Winter Weather in Georgia, January 7 to 8, 2021

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
637 PM EST Thu Jan 7 2021

.SYNOPSIS...
A moist storm system arrives from the west tonight and will pass
east of the area Friday through Friday night. Widespread wintry
weather is expected for many locations with this system, with the
best chances and most significant accumulations over the mountains
and foothills. Canadian high pressure returns to the region over the
weekend. Another low pressure system is likely to affect the area
early next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 620 pm EST: Regional radars show the leading edge of the first
stratiform precipitation shield spreading over the area from the
southwest this evening. The heavier 35+ dBZ elements have
corresponded with pockets of sleet or light snow and an SPS has been
issued to address this in areas outside of the existing Warnings and
Advisories. The vertical profiles from the 18Z model runs looked
quite similar thermodynically to the 12Z runs and a top down
approach to the weather precipitation types suggests little change
to the current forecast accumulations. No hazard adjustments will be
made based on the latest runs.

Otherwise, the latest WV imagery reveals the approaching upper
cyclone centered near the MS/AL/TN border, with strongly diffluent
flow downstream over much of the Deep South and the TN Valley.
Forcing and moisture ahead of this system will increase rapidly
across our forecast area through the nighttime hours, with precip
chances ramping up quickly across the region. Surface ridge
extending from surface anticyclone over Ontario will spill into the
area through the period, resulting in increasing low-level NE flow
and gradually advecting lower wet bulb temp air into the forecast
area. With wet bulb temps are already around freezing across much of
the NC mtns, those areas are poised to see almost exclusively snow
as the precip develops and intensifies. The Little TN Valley and
adjacent valleys are warmer as usual, and will likely see almost as
much RA as wintry precip.

Locations east of the mountains will be more problematic and pytpes
will depend more heavily on temperature trends in the lowest 1000'
or so. While all locations east of the mtns will more than likely
start out with rain, mixed briefly with sleet, advection of the
lower wet bulb air should support a transition to snow along and
north of I-40, and in fact, precip should be more frozen than not in
those areas. Closer to the I-85 corridor, things get a lot trickier.
Guidance generally agrees that mostly rain will be seen closer to
the NC/SC border. However, periods of stronger synoptic forcing will
support high precip rates at times tonight (classic "cross-hair
signature" indicated in model cross sections), and this may force
periods of a mix with or transition to SN, although how much that
would be able to accumulate is debatable. Another source of
uncertainty is the potential for a narrow band of mixed precip, most
likely sleet, but a brief period of FZRA can't be ruled out, as the
NAM has been consistent in developing a warm nose, albeit not a
particularly strong one near the NC/SC border tonight. Since the NAM
usually does a good job in capturing these features, even when other
guidance does not, we continue to forecast a region of sleet from
the GA/SC/southern NC mtns into the Piedmont. Forecast accumulation
is minimal, but this does create another pitfall for the snow accum
forecast.

Of greater concern for areas east of the mtns, and especially the
Piedmont and  I-77 corridor, will be the potential for mesoscale
banding during the daylight hours Friday, as a deformation zone
matures in response to cyclone deepening off the coast. Convection-
allowing models, especially those that are NAM-based and even the
operational NAM itself depict potential for locally high precip
rates, esp across the Piedmont from late morning into the afternoon,
possibly resulting in quickly accumulating snowfall, even in areas
outside the warning. Of course, predicting where exactly this will
(or if it will) set up is akin to predicting where a cluster of
thunderstorms will develop 24 hours in advance. Nevertheless, the
potential exists for locally intense snowfall rates tomorrow,
especially across the Piedmont.

In terms of amounts: storm totals are forecast to range from 5 to 10
inches across the NC mtns, except more in the 1-3 inch range across
the valleys of far southwest NC and over much of Rabun County GA.
Four to six inches are expected across the northern NC foothills,
where a developing stout easterly flow is expected to enhance precip
rates tonight, while 2-4 inches are generally forecast for the
northwest NC Piedmont. General 1-2 inch amounts are forecast in the
Advisory areas detailed above, although the southern part of those
zones may see little to no accum.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 130 PM EST Thursday: Northwest flow snow showers may linger
into early Saturday morning before low level moisture drys out.
Additional light accumulations are possible near the Tennessee
border. Dry high pressure will build into the region to support
sunny and cool conditions this weekend. Where a healthy snowpack
persists, diurnal melting of the snow and well below freezing
temperatures at night may allow for a lingering black ice threat.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 145 PM EST Thursday: Low confidence continued for the
extended portion of the forecast. Model guidance continues to
struggle with a possible winter storm early next week. The latest EC
has trended towards the GFS and its ensembles towards a more
suppressed, colder system. It seems guidance is struggling with how
much if any phasing of the southern northern stream jets will occur.
The forecast continues to feature mountain snow showers with
transition of rain/snow showers across the Piedmont and rain for far
southern areas late Monday into Tuesday. It appears cold and mostly
dry west/northwest flow will prevail later in the week as general
troughiness remains in place.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: A shield of more solid precipitation has
filled in quickly from the southwest this evening, but with plenty
of low to mid-level dry air to inhibit lowering cigs and any precip
rates. Anticipate lowering VFR bases early on, quickly dropping to
MVFR through the evening hours, and becoming IFR overnight as
profiles saturate. Most locations should get locked into the IFR
range, with LIFR possible at times, for the rest of the terminal
forecast period. Ptypes will be quite the concern throughout, with
sleet mixing in at all sites briefly at onset, but with primarily
rain at the Upstate sites and KCLT, and primarily snow at KAVL and
KHKY as the profiles saturate. Expect sleet and possibly snow to mix
at times through Friday morning even for the Upstate sites and KCLT
as profiles cool from the top down as the 850 mb low center moves
east. The main question mark for heavier snow showers and rapidly
lowering cigs and vis Friday will be where the banding of
precipitation sets up through the day. Anticipate that nearly all
sites will have a decent shot of at some moderate or better snow
bands in the afternoon or evening hours, with the best chances
across the NC TAF sites including KCLT. Anticipate NE winds, gusty
at times, east of the mountains, with SE flow at KAVL early turning
back to the NW.

Outlook: Some improvement in flight conditions is possible Friday
night in the wake of the storm system. Drying is expected over the
weekend. Another storm system may impact the area Monday night into
Tuesday with precipitation and associated restrictions.

Confidence Table...

            23-05Z        05-11Z        11-17Z        17-18Z
KCLT       High 100%     High  80%     Med   70%     High  94%
KGSP       High 100%     High  80%     High 100%     High  89%
KAVL       High 100%     High  85%     High  90%     Med   78%
KHKY       High 100%     Med   75%     High 100%     High  89%
KGMU       High 100%     High  85%     High  95%     High  89%
KAND       High 100%     Med   60%     Med   70%     Med   66%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Winter Weather Advisory until midnight EST Friday night for
     GAZ017.
     Winter Storm Warning until midnight EST Friday night for
     GAZ010.
NC...Winter Weather Advisory until midnight EST Friday night for
     NCZ508-510.
     Winter Storm Warning until midnight EST Friday night for
     NCZ033-035>037-048>050-052-053-056-057-059-062>065-
     501>507-509.
     Winter Weather Advisory below 3500 feet until midnight EST
     Friday night for NCZ051-058.
     Winter Storm Warning above 3500 feet until midnight EST Friday
     night for NCZ051-058.
     Winter Weather Advisory from 1 AM Friday to midnight EST
     Friday night for NCZ068>072.
SC...Winter Weather Advisory until midnight EST Friday night for
     SCZ001>003.

&&

SYNOPSIS...DEO
NEAR TERM...HG/JDL
SHORT TERM...Munroe
LONG TERM...Munroe
AVIATION...HG/JDL

Hazardous Weather Outlook
National Weather Service Greenville-Spartanburg SC
344 PM EST Thu Jan 7 2021

GAZ018-026-028-029-NCZ082-SCZ004>014-019-082045-
Stephens-Franklin-Hart-Elbert-Union NC-Greater Oconee-
Greater Pickens-Greater Greenville-Spartanburg-Cherokee-York-
Anderson-Abbeville-Laurens-Union SC-Chester-Greenwood-
344 PM EST Thu Jan 7 2021

This Hazardous Weather Outlook is for northeast Georgia, Union County
in the Piedmont of western North Carolina and Upstate South
Carolina.

.DAY ONE...This afternoon and tonight.

A strong low pressure system will move into the area tonight. Chilly
temperatures across the region could support wintry precipitation as
far south as the Interstate 85 corridor. Uncertainty is high with
this system, but there is the potential for some impact from wintry
weather late tonight. Continue to monitor the latest forecasts.

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

Wintry precipitation may result in some impacts Friday morning
before temperatures warm enough to transition the precipitation to
all rain.

.SPOTTER INFORMATION STATEMENT...

None.

NCZ051-058-082045-
Swain-Graham-
344 PM EST Thu Jan 7 2021

...WINTER STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO MIDNIGHT
EST FRIDAY NIGHT ABOVE 3500 FEET...
...WINTER WEATHER ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO
MIDNIGHT EST FRIDAY NIGHT BELOW 3500 FEET...

This Hazardous Weather Outlook is for Swain and Graham Counties in
western North Carolina.

.DAY ONE...This afternoon and tonight.

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

   Winter Weather Advisory.
   Winter Storm Warning.

.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 Weather Advisory.
   Winter Storm Warning.

.SPOTTER INFORMATION STATEMENT...

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

GAZ017-NCZ508-510-SCZ001>003-082045-
Habersham-Greater Rutherford-Eastern Polk-Oconee Mountains-
Pickens Mountains-Greenville Mountains-
344 PM EST Thu Jan 7 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO
MIDNIGHT EST FRIDAY NIGHT...

This Hazardous Weather Outlook is for Habersham County in northeast
Georgia, portions of the mountains of western North Carolina, and the
mountains of Upstate South Carolina.

.DAY ONE...This afternoon and tonight.

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

   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 Weather Advisory.

.SPOTTER INFORMATION STATEMENT...

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

GAZ010-NCZ033-035>037-048>050-052-053-056-057-059-062>065-501>507-
509-082045-
Rabun-Avery-Alexander-Iredell-Davie-Madison-Yancey-Mitchell-Haywood-
Buncombe-Catawba-Rowan-Northern Jackson-Macon-Southern Jackson-
Transylvania-Henderson-Caldwell Mountains-Greater Caldwell-
Burke Mountains-Greater Burke-McDowell Mountains-Eastern McDowell-
Rutherford Mountains-Polk Mountains-
344 PM EST Thu Jan 7 2021

...WINTER STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO MIDNIGHT
EST FRIDAY NIGHT...

This Hazardous Weather Outlook is for Rabun County in northeast
Georgia, as well as the mountains, northern foothills and northwest
Piedmont of western North Carolina.

.DAY ONE...This afternoon and 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.

.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.

.SPOTTER INFORMATION STATEMENT...

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

NCZ068>072-082045-
Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-
344 PM EST Thu Jan 7 2021

...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM FRIDAY TO MIDNIGHT
EST FRIDAY NIGHT...

This Hazardous Weather Outlook is for the Piedmont of western North
Carolina, including the Charlotte Metro Area.

.DAY ONE...This afternoon and tonight.

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

   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 Weather Advisory.

.SPOTTER INFORMATION STATEMENT...

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

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
421 PM EST Thu Jan 7 2021

GAZ018-026-028-029-SCZ004>008-010>013-019-080300-
Stephens-Franklin-Hart-Elbert-Greater Oconee-Greater Pickens-
Greater Greenville-Spartanburg-Cherokee-Anderson-Abbeville-
Laurens-Union SC-Greenwood-
Including the cities of Boydville, Toccoa, Royston, Gumlog,
Lavonia, Franklin Springs, Canon, Hartwell, Nuberg, Reed Creek,
Elberton, Fortsonia, Middleton, Ruckersville, Seneca, Oakway,
Easley, Dacusville, Clemson, Greenville, Taylors, Greer, Mauldin,
Fork Shoals, Simpsonville, Berea, Spartanburg, Gaffney, Anderson,
Abbeville, Calhoun Falls, Laurens, Clinton, Union, Monarch Mills,
Ware Shoals, and Ninety Six
421 PM EST Thu Jan 7 2021

...RAIN WITH MIXED WINTRY PRECIPITATION WILL SPREAD OVER NORTHEAST
GEORGIA AND UPSTATE SOUTH CAROLINA THIS EVENING...

A large shield of light to moderate rainfall will spread up the
Interstate 85 corridor from the southwest this evening. While the
precipitation will fall mainly as rain, snow and sleet will be
observed from time to time during the heaviest precipitation. With
temperatures mainly in the upper 30s, no accumulations are
currently expected on the ground, but slush could develop on some
elevated surfaces.

HG

Special Weather Statement
National Weather Service Greenville-Spartanburg SC
755 PM EST Thu Jan 7 2021

NCZ068>072-082-508-510-SCZ009-014-080500-
Cleveland-Lincoln-Gaston-Mecklenburg-Cabarrus-Union NC-
Greater Rutherford-Eastern Polk-York-Chester-
Including the cities of Shelby, Kings Mountain, Lincolnton,
Crouse, Gastonia, Charlotte, Huntersville, Matthews, Concord,
Kannapolis, Monroe, Trinity, Indian Trail, Weddington,
Forest City, Rutherfordton, Spindale, Tryon, Columbus,
Mill Spring, Catawba, Rock Hill, Blackstock, Chester, Cornwell,
and Great Falls
755 PM EST Thu Jan 7 2021

...RAIN MIXED WITH WINTRY PRECIPITATION WILL SPREAD OVER THE
EASTERN UPSTATE OF SOUTH CAROLINA AND THE CHARLOTTE METRO AREA
THROUGH LATE EVENING...

A large shield of light to moderate rainfall will spread across
the I-77 corridor in the Piedmont of the Carolinas, and also
across the southern foothills of western North Carolina, from the
southwest through late evening. While the precipitation will fall
mainly as rain, snow and sleet will be observed during the
heaviest precipitation. With temperatures mainly in the upper 30s,
no accumulations are currently expected on the ground, but slush
could develop on some elevated surfaces.

HG