Severe Thunderstorm Warning 302, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
252 PM EDT Mon Aug 14 2023

.SYNOPSIS...
A weak cold front will drift slowly from Tennessee and across our
area tonight and reach the eastern Carolinas by Tuesday night.
Expect a few strong to severe storms ahead of the front. As drier
high pressure builds across our region in mid week, we will have
milder temperatures and lower humidity into late week.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 145 PM EDT Monday: The leading outflow from this morning's
convective activity is now pushing into the NC mountains, and
is triggering some new storms. The more bullish 12z NAMnest and
FV3 CAMs are verifying the best with this, and they keep building
more storms as the boundary pushes east across the forecast area
this aftn into early evening. They may still be overdone, but the
latest SPC mesoanalysis page shows uncapped MLCAPE of 1500-2500
J/kg across the Piedmont. Effective shear is pretty weak, but is
expected to increase across western NC thru the aftn to about 30
kt. So a few multicell clusters may form, increasing the damaging
wind threat. PoPs were tweaked to show more solid chances across
the NC Piedmont and northern and eastern SC Piedmont.

Activity should wane and/or push east early this evening. However,
another round of convection is expected to form along an approaching
cold front across eastern TN/KY. The deep-layer flow is progged
to back to west-southwesterly, becoming more parallel to the
boundary. So this activity is expected to be less organized, but
may cause some training cells and an excessive rainfall threat. The
12z HREF probability-matched mean QPF keeps the axis of heaviest
rainfall across the Great TN Valley, but with a tight gradient
along the TN/NC border. Confidence is too low for any kind of Flood
Watch, but isolated flooding near the TN border cannot be ruled
out tonight. Otherwise, cloud cover from the eastern TN convection
will probably help keep temps elevated and limit mountain valley
fog formation. Lows expected to be in the upper 60s to 70 in the
mountain valleys and low to mid 70s across the Piedmont.

The front should push across the forecast area during the day
Tuesday, as a strong shortwave/upper low swings across the OH
Valley. The front is likely to be near the eastern edge of the
Blue Ridge around midday, when diurnal destabilization picks up and
convection initiates. MLCAPE will likely be over 2000 J/kg east of
the mountains, and effective shear around 30-40 kts, allowing for
some storm organization. The HRRR has been showing updraft helicity
swaths, with a quasi-supercell storm mode across the eastern third
of the forecast area. The updated Day 2 SPC convective outlook
has a marginal risk extended back west across our entire Piedmont,
with a slight just into Rowan and Cabarrus counties. If the frontal
timing slows much more, the slight risk may be extended further
west into our area. Temps should be a little cooler in the west
thanks to the fropa, while the southeast corner will see another
hot and humid day, with heat indices in the 100-105 range.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 213 PM Monday: Expect the frontal boundary to still be
lurking over the southeastern zones at sunset on Tuesday, with
some storms along the front primarily around metro Charlotte,
but this activity should continue to move out of the fcst area
thru mid-late evening. By daybreak Wednesday we should notice the
air mass change with a continental high building in from the west
with much drier air. The center of the high will remain to our
west and gradually weaken on Wednesday and Thursday while the old
front has stalled along the coast. The proximity of the front might
keep a few showers/storms just to the southeast of the fcst area
on Wednesday and Thursday afternoon and the fcst will keep that,
even though it is much more likely the convection will be to our
east both days. Temps will be a welcome relief on Wednesday...maybe
a category below normal with low dewpoints...and still a degree
or two below normal for Thursday.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 113 PM Monday: The latest model guidance shows a subtle trend
back toward more confidence in a dry solution for the end of the
week into early next week. The main player will be the sprawling
upper anticyclone over the Plains, the center of which may migrate
from OK to IA through the medium range period. The eastern extent
of the anticyclone is shown to gradually expand eastward over the
weekend to eventually envelop the entire forecast area in even
the slowest guidance. The immediate effect will be to suppress
deep convection with a formidable cap and relatively dry boundary
layer, such that even the usual ridgetop shower activity appears
unlikely through the weekend. By Monday, there could be enough
modification to the air mass to allow for some mountain afternoon
convection. For the time being, at least, temperature guidance
looks close to normal, with a warming trend as we start the new
week. Looking ahead, the big question is when/if the center of
the upper anticyclone will ever make it east of the MS River,
and it looks like the answer so far is...not yet.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Convection is firing along a leading boundary
from early morning activity, pushing into western NC. Confidence is
increasing that scattered TSRA will form across the area this aftn,
so have VCTS and/or TEMPOs for TS at all sites. Activity should exit
to the east and wane early this evening. Then overnight, another
round of convection is expected near the TN/NC border. Some of this
may affect KAVL, but most is expected to stay NW. Cloud cover from
this activity may limit mountain valley fog development, but will
show at least a hint of some restrictions at KAVL early Tuesday
morning. A cold front will push across the area during the day
Tuesday, and is expected to trigger a broken line of convection
roughly along the Blue Ridge. The showers and tstms will then
track east across the Piedmont thru the aftn.

Outlook: A cold front is expected to stall just east of the area,
allowing drier air to filter in from the NW on Wednesday and beyond.
Mountain valley fog and low stratus will be possible each morning.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ018-026-028-
     029.
NC...Heat Advisory until 8 PM EDT this evening for NCZ070-071-082.
SC...Heat Advisory until 8 PM EDT this evening for SCZ009>014-019-
     104-105.

&&

SYNOPSIS...DEO
NEAR TERM...ARK
SHORT TERM...PM
LONG TERM...PM
AVIATION...ARK

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
541 AM EDT Mon Aug 14 2023

GAZ010-NCZ033-035-048>053-058-059-062>065-501>507-509-SCZ101>103-
150945-
Rabun-Avery-Alexander-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-
Graham-Northern Jackson-Macon-Southern Jackson-Transylvania-
Henderson-Caldwell Mountains-Greater Caldwell-Burke Mountains-
Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Polk Mountains-Oconee Mountains-
Pickens Mountains-Greenville Mountains-
541 AM EDT Mon Aug 14 2023

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 are expected at times through Tuesday
morning. Any of these storms may produce dangerous cloud-to-ground
lightning, gusty winds, and locally heavy rainfall. A few
thunderstorms may pose an additional risk of severe weather, in the
form of damaging wind gusts, and/or hail the size of a quarter or
larger. The greatest risk of severe weather may actually develop
before dawn Tuesday ahead of an approaching cold front.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

GAZ017-NCZ036-037-056-057-068-069-072-508-510-SCZ008-106>109-150945-
Habersham-Iredell-Davie-Catawba-Rowan-Cleveland-Lincoln-Cabarrus-
Greater Rutherford-Eastern Polk-Cherokee-Central Greenville-
Southern Greenville-Northern Spartanburg-Southern Spartanburg-
541 AM EDT Mon Aug 14 2023

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 are expected this afternoon and evening. Any
of these storms may produce dangerous cloud-to-ground lightning,
gusty winds, and locally heavy rainfall. A few thunderstorms may pose
an additional risk of severe weather, in the form of damaging wind
gusts, and/or hail the size of a quarter or larger.

Also, heat index may rise above 100 this afternoon, possibly
reaching 105 in a few locations. These conditions may pose a risk of
heat-related illness in sensitive groups such as the elderly.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

A few thunderstorms developing again Tuesday afternoon may produce
localized damaging wind gusts, and/or hail the size of a quarter or
larger.

.SPOTTER INFORMATION STATEMENT...

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

GAZ018-026-028-029-NCZ070-071-082-SCZ009>014-019-104-105-150945-
Stephens-Franklin-Hart-Elbert-Gaston-Mecklenburg-Union NC-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-Greater Oconee-
Greater Pickens-
541 AM EDT Mon Aug 14 2023

...HEAT ADVISORY IN EFFECT FROM 11 AM THIS MORNING TO 8 PM EDT THIS
EVENING...

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

.DAY ONE...Today and tonight.

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

   Heat Advisory.

Also, scattered thunderstorms are expected this afternoon and
evening. Any of these storms may produce dangerous cloud-to-ground
lightning, gusty winds, and locally heavy rainfall. A few
thunderstorms may pose an additional risk of severe weather, in the
form of damaging wind gusts, and/or hail the size of a quarter or
larger.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

A few thunderstorms developing again Tuesday afternoon may produce
localized damaging wind gusts, and/or hail the size of a quarter or
larger. Heat index is not likely to be as high as Monday, but still
may top 100, and this may may pose a risk of heat-related illness in
sensitive groups such as the elderly.

.SPOTTER INFORMATION STATEMENT...

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

Wimberley

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
307 PM EDT Mon Aug 14 2023

NCZ036-037-057-141930-
Rowan NC-Davie NC-Iredell NC-
307 PM EDT Mon Aug 14 2023

...A strong thunderstorm will impact portions of western Davie,
northern Iredell and northwestern Rowan Counties through 330 PM
EDT...

At 306 PM EDT, Doppler radar was tracking a strong thunderstorm 9
miles north of Statesville, or 6 miles southeast of Love Valley,
moving east at 25 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Statesville, Mocksville, Harmony, Cleveland, Love Valley, Stony
Point, Turnersburg, Olin, Cool Springs and Sheffield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3601 8052 3581 8057 3568 8075 3584 8105
      3587 8104 3597 8100 3602 8096
TIME...MOT...LOC 1906Z 291DEG 23KT 3591 8092

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
327 PM EDT Mon Aug 14 2023

NCZ036-037-057-142000-
Rowan NC-Davie NC-Iredell NC-
327 PM EDT Mon Aug 14 2023

...A strong thunderstorm will impact portions of Davie, northeastern
Iredell and northwestern Rowan Counties through 400 PM EDT...

At 327 PM EDT, Doppler radar was tracking a strong thunderstorm 10
miles west of Mocksville, or 4 miles southeast of Harmony, moving
east at 25 mph.

HAZARD...Wind gusts up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Mocksville, Statesville, Bermuda Run, Cooleemee, Harmony, Cleveland,
Fork Church, Advance, Turnersburg and Cool Springs.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3589 8037 3589 8040 3588 8042 3587 8039
      3585 8039 3585 8042 3583 8043 3584 8048
      3583 8049 3579 8048 3577 8045 3572 8046
      3570 8049 3578 8086 3602 8079 3604 8045
      3601 8042 3599 8042 3596 8038
TIME...MOT...LOC 1927Z 279DEG 21KT 3590 8074

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

HG

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