Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1046 AM EDT Wed Jun 30 2021

.SYNOPSIS...
High pressure off the Atlantic coast weakens as a cold front drops
into the area by Friday. Increasing moisture between the high and
cold front will allow showers and thunderstorms to develop each day
with increasing coverage through Friday night. The front moves east
of the area by Saturday and Independence Day. Near seasonal
conditions expected early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1030 am: An upper level ridge axis will remain centered across
the FA today and maintain weak flow thru the column. A combination
of high surface dewpoints and strong insolation is already yielding
moderate instability (i.e., sbCAPE > 2000 J/kg) across the Piedmont,
and a cu field is steadily expanding in area and height across our
southern tier of zones. Some of the 00Z CAMs allowed isolated to
scattered convection to develop in this general vicinity early this
afternoon before fizzling during mid/late afternoon. This is not
uncommon during summer mornings/early afternoons with good
instability before deeper mixing lowers instability and raises LFCs
during mid/late afternoon. In terms of the official forecast, we
have backed up slight chance PoPs across southern areas to as early
as noon. Otherwise, we are still expecting the best coverage across
the mountains during mid/late afternoon. Considering the level of
instability, can't rule out a brief strong-to-marginally severe
pulse storm. Slow cell movement will also yield locally heavy
rainfall. All activity will be diurnally driven and wane during the
late evening and overnight. With little change in the pattern and
high sfc-layer RH, expect patchy to areas of dense morning fog
across the mtn valleys once again. Typical summertime temps and
humidity along with weak sfc winds will persist thru period.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 230 AM EDT Wednesday: Guidance continues to be in good
agreement during this period. An upper low steadily drops south
across the Great Lakes Thursday then into the Mid-Atlantic on
Friday. The associated deep upper trough drops into the OH River
valley Thursday and into our area Friday. An associated surface
front drops toward the area Thursday and into the area Friday. There
is plenty of moisture associated with this system as PW values
rising into the 2 inch range across the area. Given the forcing and
moisture, expect widespread convection across the area producing an
excessive rainfall threat, mainly across the mountains on Thursday
and all areas Friday. Instability will be better on Thursday, along
with some DCAPE. Shear will be better on Friday but instability will
be limited. There will be a low end strong or severe storm chance
both days, but heavy rainfall is a greater threat. Precip chances
taper off Friday night as the front moves through the area and drier
air filters in.

Hot and humid conditions continue to Thursday but highs fall below
normal for Friday. Lows will be near or slightly above normal
Thursday night then below normal Friday night.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 310 AM EDT Wednesday: Guidance continues to show good
agreement with the system moving out of the area from the short
range. The upper low and main part of the upper trough move east of
the area through the weekend. Saturday looks mostly dry, but will
hold onto a slight chance south of I-85 where moisture could linger
if the associated cold front stalls slightly. Independence Day now
looks dry with high pressure moving in behind the departing front.
Monday is looking dry as well with high pressure remaining in place.
The high weakens Tuesday with some moisture return beginning across
the area. Therefore, do have PoP rising back to chance west and
slight chance east.

A warming trend develops for the weekend into next week, but highs
remain below normal for the weekend then back to near or a little
above normal Monday and Tuesday. Humidity levels remain in check
despite the increasing moisture keeping heat index values near the
actual temps.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Dense VLIFR fog will linger at KAVL this
morning and begin to dissipate arnd 13z. All other TAF sites should
remain VFR early and thru the afternoon, with some VSBY issues
possible at KAND arnd daybreak. The best chance for tstms will be
across the NC mtns and have included a PROB30 for TSRA at KAVL
covering the later afternoon. KAND could also see isol showers
and/or thunder near the terminal this afternoon and have a VCSH thru
00z. Winds will remain rather weak and favor a s/ly to sw/ly
direction as a weak sfc trof is maintained across the region.

Outlook: A cold front is expected to bring periods of numerous to
widespread convective coverage to the area from late Thu through
early Saturday. Fog and low stratus will be possible each morning as
well, primarily in the mountain valleys.

Confidence Table...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High  98%     High 100%     High  93%     Med   75%
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 are available at
the following link:

www.weather.gov/gsp/aviation

&&

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

&&

SYNOPSIS...RWH
NEAR TERM...JDL/SBK
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...SBK

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
420 AM EDT Wed Jun 30 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-010830-
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 NC-
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-Union SC-Chester-Greenwood-
420 AM EDT Wed Jun 30 2021

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

.DAY ONE...Today and tonight.

Scattered thunderstorms, mainly across the mountains, are expected
this afternoon and early evening. Cloud-to-ground lightning and
brief, heavy rainfall are the main threats.

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

Showers and thunderstorms are expected to increase in coverage ahead
of a cold front Thursday and remain over the area Friday and Friday
night as the front slowly crosses the area. Areas of heavy rainfall
will be possible, potentially leading to isolated flash flooding.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
151 PM EDT Wed Jun 30 2021

NCZ072-301815-
Cabarrus NC-
151 PM EDT Wed Jun 30 2021

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL CABARRUS COUNTY UNTIL
215 PM EDT...

At 151 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles southeast of Downtown Concord, moving southwest at 10 mph.

Locations to be impacted include...
Downtown Concord, Harrisburg, Charlotte Motor Speedway, Midland, West
Concord and Mt Pleasant.

Wind gusts up to 35 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 3527 8045 3519 8051 3527 8067 3534 8069
      3536 8072 3546 8055 3535 8040
TIME...MOT...LOC 1751Z 043DEG 10KT 3535 8054

ARK