Severe Thunderstorm Warning 21, NWS Greenville-Spartanburg, SC

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
558 PM EST Thu Jan 12 2023

.SYNOPSIS...
A strong cold front will move through the area this evening
bringing rain and thunderstorms. Canadian high pressure will
build in behind the front on Friday and linger through the
weekend. A moist cold front will likely bring more precipitation
to our area on Tuesday, with high pressure briefly returning
on Wednesday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 550 PM EST Thursday: A Tornado Watch remains in effect through
10pm EST for the entire SC Upstate, portions of the NW NC Piedmont,
NC Foothills, and NE Georgia. SPC's meso analysis page shows 30-40
kts of 0-1 km Bulk Shear with 100-250 J/kg of SBCAPE in place across
the CWA. Thus, brief isolated tornadoes cannot be ruled out with
discrete cells tracking ahead of the main line. QLCS tornadoes are
also possible embedded within the line. The line of storms is
currently tracking east across the eastern two-thirds of the CWA.
This line is packing quite a punch bringing heavy downpours,
frequent lighting, and strong to damaging wind gusts. Main changes
needed to the fcst this evening was the increasing of PoPs based on
the latest radar loops.

Otherwise, for tonight, focus shifts to potential wintry impacts in
the mountains. As the cold front sweeps across the forecast area,
winds across the Appalachians will rapidly shift NWly and residual
deep-layer moisture will linger long enough for some snow showers in
the upslope zones along the NC-TN border.  Accumulations look fairly
light for tonight and into tomorrow morning.  However...stout NW
flow appears to continue through the day tomorrow, with an
increasingly convincing Great Lakes connection based on GFS
trajectories.  Ripples of upper vort energy will descend down the
back end of the departing longwave trough axis Friday afternoon and
evening...and the GFS/NAM as well as the RDPS depict 30-60 J/kg
sbCAPE developing over the Balsams and Smokies Friday evening.
This is accompanied by a widespread area of snow squall parameter
values of 1.5-2 across the entire Appalachians and maximized over
the Balsams.  Therefore, with ample low-level moisture likely still
in place Friday evening and overnight, there could be periods
of heavier snowfall where favorable upslope forcing intersects
good instability, and so accumulations have trended slightly
upward at the higher elevations along the NC-TN border counties.
The existing elevation-dependent Winter Weather Advisory / Winter
Storm Warning for those counties has not been modified, and will
still begin at midnight tonight to run through Saturday morning.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 235 PM Thursday: The short-term forecast picks up at 12z
on Saturday with broad upper trofing centered over the Eastern
Seaboard and steep upper ridging to the west. By early Sunday,
the trof axis will begin to move off the Atlantic Coast and upper
ridging will build in its wake. At the sfc, broad Canadian high
pressure will be spreading over our region from the NW as the
period begins early Saturday. NW flow will eventually weaken
late Saturday as the pressure gradient relaxes and the center
of high pressure drifts further east. Low-lvl moisture, however,
is expected to steadily dwindle early Saturday, and any lingering
NW flow snow showers should taper off Saturday morning, but we
could see a few flurries linger into the early afternoon along
the NC/TN border. Gusty winds will continue across the area thru
the day and eventually taper off Saturday night. The center of
the sfc high will move over our area on Sunday bringing dry wx
and near-normal temperatures.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 215 PM Thursday: The extended forecast picks up at 00z on
Monday with broad and deep upper trofing moving further off the
Atlantic Coast and upper ridging building over the Southeast in
its wake. On Monday, an embedded, southern-stream upper trof will
lift out of the southern Plains and ride up the ridge. The latest
guidance still has the trof axis passing to our north on Tuesday
and moving offshore by early Wed. As it does, the upper ridge will
amplify over the Southeast again and remain in place into Thurs.
As the period is ending on Thurs, another southern-stream embedded
upper trof will lift out of the SW CONUS and towards our region.

At the sfc, broad Canadian high pressure will be slowly moving
offshore on Monday as another cold front approaches from the west.
The front is still expected to move thru our fcst area on Tuesday
and be east of our CWA by late Tues/early Wed with brief drying
behind the front. A stronger cold front is expected to approach
our fcst area early Thursday as the period is ending. As for the
sensible fcst, no significant changes were needed with dry wx
on Monday and precipitation chances ramping up by early Tuesday.
Thunderstorm potential still appears minimal at best for the fropa
on Tuesday with little (if any) instability present over our area.
PoPs have increased marginally for Wed, but if any precip does
materialize, QPF should be minimal. Otherwise, temps will steadily
warm thru the period with values well-above climatology by mid-
week.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: It's the calm before the storm this
afternoon.  The western part of the forecast area remains socked
into a weak in situ wedge, resulting in a narrow corridor of IFR
cigs and fog roughly aligned with I-85 south of the NC/SC border.
In general...restrictions are beginning to lift as that residual
wedging begins to scatter out.  West of the forecast area, an
organized line of convection is pushing across the Mississippi
Valley and should impact all the terminals later this afternoon.
High confidence on some embedded TS along with scattered +SHRA
associated with this system.  The Upstate sites in particular are
likely to experience 25-30kt gusts as the line pushes through...and
ahead of the line some isolated areas of southerly LLWS are possible
as a robust low-level jet crosses the area.  Behind the line, a
cold front will sweep across the Carolinas and allow a wind shift
to W/NW overnight.  The ensuing gusty winds will mainly affect
the mountains...with mentionable gusts at KAVL and KHKY overnight.
Can't rule out some isolated areas of fog developing in sheltered
parts of the mountains, but in general winds look to be too strong
to support much fog.  Instead, clouds will slowly scatter out during
the overnight hours (with poor agreement among guidance sources
on how quickly this will occur) and give way to a generally clear
and dry day Friday.

Outlook: Dry high pressure builds in for the weekend, with limited
fog chances each morning in mountain valleys.  The next chance for
active weather and associated restrictions will come late Monday.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Winter Storm Warning above 3500 feet from midnight tonight to
     7 AM EST Saturday for NCZ033-048>052-058.
     Winter Weather Advisory below 3500 feet from midnight tonight
     to 7 AM EST Saturday for NCZ033-048>052-058.
SC...None.

&&

SYNOPSIS...JPT
NEAR TERM...AR/MPR
SHORT TERM...JPT
LONG TERM...JPT
AVIATION...MPR

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
456 PM EST Thu Jan 12 2023

GAZ018-026-028-029-NCZ035>037-056-057-068>072-082-507>510-SCZ008>014-
019-101>109-132200-
Stephens-Franklin-Hart-Elbert-Alexander-Iredell-Davie-Catawba-Rowan-
Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
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-
456 PM EST Thu Jan 12 2023

...TORNADO WATCH 23 IN EFFECT UNTIL 10 PM EST THIS EVENING...

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

   Tornado Watch.

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

No hazardous weather is expected at this time.

.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>052-058-132200-
Avery-Madison-Yancey-Mitchell-Swain-Haywood-Graham-
456 PM EST Thu Jan 12 2023

...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO 7 AM EST
SATURDAY ABOVE 3500 FEET...
...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 7 AM
EST SATURDAY BELOW 3500 FEET...

This Hazardous Weather Outlook is for 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.

   Winter Storm Warning.
   Winter Weather Advisory.

.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.

   Winter Storm Warning.
   Winter Weather Advisory.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to report snow and ice accumulations to our
office.

GAZ010-017-NCZ053-059-062>065-501>506-132200-
Rabun-Habersham-Buncombe-Northern Jackson-Macon-Southern Jackson-
Transylvania-Henderson-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
456 PM EST Thu Jan 12 2023

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

.DAY ONE...Tonight.

A strong cold front will bring some strong to severe storms to the
region this afternoon and evening. The main threats are cloud-to-
ground lightning and damaging wind gusts.

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

No hazardous weather is expected at this time.

.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.

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
600 PM EST Thu Jan 12 2023

NCZ037-122315-
Davie NC-
600 PM EST Thu Jan 12 2023

...A strong thunderstorm will impact portions of northern Davie
County through 615 PM EST...

At 600 PM EST, Doppler radar was tracking a strong thunderstorm 7
miles north of Mocksville, or 5 miles southeast of Courtney, moving
east at 55 mph.

HAZARD...Wind gusts up to 50 mph and nickel 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...
Bermuda Run and Farmington.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Tornado Watch remains in effect until 1000 PM EST for the Piedmont
of North Carolina.

&&

LAT...LON 3592 8062 3605 8066 3605 8050 3604 8049
      3605 8047 3606 8047 3606 8046 3603 8044
      3600 8041 3599 8042 3597 8038
TIME...MOT...LOC 2300Z 253DEG 49KT 3600 8057

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

MOORE

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