Severe Thunderstorm Warning 50, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
654 AM EDT Sat Apr 22 2023

.SYNOPSIS...
A cold front will cross the area today bringing showers and
a few thunderstorms. Dry and unseasonably cool high pressure will
build in behind the front Sunday through early next week. The next
chance for rain could arrived by midweek and lasts through the rest
of the work week as a series of low pressure systems move by to our
south.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 639 AM EDT Saturday: Forecast wasn't holding up well,
with widespread thunder in a fast-moving convective band sweeping
across the western Carolinas this morning.  No severe yet, but the
system has taken on a linear appearance which could support bowing
segments and damaging wind gusts.  Still sub-severe for now, and
the main line is alreaedy well east of I-26 and approaching the
Charlotte Metro area.

In any case, broad troughing over the Ohio Valley is expected to
translate east through this morning, driving a robust cold front
across the forecast area.  Associated rainfall is at its peak, and
should taper off as synoptic forcing begins lifting northward during
the day.  The real challenge remains determining the potential
for thunder early this afternoon.  By this point in time, the
front will be positioned well east of I-26, and it'll come down
to a race between developing sbCAPE along the I-77 corridor and
the advancing front. Ensemble guidance supports at least some deep
convection developing across the eastern zones after 15z...but RAP
and GFS profiles look marginally severe at best, boasting borderline
effective shear, unidirectional hodographs, and anemic lapse rates.
So, perhaps a few damaging wind gusts are possible, but the severe
threat looks limited overall.  SPC's Day 1 Marginal Risk along the
extreme eastern fringe of the forecast area thus looks reasonable.

This afternoon will feature gradual improvement as the front
translates east and dry cP air filters in.  Afternoon highs will
come in some 10-12 degrees cooler than yesterday's as a result of
the cold front.  Gusty NW flow will develop as low-level CAA peaks
during the late evening and first part of tonight.  Afternoon gusts
east of the mountains are poised to hit 20-25kts, with 30+ kt gusts
in the mountains persisting into the late evening...and should
taper off through the evening as CAA falters and the boundary
layer decouples.  By Sunday morning, clear skies and weakening
winds will permit temperatures to into the mid-40s east of the
mountains, and colder at high elevations.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 225 AM Saturday: The forecast area remains in near zonal flow
at the base of a low amplitude trough Sunday and Sunday night.
Heights rise slightly with more solid zonal flow Monday and Monday
night as the trough moves east. At the surface, a lee trough
develops Sunday between the departing cold front and high pressure
slowly building into the area from the west. The lee trough weakens
but remains Monday but remains in place before the center of the
high pressure moves into the central Appalachians Monday night.
There are some weak short waves moving over the area through the
flow and some moisture, but only clouds off and on clouds are
expected through the period. With the lee trough and deep mixing,
breezy to windy conditions are expected Sunday with lighter winds
but still potentially breezy conditions Monday. With the dry air
mass and downslope wind component, RH values could fall into the 25%
range both afternoons. The air mass will also be cold. Forecast lows
have been wavering somewhat, generally 5 to 10 degrees below normal,
creating the potential for frosty or freezing conditions both nights
across the mountains and the northern NC foothills. Highs around 5
degrees below normal Sunday then 5 to 10 below normal Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 255 AM Saturday: The upper low over the eastern Great Lakes
retrogrades somewhat Tuesday through Thursday keeping our area in
near zonal flow at the base of the resulting low amplitude trough. A
series of short waves move through the flow and across the area. A
stronger short wave moves from the southern Plains and into our area
Friday. The short wave moves east Saturday as a stronger upper low
drops into the mid-MS valley. At the surface, weak high pressure
sets up in a CAD position as waves of low pressure associated with
the short waves move by to our south. There are some timing
differences with these waves, but they all bring forcing, deep
moisture, and resulting precip to our area. They do agree on better
precip chances on Wednesday with a CAD developing. Therefore have
the highest PoP during that period. There could be a break in the
precip Thursday, have to lowest PoP then, then rain returns for
Friday with a CAD continuing. Moderate QPF is expected given the
forcing and deep moisture. Conversely, thunderstorms are expected
given the lack of instability in the CAD conditions. Lows rise to
near normal and remain nearly steady through the period. Below
normal highs Tuesday fall to 10 to 15 below normal Wednesday in the
rain and CAD, then back to 5 to 10 below normal the rest of the
period.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: As of 0530z, conditions remain VFR for all
terminals, but deterioration is imminent.  An approaching cold
front is currently entering the NC mountains and poised to promote
widespread -SHRA tonight and into the morning.  Most thunder has
vanished upstream as the system runs out of instability, and any
lingering instability looks shallow and unlikely to result in any
severe risk, so chose to forego mention of TSRA for all terminals
overnight...though can't rule out a passing rumble of thunder.
MVFR/IFR cigs expected during the predawn hours, when rainfall is
expected to be heaviest...lifting pretty quickly by late morning
as the system shifts east.  It remains questionable whether any
location within the CWFA will get any daytime thunder; with the
front running just ahead of the CAMs, it may push east before any
good surface instability can develop during the late morning/early
afternoon.  KCLT will likely be the only terminal with any real
thunder potential...so TSRA mentioned there after daybreak,
but still with shaky confidence and high false alarm potential.
By mid-afternoon, guidance depicts the system shifting east of the
I-77 corridor, and as dry air moves in on the backside of the front,
expect VFR conditions and gusty NW flow to build in for the tail
end of the TAF period.

Outlook: Dry high pressure promotes continued VFR conditions
Sunday into Monday.  Moisture will increase on Tuesday as the high
migrates east.

&&

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

&&

SYNOPSIS...RWH
NEAR TERM...MPR
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...MPR

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
405 AM EDT Sat Apr 22 2023

GAZ010-NCZ033-048>053-058-059-062>065-501-503-505-507-509-SCZ101>103-
230815-
Rabun-Avery-Madison-Yancey-Mitchell-Swain-Haywood-Buncombe-Graham-
Northern Jackson-Macon-Southern Jackson-Transylvania-Henderson-
Caldwell Mountains-Burke Mountains-McDowell Mountains-
Rutherford Mountains-Polk Mountains-Oconee Mountains-
Pickens Mountains-Greenville Mountains-
405 AM EDT Sat Apr 22 2023

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

.DAY ONE...Today and tonight.

Showers and a few thunderstorms will cross the area this morning.
Gusty winds, brief, heavy rainfall, and cloud-to-ground lightning can
be expected with any thunderstorm.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

A cold air mass moving into the area will bring the potential for
frosty or freezing conditions Sunday and Monday nights.

.SPOTTER INFORMATION STATEMENT...

None.

GAZ017-018-026-028-029-NCZ035-056-068>070-502-504-506-508-510-SCZ008-
010>013-019-104>109-230815-
Habersham-Stephens-Franklin-Hart-Elbert-Alexander-Catawba-Cleveland-
Lincoln-Gaston-Greater Caldwell-Greater Burke-Eastern McDowell-
Greater Rutherford-Eastern Polk-Cherokee-Anderson-Abbeville-Laurens-
Union SC-Greenwood-Greater Oconee-Greater Pickens-Central Greenville-
Southern Greenville-Northern Spartanburg-Southern Spartanburg-
405 AM EDT Sat Apr 22 2023

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

.DAY ONE...Today and tonight.

Showers and scattered thunderstorms will cross the area this morning.
A few of the storms may become strong with very gusty winds and small
hail.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ036-037-057-071-072-082-SCZ009-014-230815-
Iredell-Davie-Rowan-Mecklenburg-Cabarrus-Union NC-York-Chester-
405 AM EDT Sat Apr 22 2023

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

.DAY ONE...Today and tonight.

Showers and scattered thunderstorms will cross the area through early
afternoon. A few of the storms may become strong to severe with
damaging winds and large hail the main threats.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

None.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
529 AM EDT Sat Apr 22 2023

NCZ068-504-506>508-221000-
Greater Rutherford NC-Cleveland NC-Greater Burke NC-
Rutherford Mountains NC-Eastern McDowell NC-
529 AM EDT Sat Apr 22 2023

...A strong thunderstorm will impact portions of southeastern
McDowell, northern Rutherford, northwestern Cleveland and
southwestern Burke Counties through 600 AM EDT...

At 528 AM EDT, Doppler radar was tracking a strong thunderstorm 5
miles northwest of Rutherfordton, moving northeast at 50 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Rutherfordton, Morganton, Glen Alpine, Casar, South Mountains State
Park, Green Hill, Thermal City, Glenwood, Sunshine and Union Mills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 3575 8175 3549 8156 3534 8208 3535 8208
      3537 8211 3538 8211 3540 8213 3551 8217
      3552 8215 3553 8208 3558 8204
TIME...MOT...LOC 0928Z 240DEG 41KT 3543 8203

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

MPR

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Special Weather Statement
National Weather Service Greenville-Spartanburg SC
601 AM EDT Sat Apr 22 2023

NCZ510-SCZ008-010>013-106>109-221030-
Eastern Polk NC-Cherokee SC-Northern Spartanburg SC-
Central Greenville SC-Laurens SC-Southern Spartanburg SC-
Abbeville SC-Anderson SC-Union SC-Southern Greenville SC-
601 AM EDT Sat Apr 22 2023

...Strong thunderstorms will impact portions of southeastern Polk,
Laurens, southeastern Greenville, Spartanburg, east central Anderson,
western Cherokee, northeastern Abbeville and northwestern Union
Counties through 630 AM EDT...

At 600 AM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 11 miles northwest of Spartanburg to 13 miles
east of Greenville Downtown to 11 miles north of Abbeville. Movement
was northeast at 45 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Spartanburg, Gaffney, Laurens, Greenville Downtown, Greenville
Eastside, Greer, Mauldin, Taylors, Simpsonville and Clinton.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3433 8252 3487 8236 3512 8224 3512 8222
      3518 8221 3527 8199 3525 8196 3519 8196
      3517 8162 3441 8185 3437 8220 3441 8225
      3435 8232
TIME...MOT...LOC 1000Z 236DEG 40KT 3507 8205 3488 8215 3434 8232

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

RWH

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
629 AM EDT Sat Apr 22 2023

NCZ035-036-056-068>070-501-502-504-508-SCZ008-009-012>014-108-109-
221100-
Caldwell Mountains NC-Iredell NC-Cleveland NC-Lincoln NC-
Greater Burke NC-Greater Rutherford NC-Gaston NC-Greater Caldwell NC-
Alexander NC-Catawba NC-York SC-Cherokee SC-Laurens SC-
Southern Spartanburg SC-Chester SC-Northern Spartanburg SC-Union SC-
629 AM EDT Sat Apr 22 2023

...Strong thunderstorms will impact portions of Catawba, southeastern
Rutherford, Alexander, Lincoln, Gaston, northwestern Iredell,
Caldwell, Cleveland, southeastern Burke, Laurens, Union, northwestern
Chester, western York, Spartanburg and Cherokee Counties through 700
AM EDT...

At 628 AM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles west of Boomer to 10 miles southwest of
Hickory to 6 miles northeast of Gaffney to 10 miles northeast of
Greenwood. Movement was east at 35 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Gastonia, Hickory, Spartanburg, Shelby, Lenoir, Newton, Gaffney,
Lincolnton, Laurens and Union.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

&&

LAT...LON 3609 8145 3600 8133 3606 8093 3565 8097
      3518 8113 3445 8154 3448 8155 3453 8164
      3425 8191 3427 8205 3435 8217 3530 8195
      3555 8171 3612 8164
TIME...MOT...LOC 1028Z 260DEG 29KT 3603 8137 3560 8141 3513 8157 3431
8203

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

RWH