Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
307 PM EDT Thu Mar 18 2021

.SYNOPSIS...
A potent low pressure system will continue to lead to showers
and thunderstorms this afternoon with a few strong to severe storms
possible. The associated cold front should track through the
forecast area during the afternoon hours. Friday the low pressure
system tracks off the East Coast into the western Atlantic. Strong
Canadian high pressure will build into the region behind the
departing low pressure system. This high pressure system will remain
over the eastern CONUS this weekend into the middle of next week
leading to drier weather.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 251 PM: A line of showers and thunderstorms continues to
evolve across Upstate SC and wrn NC. The old wedge boundary has
lifted north of I-85 out ahead of the line, as was indicated by the
model guidance, and many breaks in the clouds ahead of the line in
the Upstate has allowed for boundary layer heating and sfc-based
CAPE upwards of 1000 J/kg across much of the Upstate and reaching
up to I-85, and a max of 1500 J/kg over the lower Piedmont. Shear
was fairly impressive as well...with effective bulk shear above 50kt
where the CAPE plume was located. This environment should continue
to slowly lift northward to encompass much of the Charlotte metro
area through the mid- to late-afternoon. The concern is that as
our line continues to grow, it will break up into a collection of
discrete supercells, given the amount of shear and buoyancy in the
environment out ahead of it. A Tornado Watch has been issued for
the northern Upstate and southern Piedmont of NC, so expect the
situation to become more dynamic and active through late afternoon
as the storms move east.

The convective threat should end gradually from the west as the
afternoon progresses, with the line excelerating a bit and exiting
the fcst area in the early part of the evening. Temps will remain
tricky, with some places in the usual spots of the nrn foothills
not making it out of the 50s while the lower Piedmont and Upstate
makes it well into the 70s. Partial clearing will work its way
in from the west behind the line as the dry slot passes overheaf,
but not early enough to allow temps to rebound.

For tonight, the upper low over middle TN will roll gradually
east over the mtns and then off to the east of the mtns in the
early morning hours on Friday. The upper low will bring a return
of the low cloudiness across the mtns and a resurgence of low
level moisture. The combination of moisture, mid/upper forcing,
and developing upslope flow should be able to produce light precip
over the mtns, maximizing along the TN border. Cold air aloft
associated with the upper low will be sufficient to allow for some
changeover to snow at the very highest elevations, with maybe an
inch of accumulation possible above 5k feet. Wraparound precip
as the upper low passes early Friday will bring a chance of light
rain across the I-40 corridor and down into the nrn part of metro
Charlotte, but that should move out in the morning. Light precip
chances will linger over the higher terrain into Friday afternoon
owing to the cold air aloft. Temps will return toward normal.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 2pm EDT Thursday:  By Friday evening, upper trough will have
settled over the southeast CONUS, with a large area of surface high
pressure to the north.  Upper trough will gradually move
southeastward Saturday and Sunday, being replaced by a ridge west of
the area Sunday evening. Fairly strong surface high to the north
edges slowly eastward over the weekend as well, and will keep brisk
10 to 15 kt northeasterly winds in the forecast through the weekend.
Advection pattern will reinforce cool to cold air, with lows
Saturday and Sunday morning about 10 degrees below normal with frost
or freeze possible.  Highs Saturday also look to be 10 degrees below
normal, but temperatures begin to recover a bit on Sunday which has
highs about 5 degrees above those expected on Saturday.

Models indicate a few showers related to small upper shortwaves, but
Saturday and Sunday will be mostly precipitation-free, with few
clouds.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 230 PM Thursday: Models have a coastal low developing off the
East Coast Sunday night into Monday. However, models are not in
agreement on exactly where this low will form. The ECMWF has the low
forming off the Carolinas while the Canadian and GFS have the low
forming further north off the Mid-Atlantic Coast. Regardless of
where this low forms, models are in good agreement that the strong
area of Canadian high pressure will keep rain chances confined well
to the east and south of the forecast area. The ECMWF is more
aggressive in regards to pushing the moisture associated with this
coastal low further inland compared to other global models. However,
at this time we will keep pops out of forecast as we look to remain
dry into early next week as heights build over the region. Pops
return into the forecast late Tuesday night into Thursday as a cold
front approaches the region from the west. Models are not in sync in
regards to the amount of moisture this FROPA will bring middle to
late next week. Both the GFS and ECMWF have the front tracking
through middle of next week. The GFS has an area of low pressure
developing along the frontal boundary near the central Gulf Coast.
This scenario would keep rain chances around into late next week.
The ECMWF shows more of a a moisture starved FROPA moving through
middle of next week with no area low pressure developing along the
southern frontal boundary. High temps will be near normal Monday and
Tuesday becoming slightly above normal Wednesday and Thursday.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Watching a line of showers and thunderstorms
slowly organize across the NC Foothills and Upstate SC. Out ahead
of the line, low clouds were gradually lifting/scattering from LIFR
to IFR and MVFR. A quick progression is expected in places that are
not already MVFR, with wind coming around to S and becoming gusty
as this happens. The TAFs along and to the east of the line will
handle its passage with a TEMPO for IFR conditions. In general, it
should be to our east by 22Z. Behind the line, a quick improvement
to VFR was noted with a wind shift to SW, and that was included
at all sites. Gusty winds will continue into the evening hours
before weaking and coming around to the NW. We might see temporary
clearing, but cold air aloft will bring another round of mainly VFR
level clouds this evening, dropping to MVFR across the mtns. This
MVFR deck may move east across the nrn foothills and wrn Piedmont,
impacting KHKY and KCLT beginning before the start of operations
and continuing well into Friday. Wind should become gusty from
the NE on Friday morning.

Outlook: Conditions will become VFR Friday night and remain that
way into early next week.

Confidence Table...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       High  85%     High 100%     High 100%     High  93%
KGSP       High  92%     High 100%     High 100%     High  95%
KAVL       High  94%     High  82%     Med   77%     High  95%
KHKY       High  83%     High  97%     High 100%     High  87%
KGMU       High  91%     High 100%     High 100%     High  96%
KAND       High  95%     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...AP
NEAR TERM...PM
SHORT TERM...WJM
LONG TERM...AP
AVIATION...RWH

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
448 AM EDT Thu Mar 18 2021

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-190900-
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-
448 AM EDT Thu Mar 18 2021

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

.DAY ONE...Today and tonight.

Heavy showers and thunderstorms are likely to occur today. A few
storms may become strong to severe, producing damaging wind gusts,
hail, and an isolated tornado. The greatest threat for severe will
be along and southeast of interstate 85.

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

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
222 PM EDT Thu Mar 18 2021

SCZ007-181845-
Spartanburg SC-
222 PM EDT Thu Mar 18 2021

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL SPARTANBURG COUNTY UNTIL
245 PM EDT...

At 222 PM EDT, Doppler radar was tracking a strong thunderstorm 12
miles west of Spartanburg, or near Reidville, moving east at 40 mph.

Locations to be impacted include...
Spartanburg, Boiling Springs SC, Duncan, Lyman, Cowpens, Wellford,
Mayo, Roebuck, Reidville and Croft State Park.

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

LAT...LON 3485 8223 3496 8222 3514 8185 3507 8181
      3504 8181 3488 8174 3482 8218
TIME...MOT...LOC 1822Z 249DEG 33KT 3489 8213

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
225 PM EDT Thu Mar 18 2021

NCZ056-068>070-504-181900-
Gaston NC-Cleveland NC-Lincoln NC-Greater Burke NC-Catawba NC-
225 PM EDT Thu Mar 18 2021

...STRONG THUNDERSTORMS WILL IMPACT WESTERN CATAWBA...WESTERN
LINCOLN...CENTRAL CLEVELAND...NORTHWESTERN GASTON AND SOUTHEASTERN
BURKE COUNTIES UNTIL 300 PM EDT...

At 225 PM EDT, Doppler radar indicated strong thunderstorms along a
line extending from 13 miles south of Morganton to 9 miles west of
Shelby, and moving northeast at 45 mph.

Locations to be impacted include...
Hickory, Shelby, Cherryville, Longview, Boiling Springs NC, Belwood,
Lawndale, Fallston, Polkville and Lattimore.

Wind gusts up to 40 mph will be possible in these areas.

LAT...LON 3578 8130 3539 8135 3518 8171 3554 8168
TIME...MOT...LOC 1825Z 234DEG 40KT 3555 8165 3525 8170

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
258 PM EDT Thu Mar 18 2021

NCZ056-069-070-181945-
Gaston NC-Lincoln NC-Catawba NC-
258 PM EDT Thu Mar 18 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN CATAWBA...LINCOLN
AND NORTHWESTERN GASTON COUNTIES UNTIL 345 PM EDT...

At 257 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles southwest of Lincolnton, or 4 miles northeast of Cherryville,
moving northeast at 35 mph.

Locations to be impacted include...
Lincolnton, Cherryville, Maiden, Westport, Lake Norman, Boger City,
Iron Station, Denver, High Shoals and Sherrills Ford.

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

LAT...LON 3570 8099 3566 8096 3558 8095 3555 8096
      3553 8094 3553 8095 3550 8097 3534 8137
      3536 8141 3540 8144 3546 8146 3571 8101
TIME...MOT...LOC 1857Z 237DEG 31KT 3543 8133

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
312 PM EDT Thu Mar 18 2021

SCZ012-019-182000-
Laurens SC-Greenwood SC-
312 PM EDT Thu Mar 18 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTH CENTRAL LAURENS AND
CENTRAL GREENWOOD COUNTIES UNTIL 400 PM EDT...

At 311 PM EDT, Doppler radar was tracking a strong thunderstorm 4
miles south of Greenwood, moving northeast at 35 mph.

Locations to be impacted include...
Greenwood, Ninety Six, Cross Hill, Lake Greenwood State Park, Lake
Greenwood, Greenwood State Park, Ninety Six Historic Site, Promised
Land, Coronaca and Dyson.

Wind gusts up to 45 mph, nickel size hail and very heavy rainfall
rates up to 2 inches per hour 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 3413 8226 3416 8224 3420 8224 3424 8226
      3435 8199 3423 8192 3420 8194 3420 8193
      3418 8192 3418 8191 3416 8191 3414 8188
      3400 8223
TIME...MOT...LOC 1911Z 242DEG 41KT 3413 8216

KRENTZ

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
401 PM EDT Thu Mar 18 2021

NCZ070-071-182030-
Gaston NC-Mecklenburg NC-
401 PM EDT Thu Mar 18 2021

...A STRONG THUNDERSTORM WILL IMPACT NORTHERN MECKLENBURG AND EASTERN
GASTON COUNTIES UNTIL 430 PM EDT...

At 400 PM EDT, Doppler radar was tracking a strong thunderstorm 7
miles northeast of Gastonia, or over Mt Holly, moving northeast at 45
mph.

Locations to be impacted include...
Huntersville, Uptown Charlotte, Gastonia, Northeast Charlotte,
Northwest Charlotte, Cornelius, Mt Holly, Davidson, Belmont and
Dallas.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

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 3519 8112 3533 8119 3541 8104 3540 8096
      3543 8096 3546 8094 3551 8084 3551 8079
      3549 8079 3542 8075 3540 8077 3535 8069
      3527 8067 3526 8065
TIME...MOT...LOC 2000Z 243DEG 38KT 3530 8105

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
405 PM EDT Thu Mar 18 2021

NCZ037-057-182030-
Rowan NC-Davie NC-
405 PM EDT Thu Mar 18 2021

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN DAVIE AND NORTHWESTERN
ROWAN COUNTIES UNTIL 430 PM EDT...

At 404 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles northwest of Salisbury, or 4 miles northeast of Cleveland,
moving northeast at 35 mph.

Locations to be impacted include...
Mocksville, Salisbury, Cooleemee, Cleveland, Fork Church, Advance,
Piedmont Research Station and Woodleaf.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Gusty winds can blow down trees that are dead, or that have weakened
root systems. Outdoor furniture and similar items can be tossed
around if not anchored. Seek shelter indoors.

&&

LAT...LON 3588 8042 3587 8039 3585 8039 3585 8042
      3583 8043 3583 8046 3584 8047 3583 8049
      3579 8048 3577 8045 3574 8046 3572 8039
      3564 8064 3577 8074 3580 8072 3598 8042
      3596 8038 3589 8037
TIME...MOT...LOC 2004Z 240DEG 30KT 3576 8061

ARK