Damaging Wind in North Carolina, June 19, 2023

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1119 AM EDT Mon Jun 19 2023

.SYNOPSIS...
A low-pressure system developing over the Ohio Valley today will
usher in a prolonged period of wet and stormy weather throughout the
week as it drifts slowly over the Deep South. Numerous rounds of
showers and thunderstorms will develop east of this system over the
western Carolinas and northeast Georgia today and continue to
redevelop throughout the week, with locally heavy rainfall expected.
Shower and thunderstorm coverage will diminish slowly over the
weekend as the low pressure system lifts east.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 1112 AM EDT Monday: Through the early afternoon, most of the
thunderstorms and heavier rain potential looks like it will be along
and east of I-77 based on radar trends, as a 500 mb speed max and
lobe of DPVA move off to the east. Meanwhile, radar and satellite
imagery detect a mesolow moving northeast from the Lakelands to the
Upstate, with mostly light rain around the center. Thicker cloud
cover and patches of light rain will traverse the forecast area as
the mesolow moves overhead. It will take into the early afternoon
before the back edge of this activity moves past and we start to
destabilize for additional showers and storms. In the interim,
there should be a break in the action in many places.

The advancing stacked low to our west is progged to stall
somewhere over the upper Tennessee Valley or western Cumberland
Plateau through this evening. The big question mark remains
instability/shear profiles. The NAMnest features a stronger speed
max aloft and higher sfc dewpoints, supporting respectable deep
layer shear (30kts or more) and greater amounts of surface-based
instability (2500J/kg+) during peak heating.  The rest of the CAMs
are a little more muted in their convective parameters, which
bodes well for the severe risk this afternoon.  It'll largely
depend on how much cloud cover precedes the convective line as
it pivots across the area...but for now SPC's Day 1 Marginal
Severe Weather outlook seems reasonable.  With modest lapse rates
currently forecast and high DCAPE for most of the forecast area,
the primary severe threat still appears to be damaging winds.

Of greater interest is the heavy rainfall threat, and its
implications for later parts of the forecast.  Winds today will
be largely synoptically-driven, so confidence is fairly good that
a stout SE backed wind will develop east of the NC mountains as
flow curves around the advancing low.  Many guidance sources pick
up on a band of low-level convergence developing along the NC
Blue Ridge Escarpment, and doing so in an environment of 1.8-2.0"
PWs and deep warm cloud layers.  So, convectively-enhanced rain
rates may result in localized hydro issues along the Blue Ridge
Escarpment by this evening, especially if the SE low-level flow
results in any training cells along the Escarpment within the
advancing band of DPVA during the afternoon hours.  Additionally,
the 00z HREF depicts a band of 4" or higher QPFs through Tuesday
morning along the I-77 corridor, where several of its member models
are now forecasting repeat rounds of showery convection persisting
through Monday night.  All that to say, isolated hydro issues are
not out of the question going into tonight; what's difficult is
pinpointing where the greatest risk will be.  With dry antecedent
conditions across the board, nowhere do 6-hour QPFs exceed 6-hour
FFGs, even from more aggressive guidance sources like the ECMWF
and SREF...which is to say that flood advisories will likely be
favored over more flashy products through tonight.  With the jury
still out on whether the early issues will be along the Escarpment
zones with their higher overall totals, or over the I-77 corridor,
with its more runoff-prone ground, we have made the decision not
to issue a Flood Watch yet, and to see how things evolve today to
guide a possible better-informed issuance down the line.  WPC has
maintained a Slight Risk for Excessive Rainfall over most of the
forecast area today, which is in line with this thinking.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
As of 300 am EDT Monday: Given the extended nature of the expected
heavy rainfall event shaping up for Tuesday through Wednesday, it
seems increasingly likely that a Flash Flood Watch will be needed
for part or all of the western Carolinas and northeast Georgia - at
some point. The main reason for being cautious in issuing the watch
too early is that it may take several rounds of heavy showers and
thunderstorms in the near term to sufficiently prime the pump and
overcome some drier antecedent conditions and currently low stream
levels. Further, once a Watch is issued, it will likely be in place
for a rather long time, with the heavy rain potential now expected
to persist through late week. So, no watches will be posted with
this package, but messaging will continue in the Hazardous Weather
Outlook and with the daily Slight Risks of Excessive Rainfall.

For the specifics, the upstream 500 mb low center should be over
central Tennessee by Tuesday morning, continuing a slow southward
drift that will likely take it over Alabama through Wednesday. In
response to the low trajectory, more significant backing of the low-
level flow is expected over our area Tuesday through Tuesday night,
producing a stronger easterly upslope component into the eastern
escarpment of the southern Appalachians. The surface pressure
pattern suggests some weak or hybrid in situ cold air damming may
get established Tuesday given the parent high location near the New
England Coast. However, lingering low-level instability in the
numerical models suggests that parcels may not be trapped or dammed
east of the southern Appalachians in most locations south of I-40,
so we do not expect overwhelming stability to undercut precip rates
for the bulk of our area. Widespread heavy rainfall will thus
continue to redevelop atop the area, with an increasing focus on the
western NC foothills and Blue Ridge Mountains area. Maxes should be
capped at some 10 to 15 degrees below climo Tuesday afternoon.

The strong east to southeast fetch of Atlantic moisture will then
continue Wednesday through Wednesday night, likely causing any hydro
issues to mount. Cold air damming should strengthen a bit and should
start to limit instability more substantially across a greater chunk
of the forecast area on Wednesday. This may affect rainfall rates
across the region. Although the peak of the easterly flow 850 mb jet
on Wednesday will impact the Virginias, some maximization is also
likely along the northern Blue Ridge mountains of western NC, so the
rainfall numbers should continue to pile up even without high
convective rates. All told, rainfall totals should reach at least 3
to 5 inches in most areas by Wednesday night, with 5 to 8 inches
along the eastern slopes of the NC Blue Ridge Mountains, and with
more rainfall to follow in later periods. Gusty east to northeast
winds will maximize Wednesday, with some gusts to near 40 mph
possible in and near the northern Blue Ridge.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 315 am EDT Monday: The upper low center west of the southern
Appalachians may experience some retrograding motion westward on
Thursday as upper blocking persists from the Great Lakes to the
Northeast. Some degree of filling and lifting of the 500 mb low
center is then possible Friday through Saturday, but with varying
model solutions keeping the confidence low on when the heavy
rainfall will diminish. Low-level flow should veer toward southerly
Thursday through Friday, possibly refocusing the hydrology threat on
the extreme southern Appalachians. In addition, convective
instability could return and locally enhance precipitation rates
once again on Thursday and Friday. Any ongoing hydro problems will
likely persist, and new flooding could easily develop with much of
the area saturated by this point. Temperatures may start a slow
rebound, but with maxes likely staying near 10 degrees below climo
through late week.

The trough axis should migrate eastward through the weekend to
gradually end the hydro threat for our region. Precipitable water
values in profiles will fall back to near climo, but PoPs will
remain in the likely range through the weekend given the passing
trough. Temperatures will recover into the 80s over the weekend, but
still remain below normal values for late June.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
At KCLT and elsewhere: VFR conditions at all terminals for the
moment...but this won't last much longer.  As a deep stacked
low pressure system pivots across the Tennessee Valley tonight,
ripples of upper energy will begin to stream into the area during
the wee hours of Monday morning, prompting the first showers
across the western mountains and Upstate.  It now looks like
the first band of more coherent shower activity will arrive in
the Carolinas right around 12z, with enough instability for some
embedded thunder pretty much the same time shower activity picks
up at any one terminal.  For now, advertising VCSH/SHRA pushing in
from southwest to northeast during the 12-15z window, accompanied
at first by MVFR ceilings and VCTS.  By around 18z, all terminals
carry prevailing TSRA with MVFR to IFR ceilings.  By this time,
low MVFR to IFR visibility will also be warranted during periods
of heavier rain and thunder activity...and may persist through
much of the TAF period, even Monday night when the terminals will
go back to prevailing SHRA with just VCTS for embedded thunder.
Winds will pick up out of the SE after daybreak...and stay SSE
for much of the day, becoming increasingly ESE Monday night.

Outlook: Periods of numerous to widespread showers, thunderstorms,
and flight restrictions are expected through the remainder of the
week as the upper low stalls west of the area and becomes stagnant
over the Southeast.

&&

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

&&

SYNOPSIS...HG
NEAR TERM...MPR/PM
SHORT TERM...HG
LONG TERM...HG
AVIATION...MPR

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
350 AM EDT Mon Jun 19 2023

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ008>014-019-101>109-201000-
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-
350 AM EDT Mon Jun 19 2023

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

.DAY ONE...Today and tonight.

Waves of showers and embedded thunderstorms will cross the forecast
area from southwest to northeast today. Some of these storms will be
strong, producing gusty winds and frequent cloud-to-ground lightning
strikes. A few will probably become severe, capable of producing
damaging winds and large hail.

Additionally, localized flooding will be possible across most of the
forecast area today through tonight, as many locations will be
affected by multiple rounds of heavy rainfall. This should be
restricted mainly to low-lying areas and locations with poor
drainage.

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

Widespread showers and occasional thunderstorms will continue across
the region Tuesday through Wednesday. Torrential downpours falling on
increasingly saturated ground will steadily raise the threat of more
widespread flooding. Showers and thunderstorms may continue at times
on Thursday and Friday as well, possibly worsening any existing
flooding problems and potentially creating new flooding. The
persistent threat of heavy rainfall through the week may raise the
threat of landslides as well for locations in and near the mountains.

.SPOTTER INFORMATION STATEMENT...

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
631 AM EDT Mon Jun 19 2023

GAZ029-191130-
Elbert GA-
631 AM EDT Mon Jun 19 2023

...A strong thunderstorm with intense lightning will impact portions
of Elbert County through 730 AM EDT...

At 630 AM EDT, Doppler radar was tracking a strong thunderstorm 5
miles north of Lexington, or 4 miles north of Crawford, moving east
at 25 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...
Elberton, Bowman, Bobby Brown State Park, Russell State Park, Nancy
Hart State Park, Middleton, Lake Strom Thurmond, Lake Russell, Dewy
Rose and Fortsonia.

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 3399 8265 3397 8278 3401 8294 3403 8294
      3410 8304 3415 8306 3417 8310 3420 8309
      3423 8307 3423 8303 3421 8298 3425 8291
      3429 8277 3425 8274 3415 8272 3413 8268
      3409 8264 3407 8265 3403 8260 3396 8257
TIME...MOT...LOC 1030Z 251DEG 20KT 3395 8313

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
644 AM EDT Mon Jun 19 2023

SCZ010-102-103-105>107-191130-
Central Greenville SC-Anderson SC-Pickens Mountains SC-
Greater Pickens SC-Southern Greenville SC-Greenville Mountains SC-
644 AM EDT Mon Jun 19 2023

...Strong thunderstorms will impact portions of central Greenville,
Anderson and Pickens Counties through 730 AM EDT...

At 644 AM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from 10 miles northwest of Pickens to 6 miles east
of Clemson to 9 miles east of Hartwell. Movement was east at 30 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...
Greenville Downtown, Anderson, Easley, Clemson, Pickens, Greenville
Eastside, West Greenville, Mauldin, Berea and Welcome.

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 3427 8275 3435 8281 3462 8282 3490 8291
      3495 8291 3499 8294 3501 8291 3503 8292
      3509 8279 3507 8278 3510 8270 3513 8268
      3512 8266 3516 8255 3517 8249 3477 8227
      3453 8224 3424 8269 3422 8274
TIME...MOT...LOC 1044Z 254DEG 25KT 3497 8286 3468 8269 3431 8278

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
729 AM EDT Mon Jun 19 2023

SCZ011-191200-
Abbeville SC-
729 AM EDT Mon Jun 19 2023

...A strong thunderstorm will impact portions of southern Abbeville
County through 800 AM EDT...

At 728 AM EDT, Doppler radar was tracking a strong thunderstorm 12
miles southwest of Abbeville, or near Calhoun Falls, moving northeast
at 30 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Abbeville, Calhoun Falls, Lake Russell and Richard B Russell Dam.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

If on or near Lake Russell, get out of the water and move indoors or
inside a vehicle. Remember, lightning can strike out to 10 miles
from the parent thunderstorm. If you can hear thunder, you are close
enough to be struck by lightning. Move to safe shelter now! Do not
be caught on the water in a thunderstorm.

&&

LAT...LON 3407 8264 3409 8264 3412 8267 3431 8233
      3414 8225 3411 8226 3408 8230 3406 8238
      3406 8245 3408 8248 3407 8250 3407 8253
      3402 8259
TIME...MOT...LOC 1128Z 240DEG 28KT 3408 8256

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

LANE

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
1041 AM EDT Mon Jun 19 2023

NCZ036-057-071-191515-
Rowan NC-Iredell NC-Mecklenburg NC-
1041 AM EDT Mon Jun 19 2023

...A strong thunderstorm will impact portions of southeastern
Iredell, north central Mecklenburg and southwestern Rowan Counties
through 1115 AM EDT...

At 1041 AM EDT, Doppler radar was tracking a strong thunderstorm 6
miles north of Huntersville, or near Davidson, moving northeast at 25
mph.

HAZARD...Winds in excess of 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...
Cornelius, Mooresville, Davidson, Enochville, China Grove and Mount
Ulla.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3559 8056 3550 8071 3551 8078 3549 8079
      3548 8078 3547 8078 3544 8083 3549 8090
      3571 8073
TIME...MOT...LOC 1441Z 223DEG 23KT 3551 8082

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

LANE