Severe Thunderstorm Warning 233, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
615 PM EDT Sat Jul 9 2022

.SYNOPSIS...
A slow moving cold front will drift south of our area tonight
becoming stationary from east Texas to off the Carolina coast.
Cool high pressure to our north will usher in below-normal
temperatures for Sunday and Monday. Temperatures rebound to near
normal by mid- week as shower and thunderstorm chances increase
ahead of another cold front.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 607 pm EDT Saturday: Updated forecast to account for
convective trends, with still-growing complex of storms over
east/southeast part of Charlotte metro area. Obviously keeping
the likely precip prob over there, but not much going on elsewhere
across the fcst area with middling development to the cu field. The
SPC mesoanalysis still shows sfc-based CAPE of 1500-2000 J/kg
across the rest of the fcst area, however, so we will not give up
yet. Will reduce precip probs elsewhere for the next several hours,
until convection upstream approaches the NC mtns.

Otherwise...some initiation of deep convection over the mountains
is likely as the afternoon progresses, with activity spreading
eastward into the evening.  Due to weak deep shear, main severe
impact will be severe wind gusts. Some enhancement of coverage
relative to yesterday will be due to presence of a weak frontal
boundary at the surface which is a reflection of the passing
short wave aloft. Short wave moves across the GSP area tonight
and Sunday morning, dragging the surface front through the area.
Winds behind the front will be light northeasterly and will
serve to weaken dewpoints and to create considerable low-level
cloudiness. Thunderstorms greatly decrease in intensity behind the
front, but lighter showers will be possible at times most of the
day on Sunday.  CAPE behind front will be weak to non-existent, with
possible areas of instability being pushed southwestward during the
day. Passage of front with extensive cloudiness will keep a lid on
high temps Sunday, with highs running 10 plus degrees below normal.
Chances for any severe weather on Sunday is very limited, with
some possibility along the south and west edges of the GSP CWA.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
As of 230 PM EDT Saturday: The upper trough axis begins to propagate
east of our CWA Sunday evening, and behind the axis the mid- and
upper-levels of the atmosphere begin to dry out.  Our NEly fetch of
Atlantic moisture will gradually weaken Sunday night into Monday,
especially just above the surface around 925mb, which will reduce
the chances for light shower activity heading into Monday morning as
the low-levels of the atmosphere become less saturated.  However,
it will take most of the day on Monday for low-level NEly flow
to veer easterly and SEly, and as a result, any existing stratus
decks will too take some time to break up.  Nevertheless, the area
should expect increasing sunshine later Monday afternoon and before
sunset as remnant surface ridging erodes, with high temperatures
recovering 3-7 degrees across the northern Upstate and western
NC, where the cold dome was strongest.  Still these temperatures
will be about 4-7 degrees below normal and despite dewpoints
in the upper 60s, it will still feel pleasant enough for July.
The erosion of the low-level inversion later on Monday will be
counteracted by very poor mid-level lapse rates, but there may be
just enough instability, especially along the southern and western
edges of our area, to support isolated convection Monday afternoon.
Still, this does not appear to be of notable concern.

Our upper-level pattern is a bit stagnant later Monday through
Tuesday as the Deep South and southern Appalachians are underneath
a weakness/shear axis aloft caught between western US and Atlantic
subtropical ridges.  To our northwest is the next main system
as height falls aloft begin to amplify our next longwave trough.
Under this pattern our surface weather will be a bit more typical
for summer as light SWly flow returns.  A very small cap may be
in place according to forecast profiles during the peak heating
of the day on Tuesday, but temperatures aloft cool just enough
to increase lapse rates, instability, and, consequently, our
chances for isolated to scattered showers and thunderstorms.
Shear will be very weak given the overall pattern and there is
enough moisture aloft to limit downdraft CAPE, so any convection
that does develop isn't particularly concerning at this time.
Not surprisingly, the temperatures on Tuesday will also be quite
average for this time of year.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 230 PM EDT Saturday: The upper-level pattern will finally
begin to evolve Tuesday evening into Wednesday, as multiple
rounds of shortwave energy strengthen a longwave trough over
the eastern CONUS.  An attendant cold front will gradually
drift SE into the area on Wednesday, providing better focus for
more widespread shower and thunderstorm activity.  Thanks to the
strength of the approaching trough, bulk shear increases to a modest
20-25 kts on Wednesday and height falls support steepening lapse
rates and increasing SBCAPE values along and south of the front.
Furthermore, a strengthening SWly fetch of Gulf moisture around the
back of the Atlantic subtropical ridge will support increasing deep
moisture across the area, with PWs reaching 2 inches in some areas.
Therefore, Wednesday looks to be an active day across the area,
with perhaps an earlier onset closer to the front on the northern
edge of our area drifting south during the day. Some risk of
severe thunderstorms, heavy rainfall, and isolated flooding is a
reasonable expectation at this time.

The longwave trough becomes the dominant pattern aloft through
Friday and possibly into the weekend, though the model guidance
becomes a bit divergent that far into the extended.  Previous
hints of a focused area of mid-level vorticity marching across
the Southeast along a quasi-stationary front remain in some of the
latest deterministic runs, but only the ECMWF has been consistently
resolving a surface reflection of this vort max.  As of 12Z, the
ECMWF remains an outlier.  Nevertheless, the model's persistence
commands respect and future runs will have to be monitored to see
if other models start to trend in this direction.  Despite current
drought classifications, recent rainfall across much of the area
negates the need for widespread tropical moisture.

The key to any influence of tropical moisture over our area will
be the southward progression of the front, and here, guidance is
not in agreement as to just how far south the front will drift.
Compared to yesterday, the trend appears to be for the front to
stall somewhere over our area or just to our south.  As such,
PoPs remain elevated on Thursday with similar shear, temperature,
and moisture profiles, suggesting another potentially active day.
Confidence in the weather pattern Friday into Saturday decreases
further as the models diverge on whether or not any remnant boundary
can vacate the area and upper-level ridging can build back in.
For now, it appears the greater likelihood is for the weather to
remain unsettled with scattered showers and thunderstorms both days.
Fortunately, with troughiness the predominant large-scale pattern
and convective activity each day, temperatures will remain at or
slightly below normal through the period.

&&

.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
At KCLT and elsewhere: Diurnal afternoon thunder is in all the TAFs
for today, as previous days; however, change in airmass will remove
that possibility for tomorrow, with lighter, non-convective showers
possible much of the day.  Upper wave and surface front work its way
across the region this afternoon through Sunday.  As surface
boundary passes from northeast to southwest tonight and Sunday
morning, winds will become northeasterly, reducing instability and
ending thunder, but creating low stratus ceilings down to IFR or
LIFR. Low ceilings will likely persist all day on Sunday.  Behind
the front, winds will be generally northerly to northeasterly at 5
to 10 kts.

Outlook: Fog and low stratus will be possible each morning,
especially over any locations that receive rainfall from the
previous day. Convective activity will trend downward Sunday onward.

&&

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

&&

SYNOPSIS...DEO
NEAR TERM...PM/WJM
SHORT TERM...JMP
LONG TERM...JMP
AVIATION...WJM

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
449 AM EDT Sat Jul 9 2022

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ008>014-019-101>109-100900-
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-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
Oconee Mountains-Pickens Mountains-Greenville Mountains-
Greater Oconee-Greater Pickens-Central Greenville-
Southern Greenville-Northern Spartanburg-Southern Spartanburg-
449 AM EDT Sat Jul 9 2022

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

.DAY ONE...Today and tonight.

Scattered to numerous thunderstorms will develop across the region
again today, lingering into this evening. Any of these storms will
have the potential to produce frequent lightning, gusty winds, small
hail, and very heavy rainfall. A few of the storms may produce
damaging wind gusts of 60 mph or greater. Storms that are slow-moving
or train over the same areas may cause flash flooding, with the
greatest flood threat along the Interstate-77 corridor and east.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today. Please relay any severe
weather or flooding reports to the National Weather Service.

ARK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
523 PM EDT SAT JUL 09 2022

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

0945 PM     TSTM WND DMG     NEWTON                  35.66N 81.22W
07/08/2022                   CATAWBA            NC   TRAINED SPOTTER

            SMALL MAPLE TREE TOPPLED...TIME ESTIMATED FROM RADAR

&&

WIMBERLEY

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
535 PM EDT Sat Jul 9 2022

NCZ071-SCZ009-092200-
Mecklenburg NC-York SC-
535 PM EDT Sat Jul 9 2022

...Strong thunderstorms will impact portions of southern Mecklenburg
and east central York Counties through 600 PM EDT...

At 535 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 3 miles south of Uptown Charlotte to 8 miles
northwest of Indian Land. Movement was east at 15 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...
Charlotte, Matthews, Mint Hill, Pineville, Freedom Park and The
Plaza.

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.

&&

LAT...LON 3505 8075 3501 8084 3501 8085 3508 8091
      3503 8090 3502 8091 3504 8104 3524 8089
      3522 8057 3521 8055
TIME...MOT...LOC 2135Z 274DEG 12KT 3518 8087 3510 8094

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

8

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
600 PM EDT Sat Jul 9 2022

NCZ071-082-092245-
Union NC-Mecklenburg NC-
600 PM EDT Sat Jul 9 2022

...Strong thunderstorms will impact portions of southeastern
Mecklenburg and northern Union Counties through 645 PM EDT...

At 559 PM EDT, trained weather spotters reported strong thunderstorms
along a line extending from 12 miles east of Uptown Charlotte to 7
miles northeast of Indian Land. Movement was east at 25 mph.

HAZARD...Wind gusts of 40 to 50 mph and pea size hail.

SOURCE...Trained weather spotters and Doppler radar estimates.

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

Locations impacted include...
Monroe, Matthews, Mint Hill, Indian Trail, Weddington, Stallings,
Unionville, Wesley Chapel, Wingate and Lake Park.

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.

&&

LAT...LON 3510 8029 3495 8046 3501 8084 3522 8064
      3522 8057 3518 8050 3518 8048 3517 8047
      3516 8044 3517 8042 3516 8041 3518 8037
      3517 8036 3518 8031 3519 8030 3519 8028
TIME...MOT...LOC 2159Z 279DEG 20KT 3516 8064 3506 8074

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

8