

Locations to be impacted include...
Morganton, Longview, Sawmills, Granite Falls, Valdese, Icard, Drexel,
Hildebran, Connelly Springs and Rutherford College.

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

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 3586 8137 3556 8140 3556 8142 3566 8183
      3580 8179
TIME...MOT...LOC 1757Z 281DEG 22KT 3569 8166

Carroll