Special Weather Statement, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1003 PM EDT Thu Jul 1 2021

.SYNOPSIS...
High pressure off the Atlantic coast weakens as a cold front drops
into the area from the Ohio River Valley on Friday. Increasing
moisture will lead to increasing coverage of showers and
thunderstorms on Friday. The front moves east and south of the area
by Saturday and Independence Day. Near seasonal conditions expected
early next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 945 pm EDT: The latest surface analysis depicts a cold front
stretching from southeast KY through central TN late this evening. A
deep moisture plume is in place along and ahead of the front, and
several rounds of pre-frontal showers and thunderstorms have already
worked over parts of the area this evening, with additional rounds
likely as the boundary pushes east into the southern Appalachians
overnight and upper support in the 500 mb trough arrives. A few of
the evening thunderstorms have been strong this evening. Although
instability will wane gradually overnight, deep layer shear will
experience a very slight uptick. However, lapse rates are not high
and this should limit any strong to severe potential overnight. The
main concern overnight through Saturday morning will be the
continued potential for heavy rainfall and isolated flooding.
Additional rounds of showers and thunderstorms likely to affect the
most primed locations near the TN border, so the current Flash Flood
Watch there appears on track. Rates will not be terribly high in the
mountains, but any training overnight could lead to flash flooding.
The rest of the area will see coverage improving, and the 1.75 to
2.0 inch precipitable water airmass will make isolated flooding
possible just about anywhere that training of cells occurs. The
latest excessive rainfall outlook Slight Risk area has been expanded
out over the I-77 corridor given the uptick in overnight convection
evident on the convection-allowing models. The potential for focused
training looks less east of the mountains, so no expansions to the
Flood Watch are expected.

The boundary will slowly cross the region on Friday. A brief uptick
in surface-based instabilty could herald the return of scattered
thunderstorms along the immediate front, especially across the
southeast half of the area. Maximum temps will be around 5 degrees
below normal, owing largely to extensive cloud cover that will be
stubborn to relent until fropa.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH MONDAY/...
As of 300 PM EDT Thursday: At the beginning of the period Friday
night, the cold front is expected to be moving through the
Piedmont such that by Saturday morning, dramatic changes to the
sensible weather will be well underway.  With a sprawling 1020mb
high pressure over the central Mississippi River Valley, a dry
continental airmass will overtake the region, setting us up for a
picture-perfect Independence Day long weekend.  Saturday will be
the blue-ribbon winner of the weekend with the lowest July 3rd high
temperatures since 2015, topping out about 5 degrees below-normal.
With dewpoints plunging into the lower to middle 50s by Saturday
afternoon, humidity values will be very comfortable across the
entire region.

Heading into July 4th, the high pressure will weaken and propagate
slowly east into the Ohio River Valley, keeping our winds light
and variable.  Dewpoints will creep back into the upper 50s
for Sunday and, as the high continues to weaken into Monday,
subtropical high pressure over the Atlantic will dominate our wind
field and weak southerly flow returns.  Therefore, expect another
incremental increase in dewpoints for Monday into the lower 60s,
but still fairly pleasant humidities for July.  Regardless, skies
will remain mostly sunny through the Monday holiday and though
high temperatures warm a couple of degrees each day, by Monday
they are just about normal for this time of year.  All-in-all,
it will be a perfect weekend for festivals and fireworks.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 300 PM EDT Thursday: Of course, all eyes are on tropical
cyclone Elsa for the extended period and her possible path
towards the southeast US, but tremendous uncertainty remains.
At the beginning of the extended on Tuesday, the upper-level
pattern is a bit complex with the Southeast coast underneath a
weakness aloft, a retreating subtropical ridge to the east, and a
shortwave ridge over the Ohio and Tennessee Valleys to the west.
Meanwhile, a strong shortwave trough is digging into the central
Great Plains and the Midwest while Elsa gets drawn into the
weakness between the approaching trough and the retreating ridge.
As is often the case in the midlatitudes, the exact track will be
determined by the speed and amplitude of the incoming trough and
the strength and westward expansion of the subtropical ridge.
Ensemble track guidance from overnight had extreme spread and
the official NHC forecast generally reflects the mean of the
broadly distributed track guidance.  The deterministic 12Z GFS and
Canadian solutions bring Elsa up into the Carolina coastal plain
or coastline Wednesday night through Thursday night, with a ~150
mile spread of the low-pressure center between the two, whereas the
12Z ECMWF continues the solution of previous runs and dissipates
the cyclone over the rugged terrain of Hispaniola.  What is left
of Elsa is absorbed into the offshore stationary front as an open
tropical wave.  Clearly, there is no justification for focusing
on one solution or another this far out and our best advice is to
enjoy your long weekend and keep an eye on the forecast heading
into early next week.

At a broad level, our forecast will gradually become more unsettled
Tuesday through Thursday next week as moisture returns to the
region in advance of the shortwave trough to our west and the
subtropical ridge to our east.  Expect slight chance pops for
Tuesday afternoon increasing to solid chance pops Wednesday
and Thursday.  Generally unsettled conditions may persist into
Friday even if Elsa lifts well to the NE of our region, as the
upper-level trough that settles into our area late next week may be
slow to depart the area.  High temperatures through the extended
are currently forecasted to remain near to slightly above-normal
with humidity values more typical of a subtropical airmass.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: Coverage of showers and thunderstorms will
steadily grow across the terminal forecast area late this evening
and overnight as a cold front pushes east into the southern
Appalachians. This will be addressed with TEMPO TSRA at most sites
over the next few hours, morphing into longer lasting periods of
SHRA, with PROB30 TSRA nearer the fropa on Friday. Abundant moisture
will permit brief IFR conditions under the heavy downpours, but then
IFR cigs forming at most sites toward daybreak. The low clouds will
be very slow to lift and eventually scatter as the boundary crosses
the region slowly on Friday. Winds remain SW at 10 kt or less ahead
of the front, aside from any thunderstorms. Anticipate VFR
conditions returning mid to late afternoon, along with a wind shift
to W or NW with the fropa.

Outlook: Drying is expected from Saturday into early next week.
Diurnal showers and thunderstorm chances, along with the potential
for mainly mountain valley morning fog/low stratus will return by the
middle of next week.

Confidence Table...

            02-08Z        08-14Z        14-20Z        20-00Z
KCLT       High  90%     Med   72%     Med   72%     High 100%
KGSP       High  91%     Med   75%     Med   72%     High 100%
KAVL       Low   54%     Med   61%     Med   64%     High 100%
KHKY       High  89%     Med   69%     Med   77%     High 100%
KGMU       High  83%     Med   76%     Med   74%     High 100%
KAND       High 100%     Med   72%     Med   73%     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...Flash Flood Watch until 8 AM EDT Friday for NCZ033-048>052-058.
SC...None.

&&

SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...HG

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
452 PM EDT Thu Jul 1 2021

GAZ010-017-018-026-028-029-NCZ035>037-053-056-057-059-062>065-
068>072-082-501>510-SCZ001>014-019-022100-
Rabun-Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Iredell-
Davie-Buncombe-Catawba-Rowan-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-
452 PM EDT Thu Jul 1 2021

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

.DAY ONE...Tonight.

Showers and thunderstorms will increase in coverage and intensity
from the west tonight ahead of a cold front tonight. Cloud-to-
ground lightning and very gusty winds can occur with any of these
thunderstorms. Areas of heavy rainfall will be possible, potentially
leading to isolated flash flooding, especially across the mountains.

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

Showers and thunderstorms will cross the area Friday as the cold
front moves southeast across the region. Cloud-to-ground lightning
and very gusty winds may continue with any of the storms. Areas of
heavy rainfall will be possible, potentially leading to isolated
flash flooding. Rainfall will quickly move east of the area Friday
evening.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information
about observed severe weather to the NWS while following all
local, state, and CDC guidelines.

NCZ033-048>052-058-022100-
Avery-Madison-Yancey-Mitchell-Swain-Haywood-Graham-
452 PM EDT Thu Jul 1 2021

...FLASH FLOOD WATCH IN EFFECT THROUGH FRIDAY MORNING...

This Hazardous Weather Outlook is for the Tennessee border counties
of the mountains of western North Carolina.

.DAY ONE...Tonight.

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

   Flash Flood Watch.

In addition to the heavy rainfall threat, the increasing coverage of
thunderstorms will generate cloud-to-ground lightning and very gusty
winds through tonight.

.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.

   Flash Flood Watch.

Showers and thunderstorms will cross the area Friday as the cold
front moves southeast across the region. Cloud-to-ground lightning
and very gusty winds may continue to occur with any of the storms.
Rainfall will quickly move east of the area by late Friday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Please relay any information
about observed severe weather to the NWS while following all
local, state, and CDC guidelines.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
909 PM EDT Thu Jul 1 2021

NCZ057-072-020145-
Rowan NC-Cabarrus NC-
909 PM EDT Thu Jul 1 2021

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN CABARRUS AND
SOUTHEASTERN ROWAN COUNTIES UNTIL 945 PM EDT...

At 909 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles east of Kannapolis, or 4 miles southwest of Rockwell, moving
northeast at 40 mph.

Locations to be impacted include...
Salisbury, Spencer, Granite Quarry, Rockwell, Faith, High Rock Lake,
Mt Pleasant, Gold Hill and High Rock.

Wind gusts up to 55 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 3540 8044 3552 8061 3573 8043 3573 8039
      3572 8038 3572 8034 3571 8032 3570 8033
      3568 8033 3567 8031 3563 8029 3562 8025
      3558 8021
TIME...MOT...LOC 0109Z 221DEG 33KT 3552 8047

ARK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
924 PM EDT THU JUL 01 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0753 PM     TSTM WND DMG     1 W TEGA CAY            35.03N 81.03W
07/01/2021                   YORK               SC   BROADCAST MEDIA

            BROADCAST MEDIA REPORTED TREES DOWN AND PATIO FURNITURE
            TOSSED

&&

MPR

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
940 PM EDT Thu Jul 1 2021

GAZ018-026-028-SCZ004-010-020215-
Hart GA-Franklin GA-Stephens GA-Greater Oconee SC-Anderson SC-
940 PM EDT Thu Jul 1 2021

...A THUNDERSTORM WITH TORRENTIAL RAINFALL WILL IMPACT NORTHEASTERN
FRANKLIN...SOUTHEASTERN STEPHENS...NORTHERN HART...WEST CENTRAL
ANDERSON AND SOUTHEASTERN OCONEE COUNTIES UNTIL 1015 PM EDT...

At 940 PM EDT, Doppler radar was tracking a thunderstorm with
torrential rainfall 9 miles northeast of Carnesville, or near Gumlog,
moving east at 30 mph.

Locations to be impacted include...
Reed Creek, Lavonia, Gumlog, Martin, Avalon, Tugaloo State Park, Lake
Hartwell, Bowersville, Townville and Fair Play.

Very heavy rainfall rates up to 2 inches per hour 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 3451 8324 3467 8286 3464 8285 3462 8285
      3462 8284 3442 8275 3436 8317
TIME...MOT...LOC 0140Z 247DEG 26KT 3447 8312

ARK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1016 PM EDT THU JUL 01 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0941 PM     TSTM WND DMG     1 NE SALISBURY          35.67N 80.48W
07/01/2021                   ROWAN              NC   EMERGENCY MNGR

            EM REPORTS TREE DOWN

&&

MPR

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1030 PM EDT Thu Jul 1 2021

GAZ028-SCZ004-006-010-020315-
Hart GA-Greater Oconee SC-Anderson SC-Greater Greenville SC-
1030 PM EDT Thu Jul 1 2021

...THUNDERSTORMS WITH TORRENTIAL RAINFALL WILL IMPACT NORTHEASTERN
HART...SOUTHEASTERN GREENVILLE...ANDERSON AND SOUTHEASTERN OCONEE
COUNTIES UNTIL 1115 PM EDT...

At 1028 PM EDT, Doppler radar was tracking thunderstormS with
torrential rainfall from 11 miles west of Anderson, or near Lake
Hartwell to 2 miles west of Mauldin, moving east at 35 mph.

Locations to be impacted include...
Anderson, Greenville Downtown, Greenville Eastside, Homeland Park,
Powdersville, Piedmont, Belton, Williamston, Northlake and Pendleton.

Very heavy rainfall rates up to 2 inches per hour 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 3440 8289 3459 8297 3464 8284 3463 8285
      3462 8285 3467 8279 3486 8236 3457 8224
TIME...MOT...LOC 0228Z 247DEG 32KT 3452 8284

ARK

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1043 PM EDT Thu Jul 1 2021

NCZ037-020315-
Davie NC-
1043 PM EDT Thu Jul 1 2021

...A STRONG THUNDERSTORM WILL IMPACT CENTRAL DAVIE COUNTY UNTIL 1115
PM EDT...

At 1043 PM EDT, Doppler radar was tracking a strong thunderstorm 5
miles northeast of Mocksville, or 4 miles southwest of Bermuda Run,
moving east at 20 mph.

Locations to be impacted include...
Mocksville, Bermuda Run, Fork Church, Advance and Farmington.

Wind gusts up to 40 mph 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 3589 8040 3588 8042 3587 8039 3585 8039
      3586 8059 3605 8059 3604 8049 3606 8046
      3603 8044 3600 8041 3599 8042 3596 8038
      3589 8037
TIME...MOT...LOC 0243Z 268DEG 18KT 3597 8050

ARK