Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
126 AM EDT Fri May 7 2021

.SYNOPSIS...
High pressure will continue to lead to mostly dry conditions this
afternoon into this evening, however a few isolated showers cannot
be ruled out across the Upstate. Friday a cold front tracks across
the CWA leading to cooler high temps along with rain showers
possible especially across the NC mtns. This weekend should be
mostly dry due to high pressure to our south gradually tracking east
into the western Atlantic. Mountain showers will remain possible
this weekend despite this area of high pressure. A low pressure
system tracking out of the Southern Plains will increase our rain
chances late Sunday into Monday with thunderstorms possible Monday
afternoon. Tuesday high pressure returns behind the departing cold
front leading to drier conditions and cooler temps.

&&

.NEAR TERM /THROUGH TODAY/...
100 AM Update...No sigfnt changes to the fcst grids. Updated PoPs to
account for isol -shra/tstms across the ern zones thru 06z.

As of 930 PM: Water vapor imagery depicts a broad upper trough
across the eastern half of the CONUS, within which two smaller
shortwaves are embedded. The leading wave is basically a shear axis
over the Carolinas, while a better defined wave is crossing into the
OH and TN Valley upstream. A few showers with a rumble or two of
thunder have developed through orographic lift, ahead of the front
over the South Mountains and Catawba River (NC) and the northern
Upstate of SC. This should slowly propagate ESE over the next few
hours, with the intention of fully dissipating by midnight. There
are already signs of weakening with these showers.

The second wave has produced an MCS type feature, but has rapidly
weakened as it enters a more stable airmass in W TN. Conditions do
not look favorable for it to survive past the TN/NC border. The
shortwave however will reach the CWA overnight, along with a weak
cold front and/or remnant MCS cold pool. Upslope PoPs return to the
TN border areas as a result. It's not absolutely out of the question
that a shower could pop up east of the mountains late tonight, but
there is little support for that from the meso models. Furthermore
prog soundings don't depict much viable instability despite
improving lapse rates aloft. The onset of CAA will induce gusty
winds over the mountains in the predawn hours. Min temps will end up
several degrees below climo over most of the area; the highest
elevations of the mtns look to bottom out just above freezing.
Expecting breezy/cloudy conditions, however, frost looks unlikely. A
few snowflakes could even mix in with rain at high elevations, but
moisture looks too shallow to allow much ice nucleation.

Another day of plentiful cumulus is expected Friday, but as
noted above, meso model depiction of precip is too spotty to warrant
a PoP at this time. Exceptionally deep mixing (750-800 mb top of
PBL) within the post-frontal continental airmass will result in
dewpoints dipping near peak heating, and despite max temps remaining
7-12 degrees below normal, RH looks to go below 30 percent
concurrent with the gusty winds across the NC Piedmont. Fire Danger
Statement being hoisted. Please see Fire Wx section below.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY/...
As of 2:30 PM EDT Thursday: Friday night into Saturday the western
periphery an upper level trough will continue tracking east off the
Mid-Atlantic states while a low pressure system meanders around the
NW CONUS. This trough combined with a dissipating cold front
approaching the Appalachians will keep a slight chance for showers
around in the northern NC mtns. Models have backed off quite a bit
in regards to the coverage of showers in the NC mtns so I updated
the PoPs to reflect this change. This system will also act increase
cloud cover across the entire forecast area. Meanwhile an area of
high pressure will be situated to our south throughout the day
Saturday leading to drier weather. This high pressure system will
gradually be pushed east into the western Atlantic in response to a
low pressure system forming near the Southern Plains while tracking
east Sunday. Most of Sunday should remain dry, however rain chances
will increase from west to east late Sunday as a warm front
associated with the low pressure system tracks into the TN valley.
This front will also increase cloud cover across the CWA late
afternoon/evening Sunday. Below normal low temps can be expected
Friday night due to WNW/NW flow leading to CAA into the area. Highs
on Saturday will remain below normal, but will be warmer compared to
Friday due to flow becoming westerly. Lows Saturday night will be
warmer thanks to WAA from the approaching warm front leading to
SW'ly flow. Highs Sunday will be a few degrees above normal due to
continued SW'ly flow aloft.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 2:30 PM EDT Thursday: The low pressure system is expected to
continue tracking eastward out of the central CONUS Sunday night
into Monday. This system will drag a cold front across the area on
Monday leading to likely categorical PoPs. Rain can be expected
during the morning hours with thunderstorms possible Monday
afternoon/evening as models are hinting at a little bit of
instability available with this FROPA. However, at this time the
severe threat looks to be minimal due to the orientation of the
front. Lows Sunday night should be above normal thanks to good
insolation and WAA. Highs Monday should be near normal. Lows Monday
night will be cool due to flow becoming W'ly and NW'ly.

Tuesday zonal flow will be present across much of the SE CONUS as
high pressure over the Great Lakes extends down into the Mid-
Atlantic leading to drier conditions. The Canadian and GFS are
trending wetter for our area due to the high pressure remaining
further north while the ECMWF is trending drier due to having the
area of high pressure sinking further south. Due to model
disagreement and in collaboration with neighboring WFOs, I have
upped PoPs Tuesday to slight chance to chance.

Wednesday the high pressure system will remain to our north while a
low pressure system is draped across the Gulf Coast. 850 mb flow
will be southerly allowing for increased cloud cover and moisture
for our area Tuesday night into Wednesday. This high to our north
combined with E'ly and NE'ly flow at the sfc could allow for hybrid
CAD to develop leading to well below average high temps. This setup
should allow rain chances to return into the forecast. Thursday both
the GFS and ECMWF have rain chances sticking around due to the low
pressure system tracking off the SE coast ending up offshore of the
Carolinas. The Canadian has a faster solution with this system, so
for the time being I have decided to maintain PoPs for the end of
the forecast period. Thunderstorm chances look to remain low at this
time Wednesday and Thursday due to the fact that we will likely have
CAD in place.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: An upper level trof crossing the area will
generate a few brief -shra and possibly some thunder this morning
possibly at KAVL and east toward KCLT. Otherwise, VFR conds and
expect the atmos to remain mixed overnight. Deeper mixing will
develop by mid-morning and nw/ly gusts are likely in the 20-25 kt
range thru the afternoon before tapering off arnd 00z, except at KAVL
where low-end to moderate gusts will continue thru the period.

Outlook: Predominately VFR conditions are expected thru the
weekend. The next system to bring restrictions is looking like it
will arrive on Monday of next week.

Confidence Table...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       High 100%     High 100%     High 100%     High 100%
KGSP       High 100%     High 100%     High 100%     High 100%
KAVL       High 100%     High  95%     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 are available at
the following link:

www.weather.gov/gsp/aviation

&&

.FIRE WEATHER...
The good lapse rates underneath passing shortwave trough will allow
very good mixing on Friday afternoon, which suggests dewpoints will
potentially drop more than model guidance would suggest. Modest
flow in the midlevels will be brought down to the surface as gusts
near if not above 25 mph. While fuels remain moist following recent
heavy rains, the meteorological conditions are marginally conducive
to elevated fire danger; fuels dry quickly in these conditions
anyway. Thus, in coordination with NCFS, we are issuing a Fire
Danger Statement for the NC Piedmont for Friday afternoon.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Fire Danger Statement from noon EDT today through this evening
     for NCZ035>037-056-057-068>072-082-501>510.
SC...None.

&&

SYNOPSIS...AP
NEAR TERM...CAC/SBK/Wimberley
SHORT TERM...AP
LONG TERM...AP
AVIATION...SBK
FIRE WEATHER...GSP

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
415 PM EDT Thu May 6 2021

GAZ010-017-018-026-028-029-NCZ033-048>053-058-059-062>065-SCZ001>014-
019-072015-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Avery-Madison-Yancey-
Mitchell-Swain-Haywood-Buncombe-Graham-Northern Jackson-Macon-
Southern Jackson-Transylvania-Henderson-Oconee Mountains-
Pickens Mountains-Greenville Mountains-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
415 PM EDT Thu May 6 2021

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

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ035>037-056-057-068>072-082-501>510-072015-
Alexander-Iredell-Davie-Catawba-Rowan-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-
415 PM EDT Thu May 6 2021

...FIRE DANGER STATEMENT IN EFFECT FROM FRIDAY AFTERNOON THROUGH
FRIDAY EVENING...

This Hazardous Weather Outlook is for piedmont North Carolina and
western North Carolina.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

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

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Fire Danger Statement.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
208 AM EDT Fri May 7 2021

NCZ071-072-070645-
Cabarrus NC-Mecklenburg NC-
208 AM EDT Fri May 7 2021

...A THUNDERSTORM WITH SMALL HAIL WILL IMPACT CABARRUS AND EAST
CENTRAL MECKLENBURG COUNTIES UNTIL 245 AM EDT...

At 207 AM EDT, Doppler radar was tracking a thunderstorm 8 miles
southwest of Downtown Concord, or near University City, moving east
at 20 mph.

Locations to be impacted include...
Downtown Concord, Kannapolis, Northeast Charlotte, East Charlotte,
West Concord, Harrisburg, Mt Pleasant, University City, Reedy Creek
Park and Charlotte Motor Speedway.

Pea size hail and occasional lightning will be possible in these
areas.

LAT...LON 3524 8046 3520 8076 3537 8082 3551 8047
      3550 8046 3535 8040
TIME...MOT...LOC 0607Z 252DEG 18KT 3532 8071

HG