Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion
National Weather Service Peachtree City GA
426 AM EST Thu Dec 30 2021

...Morning Area Forecast Discussion...

.SHORT TERM /Today through Friday/...

As has been the case for the last few days, upper ridging remains
centered over the Caribbean and extending roughly along the Atlantic
coast, and troughing remains in place over the western CONUS. This
persistent setup is keeping southwesterly upper level flow in place
over much of the eastern CONUS. At the surface, a stationary front
remains stalled to our north and stretching across the Tennessee
Valley. A strong surface high to the east of the Florida peninsula
is also maintaining southerly to southwesterly winds over Georgia.
As a result of these factors, north and central Georgia remains
within an unseasonably warm and moist airmass as the period begins.
Low temperatures this morning are expected to range from the low 60s
across far north Georgia to the upper 60s in east-central Georgia,
which will be between 28-32 degrees above climatological normals for
this time of the year. Perhaps "unseasonably warm" is a bit of an
understatement, as these lows could once again be near or above
records across the forecast area, once again.

Showers and thunderstorms are ongoing across portions of north
Georgia, roughly along and north of a line from Heard county to
Wilkes county. As the upper level shortwave traversing the upper
level flow and moving through the Tennessee Valley has moved
northeastward away from the forecast area, the line of showers and
thunderstorms has stalled across this area. Although minimal
instability remains across much of north Georgia, 0-1 km shear
values are still between 25-30 kts and deep layer bulk shear values
are between 50-60 kts. Although the marginal instability and the
lack of organized forcing are serving as limiting factors, it is
still possible that isolated stronger storms that develop this
morning could produce gusty and potentially damaging winds. With
deep moisture in place and precipitable values in excess of 1.5
inches across north Georgia, it is possible that stronger storms
could produce heavy rainfall. Localized flooding concerns are
therefore possible this morning, especially where training bands of
storms are able to set up.

The outlook for the daytime today remains a bit messy, and will be
contingent upon the evolution of the convection this morning and
where boundaries are able to set up in order to generate
convergence. Hi-res guidance continues to hint at the possibility of
a broken line of showers and thunderstorms pushing slowly southward
towards central Georgia late this morning and into the afternoon
hours, However, with non-existent synoptic scale forcing, there is
still much disagreement between model solutions on the timing and
evolution. In any case, high temperatures in the 70s and dewpoints
in the mid 60s will allow for sufficient instability for storm
maintenance, especially in central Georgia, where MUCAPE values
could range from 1200-1800 J/kg by this afternoon. Strong winds of
over 50 kts at 500 mb will also contribute to strong deep-layer bulk
shear co-located with the best instability. The combination of these
factors should be sufficient to support the development of a few
strong to severe thunderstorms. At this time, damaging wind gusts
appear to be the main threat with any severe storms that are able to
develop, as precipitation loading of downdrafts in stronger storms
could help transfer down the strong upper level winds. With low-
level shear values of 20-25 kts and 0-1 km SRH values of 100-150
m2/s2 in central Georgia, a brief tornado also cannot be ruled out,
as well. Aside from the lack of an organized forcing mechanism,
another limiting factor will be poor low and mid-level lapse rates.
As a result of these limitations, the SPC has kept the majority of
north and central Georgia in a Marginal Risk for severe weather in
their Day 1 outlook.

Storm total rainfall amounts throughout the remainder of the day are
currently forecast to be between 1-2 inches roughly along and south
of the I-20 corridor with progressively diminishing amounts to the
south. Given the aforementioned PWAT values over 1.5 inches,
stronger thunderstorms that develop could also produce locally
heavier rainfall. Fairly dry antecedent conditions remain in place
across central Georgia, which should help inhibit flooding concerns
in that area except for the possibility of heavy rain training over
a common location. On the other hand, observed rainfall in north
Georgia could increase the likelihood of flooding in areas that
receive additional heavy rain. In north Georgia, a couple of rivers
have moved to Minor Flood stage, with a handful of others near
bankfull.

Rain chances will steadily diminish this evening and tonight with
the loss of diurnal instability. With weak winds overnight and
saturated soils in locations that receive precipitation, it is
likely to see the development of fog across north and central
Georgia. The potential for dense fog development will furthermore
need to be monitored. The break from the rain during the overnight
hours into early Friday morning will be short-lived. As a surface
low strengthens over the Four Corners region and moves quickly
northeastward towards the Great Lakes region, another round of warm,
moist air will surge into the southeastern CONUS. Chances for
showers and thunderstorms will increase during the daytime on
Friday, with likely PoPs anticipated across north Georgia during the
afternoon hours. Modest instability, with SBCAPE values between 400-
800 J/kg, is possible in north Georgia in the afternoon. Deep layer
bulk shear values of 50+ kts and 0-1 km shear values of 20-25 kts
across the same location could lend itself to the possibility of
isolated severe thunderstorms capable of producing strong wind
gusts during the afternoon.

Considering the tropical airmass in place, both high and low
temperatures could match or exceed daily records through the short
term period, with lows in the 60s and highs in the 70s, and even
approaching the 80s in the far southern portions of the forecast
area.

King

.LONG TERM /Friday Night through Wednesday/...

Looks like the new year may be headed in with a bit of a bang still.
Long term picks up Friday night, where shortwave over Ontario
rotating within the Arctic branch of the jet will have weak sfc low
to the north of the CWA over Ohio River Valley. Strong, Arctic high
and associated Arctic airmass will be sliding down the Rockies into
the Great Plains thanks to strong confluence aloft with the
leading edge stalling out over the central Great Plains. Southerly
to southwesterly flow will be in place across the CWA at the sfc
in part as a mass response to sfc low to the north, leading to
additional WAA and isentropic lift that will act both to keep our
warm, moist airmass locked in place and bring some chances of
showers and thunderstorms, especially across north GA, though
upper level forcing will certainly be lacking for anything more
than a low end severe threat and instability is somewhat lacking.

All of this will set the stage for Saturday. Two shortwaves will be
rotating through the base of the long wave trough positioned out
west that will also finally be getting a boot as rossby wave
breaking deteriorates the blocking high over the east Pacific. The
first of these will be a cut-off low that merges on Friday with
the larger trough and then ejects into the Plains on Saturday.
Sfc low pressure forms and moves along baroclinic/frontal zone
established by aforementioned system above. This begins the
process of driving the cold front towards the CWA.

It is at this point where things get interesting with regard to
model spread. Through the week we have been emphasizing how models
have handled the ejection of the second shortwave/PV anomaly within
the larger trough. The details of this have LARGE implications on
the overall timing of the cold front, the chances of seeing severe
weather in the area, and what, if any, winter wx may happen on the
backside of the system. Today the models of swung again toward
having a less phased solution of these systems. What this means is
that as the larger upper level wave progresses east, it pushes the
cold front toward the area, but not as quickly as it would if these
waves were in phase. With the lagging shortwave/bowling ball of PV
moving in a little bit later, we see another sfc low able to form
just to the north of the CWA along the front and move to the NE on
Sunday. The results of this are a delay of the cold front really
moving through the area until Sunday, potential for some severe wx
on Sunday in parts of central and east central GA, possibly in
addition to some initial severe wx on Saturday with the initial
frontal surge, and the possibility of some winter wx in the
mountains and parts of north GA on the backside of all of the Sunday
evening into early overnight.

As stated in previous AFDs, there will be some potent ingredients in
place, and we will finally be getting the upper level support that
has been lacking for other severe wx days this week. With models
still jumping around with the potential timing of everything, it's
hard to truly pin down an exact timing, but late Saturday still
shows the most consistent potential for having severe wx. The other
aspect of this will be the flooding potential, and we are already
seeing some heavy rainfall across parts of north GA this morning
that will only increase the potential by priming many of our rivers
and saturating soils. QPF values remain in the 1.5"-2.5" range
across north GA and isolated higher amounts will certainly be
possible. Isolated flash flooding and some flooding of creeks,
streams, and rivers seems likely.

After this, we finally get cold air into the CWA. The formation of a
sfc low may kick some snow showers back into north GA and especially
the mountains, though accumulations still don't seem likely at this
time. Track of the low would just be a bit too far north for
anything too significant in terms of accumulations (if that
solutions even plays out). Overnight lows look to be in the 20s and
30s across the area on Sunday night. Cool airmass moves into place
for a few days under sfc high that slowly slides to the east.
Temperatures will slowly increase as airmass modifies and
winds slowly turn back south through the end of the forecast
period.

Lusk

&&

.CLIMATE...

Records for 12-30

               Max Temperature         Min Temperature
  Station      High        Low         High        Low
  -------  ----------  ----------  ----------  ----------
   KAHN      76 1984     28 1909     60 1969      9 1917
   KATL      73 1984     26 1880     60 1996      1 1880
   KCSG      80 1984     34 1983     61 2015     15 1961
   KMCN      78 1984     27 1917     66 2015     13 1917

Records for 12-31

               Max Temperature         Min Temperature
  Station      High        Low         High        Low
  -------  ----------  ----------  ----------  ----------
   KAHN      76 1984     24 1917     58 1996     13 1917
   KATL      73 1984     26 1917     61 1996      4 1880
   KCSG      81 1923     34 1917     62 1936     18 1983
   KMCN      79 1923     28 1917     61 1973     14 1983

Records for 01-01

               Max Temperature         Min Temperature
  Station      High        Low         High        Low
  -------  ----------  ----------  ----------  ----------
   KAHN      76 1985     31 1936     59 1985      6 1918
                1952
   KATL      75 1952     25 1928     57 2019      7 1928
                                        1985
                                        1952
   KCSG      78 1952     32 1918     63 2019     18 1977
   KMCN      78 1985     32 1928     65 2019     17 1984
                                                    1928
                                                    1918

Records for 01-02

               Max Temperature         Min Temperature
  Station      High        Low         High        Low
  -------  ----------  ----------  ----------  ----------
   KAHN      73 1952     26 1928     57 1966     11 2018
                1930
   KATL      73 1952     17 1928     56 1997      1 1928
   KCSG      79 1909     30 1928     61 1966     11 1928
   KMCN      78 1952     23 1928     61 2017      8 1928

&&

.AVIATION...
06Z Update...
A line of SHRA/TSRA is currently extending from roughly ATL to
AHN, and slowly pushing southeastward. This precip has warranted
prevailing SHRA and a TEMPO for TSRA and gusty winds at ATL and
AHN. Ceilings are mainly MVFR ahead of the line, with some IFR
mixed in. MVFR ceilings and SHRA/TSRA will prevail through the
morning and into the afternoon before brief improvement to VFR
and precip trailing off after 22Z. With moist soils and light
winds after Thursday night, IFR ceilings and fog are expected to
develop between 02-06Z. Aside from gusty winds with any
thunderstorms that occur, winds are expected to be SW at 7-11 kts
throughout the day before becoming W at 6 kts or less after 02Z.

//ATL Confidence...06Z Update...
High confidence on winds.
Low to medium confidence on all other elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          72  57  71  63 /  80  40  60  60
Atlanta         72  59  72  64 /  80  30  70  50
Blairsville     68  50  69  59 /  50  20  70  80
Cartersville    72  56  72  63 /  70  20  70  60
Columbus        77  63  77  66 /  60  40  60  30
Gainesville     71  57  69  63 /  70  30  70  70
Macon           78  62  77  65 /  60  50  50  20
Rome            72  56  72  64 /  60  20  70  60
Peachtree City  73  58  74  64 /  80  30  70  40
Vidalia         79  66  79  66 /  30  30  30   5

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Tornado Watch until 5 AM EST early this morning for the
following zones: Banks...Barrow...Butts...Carroll...Clarke...
Clayton...Coweta...DeKalb...Douglas...Fayette...Greene...
Gwinnett...Hall...Heard...Henry...Jackson...Jasper...Jones...
Lamar...Madison...Meriwether...Monroe...Morgan...Newton...North
Fulton...Oconee...Oglethorpe...Pike...Putnam...Rockdale...South
Fulton...Spalding...Troup...Walton.

&&

SHORT TERM...King
LONG TERM....Lusk
AVIATION...King

Hazardous Weather Outlook
National Weather Service Peachtree City GA
405 PM EST Wed Dec 29 2021

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-302115-
Baldwin-Banks-Barrow-Bartow-Bibb-Bleckley-Butts-Carroll-Catoosa-
Chattahoochee-Chattooga-Cherokee-Clarke-Clayton-Cobb-Coweta-
Crawford-Crisp-Dade-Dawson-DeKalb-Dodge-Dooly-Douglas-Emanuel-
Fannin-Fayette-Floyd-Forsyth-Gilmer-Glascock-Gordon-Greene-
Gwinnett-Hall-Hancock-Haralson-Harris-Heard-Henry-Houston-Jackson-
Jasper-Jefferson-Johnson-Jones-Lamar-Laurens-Lumpkin-Macon-
Madison-Marion-Meriwether-Monroe-Montgomery-Morgan-Murray-
Muscogee-Newton-North Fulton-Oconee-Oglethorpe-Paulding-Peach-
Pickens-Pike-Polk-Pulaski-Putnam-Rockdale-Schley-South Fulton-
Spalding-Stewart-Sumter-Talbot-Taliaferro-Taylor-Telfair-Toombs-
Towns-Treutlen-Troup-Twiggs-Union-Upson-Walker-Walton-Warren-
Washington-Webster-Wheeler-White-Whitfield-Wilcox-Wilkes-
Wilkinson-
405 PM EST Wed Dec 29 2021

This Hazardous Weather Outlook is for portions of North and Central Georgia.

.DAY ONE...Tonight...

Thunderstorms will be possible across north and central Georgia
the rest of the evening and into tonight. The primary threats
will be gusty to damaging winds, a brief tornado, periods of heavy
rain, and occasional cloud-to-ground lightning. Isolated flooding
will be possible where the heaviest rain occurs across north
Georgia.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday...

There is a chance for thunderstorms Thursday for north and
central Georgia. The primary threats will be gusty to damaging
winds, a brief tornado, periods of heavy rain, and occasional
cloud-to-ground lightning.

Additional rounds of thunderstorms are possible Friday, Saturday,
and Sunday. Some of the storms on Saturday may be severe. There is
also a possibility for some mixed wintry precipitation in far
northern Georgia overnight Sunday evening into early Monday
morning. Stay tuned to the latest forecasts throughout the week
for more details.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not requested but spotters are encouraged
to submit reports of severe weather through the web by going to
weather.gov/atlanta.  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 Peachtree City GA
100 AM EST Thu Dec 30 2021

GAZ033>038-044>047-055-300700-
North Fulton GA-Walton GA-Rockdale GA-Barrow GA-Clayton GA-DeKalb GA-
Gwinnett GA-Oglethorpe GA-Clarke GA-Oconee GA-South Fulton GA-
100 AM EST Thu Dec 30 2021

...Strong thunderstorms with very heavy rain will impact portions of
northeastern Rockdale, Oconee, southern Barrow, DeKalb, southern
Gwinnett, Clarke, Walton, southwestern Fulton, northern Clayton and
northern Oglethorpe Counties through 200 AM EST...

At 100 AM EST, a line of thunderstorms with very heavy rain was
along a line extending from Bowman to near Crawford to near Big
Haynes Creek Park, and moving east at 55 mph.

HAZARD...Heavy rain.

SOURCE...Radar indicated.

IMPACT...Heavy rain may cause temporary flooding especially in poor
         drainage areas.

Locations impacted include...
Atlanta, Lawrenceville, Decatur, Conyers, Winder, Monroe,
Watkinsville, Athens, East Point, Union City, Forest Park,
Snellville, College Park, Fairburn, Lilburn, Loganville, Clarkston,
Hapeville, Stone Mountain and Avondale Estates.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Motorists should slow down and be prepared for possible loss of
control due to hydroplaning.

A Tornado Watch remains in effect until 500 AM EST for north central
and northeastern Georgia.

&&

LAT...LON 3360 8479 3378 8453 3400 8374 3402 8356
      3397 8354 3404 8336 3400 8322 3405 8314
      3402 8305 3404 8298 3397 8278 3378 8347
      3382 8351 3377 8355 3370 8384 3374 8391
      3367 8395 3365 8428 3363 8426 3353 8481
TIME...MOT...LOC 0600Z 269DEG 47KT 3420 8300 3393 8316 3375 8400

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH

Special Weather Statement
National Weather Service Peachtree City GA
107 AM EST Thu Dec 30 2021

GAZ052-066-300630-
Troup GA-Heard GA-
107 AM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of Heard and northern
Troup Counties through 130 AM EST...

At 106 AM EST, a strong thunderstorm was near Rock Stand Alabama, or
8 miles west of Waresville, moving east at 50 mph.

HAZARD...40 to 50 mph wind, pea sized hail and frequent cloud to
         ground lightning.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects.

Locations impacted include...
Franklin, Hogansville, Corinth, Waresville, Texas, Harrisonville,
Glenn and Powers Crossroads.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning.

A Tornado Watch remains in effect until 500 AM EST for west central
Georgia.

&&

LAT...LON 3337 8499 3328 8496 3328 8495 3326 8495
      3322 8494 3314 8491 3315 8524 3331 8527
TIME...MOT...LOC 0606Z 266DEG 45KT 3321 8537

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

Special Weather Statement
National Weather Service Peachtree City GA
127 AM EST Thu Dec 30 2021

GAZ052-053-066-300700-
Coweta GA-Troup GA-Heard GA-
127 AM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of southern Heard,
northern Troup and southwestern Coweta Counties through 200 AM EST...

At 127 AM EST, a strong thunderstorm was over Texas, or near
Franklin, moving east at 35 mph.

HAZARD...Up to 40 mph wind, pea sized hail and frequent cloud to
         ground lightning.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects.

Locations impacted include...
Franklin, Hogansville, Grantville, Corinth, Texas, Harrisonville,
Hillcrest and Glenn.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning.

A Tornado Watch remains in effect until 500 AM EST for west central
Georgia.

&&

LAT...LON 3314 8521 3327 8522 3334 8494 3324 8484
      3312 8490
TIME...MOT...LOC 0627Z 263DEG 30KT 3321 8516

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
130 AM EST THU DEC 30 2021

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

1230 AM     TSTM WND DMG     2 SW FLOWERY BRANCH     34.17N  83.94W
12/30/2021                   HALL               GA   911 CALL CENTER

            SEVERAL TREES DOWN WITH REPORTS OF DAMAGE TO SOME HOMES
            AS A RESULT IN THE 6000 BLOCK OF GAINES FERRY RD.

&&

EVENT NUMBER FFC2100695

LUSK

Special Weather Statement
National Weather Service Peachtree City GA
232 AM EST Thu Dec 30 2021

GAZ037-046>050-300830-
Morgan GA-Walton GA-Rockdale GA-Greene GA-Oconee GA-Newton GA-
232 AM EST Thu Dec 30 2021

...Strong thunderstorms with very heavy rain will impact portions of
east central Rockdale, southeastern Oconee, central Morgan, southern
Walton, northwestern Greene and northeastern Newton Counties through
330 AM EST...

At 231 AM EST, a line of strong thunderstorms with very heavy rain
was along a line extending from Georgia International Horse Park to
near Farmington, and moving east at 50 mph.

HAZARD...Heavy rain.

SOURCE...Radar indicated.

IMPACT...Heavy rain may cause temporary flooding especially in poor
         drainage areas.

Locations impacted include...
Conyers, Covington, Madison, Social Circle, Oxford, Walnut Grove,
Rutledge, Bostwick, Jersey, Georgia International Horse Park,
Ebenezer, Wrayswood, Almon, Milstead, Hard Labor Creek State Park,
Greshamville, Brick Store, Herndonville, Gum Creek and Apalachee.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Motorists should slow down and be prepared for possible loss of
control due to hydroplaning.

A Tornado Watch remains in effect until 500 AM EST for north central,
northeastern and east central Georgia.

&&

LAT...LON 3357 8348 3363 8410 3375 8387 3378 8329
      3376 8328 3370 8312 3371 8305
TIME...MOT...LOC 0731Z 273DEG 44KT 3365 8394 3376 8337

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH

Special Weather Statement
National Weather Service Peachtree City GA
450 AM EST Thu Dec 30 2021

GAZ042>044-052>054-301030-
Fayette GA-Douglas GA-Coweta GA-Carroll GA-Heard GA-South Fulton GA-
450 AM EST Thu Dec 30 2021

...Strong thunderstorms will impact portions of Fayette, southern
Carroll, southwestern Douglas, Heard, Coweta and southwestern Fulton
Counties through 530 AM EST...

At 450 AM EST, a line of strong thunderstorms was along a line
extending from near Sandy Creek to Newell, and moving east at 15 mph.

HAZARD...Heavy rain.

SOURCE...Radar indicated.

IMPACT...Heavy rain may cause temporary street flooding especially
         in poor drainage areas.

Locations impacted include...
Newnan, Carrollton, Fayetteville, Franklin, Peachtree City, Union
City, College Park, Fairburn, Tyrone, Palmetto, Senoia, Grantville,
Bowdon, Whitesburg, Brooks, Ephesus, Centralhatchee, Moreland,
Sharpsburg and Turin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Motorists should slow down and be prepared for possible loss of
control due to hydroplaning.

A Tornado Watch remains in effect until 500 AM EST for north central,
northwestern and west central Georgia.

&&

LAT...LON 3363 8446 3355 8446 3355 8444 3350 8442
      3348 8439 3346 8438 3344 8440 3341 8439
      3336 8440 3332 8439 3326 8443 3322 8486
      3322 8494 3321 8497 3319 8525 3354 8531
TIME...MOT...LOC 0950Z 260DEG 13KT 3351 8452 3341 8539

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH