Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion
National Weather Service Peachtree City GA
1245 PM EST Thu Dec 30 2021

...18Z Aviation Forecast Discussion...

.PREV DISCUSSION... /Issued 901 AM EST Thu Dec 30 2021/

UPDATE...

Given training of heavy rainfall across areas centered on metro
Atlanta and a couple of tiers of counties north and south, a Flood
Watch has been issued through 00z. Rainfall totals have already
exceeded 2-3" in parts of the watch area overnight into this
morning, and additional heavier rainfall amounts could lead to
localized flooding concerns. This line of heavier convection is
expected to slowly sag southward through the next few hours with
heavier rainfall then tapering off across these areas. An isolated
severe risk also remains given strong wind fields aloft and
increasing instability from this morning into the afternoon.

RW

PREV DISCUSSION... /Issued 657 AM EST Thu Dec 30 2021/

UPDATE...

Updated for the 12Z Aviation Discussion.

PREV DISCUSSION... /Issued 513 AM EST Thu Dec 30 2021/

Update for cancellation of Tornado Watch 571...

UPDATE...

The overall severe threat has become more limited this morning as
cooler air surges southward and cuts off surface-rooted convection
across central portions of the CWA. Environmental parameters in
place still show at least an isolated threat for gusty winds,
small hail, and an outside chance for a weak tornado through the
late morning but  odds are too low to justify the continuation of
the Tornado Watch at this time. Warm, moist air overrunning the
outflow should continue south of the I-20 corridor,producing rain
rates around 1-2 in/hr in areas that have already seen 1-2 inches
of rainfall thus increasing the likelihood of isolated flash
flooding where training occurs.

Thiem

PREV DISCUSSION... /Issued 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...
18Z Update...
A large area of shra and tsra extends across ATL area and AHN sites
with heaviest tsra activity having shifted south of these sites.
Expect shra to persist at ATL/AHN sites through around 20-22Z
before tapering. Shra/tsra coverage will be on the increase at
MCN/CSG this afternoon into early evening before shifting south
after 00Z. Cigs are a mixed bag, ranging from IFR to VFR.
Generally expect lingering IFR and MVFR to lift toward VFR by
21-23Z before a rapid deterioration tonight, especially by 06Z
when IFR and LIFR cigs are expected along with areas of fog. Winds
remain SW to W through the period at 4-10kts with higher gusts
possible in tsra at MCN/CSG.

//ATL Confidence...18Z Update...
High confidence on winds.
Low to medium confidence on other elements.

RW

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          72  57  71  63 / 100  20  40  30
Atlanta         72  59  72  64 / 100  20  30  30
Blairsville     68  50  69  59 /  50  10  40  60
Cartersville    72  56  72  63 /  80  10  40  60
Columbus        77  63  77  66 /  60  30  30  20
Gainesville     71  57  69  63 /  80  20  40  60
Macon           78  62  77  65 /  60  40  30  20
Rome            72  56  72  64 /  60  10  40  60
Peachtree City  73  58  74  64 /  90  20  30  30
Vidalia         79  66  79  66 /  30  30  20  10

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 PM EST this evening for the following zones:
Banks...Barrow...Bartow...Butts...Carroll...Cherokee...Clarke...
Clayton...Cobb...Coweta...DeKalb...Douglas...Fayette...Floyd...
Forsyth...Greene...Gwinnett...Hall...Haralson...Heard...Henry...
Jackson...Jasper...Madison...Meriwether...Morgan...Newton...
North Fulton...Oconee...Oglethorpe...Paulding...Pike...Polk...
Putnam...Rockdale...South Fulton...Spalding...Taliaferro...
Troup...Walton...Wilkes.

&&

SHORT TERM...RW
LONG TERM....Lusk
AVIATION...RW

Hazardous Weather Outlook
National Weather Service Peachtree City GA
908 AM EST Thu Dec 30 2021

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-311415-
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-
908 AM EST Thu Dec 30 2021

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

.DAY ONE...Today and Tonight...

Thunderstorms will be possible across north and central Georgia
through this evening. The primary threats will be heavy rainfall, gusty
to damaging winds, a brief tornado, and cloud-to-ground
lightning. A Flood Watch is in effect until 7 PM for portions of
north Georgia, generally for areas along the Interstate 20
corridor.

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

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

Additional rounds of thunderstorms are possible Saturday and
Sunday. Some of these storms 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
1246 PM EST Thu Dec 30 2021

GAZ050-051-060-061-301815-
Taliaferro GA-Putnam GA-Hancock GA-Greene GA-
1246 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of Putnam, central
Hancock, southeastern Greene and southwestern Taliaferro Counties
through 115 PM EST...

At 1246 PM EST, a strong thunderstorm was over Warfield, or over
Eatonton, moving east at 45 mph.

HAZARD...40 to 50 mph wind, up to penny sized hail, frequent cloud
         to ground lightning and heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

Locations impacted include...
Eatonton, Sparta, White Plains, Phoenix, Reynolds at Lake Oconee,
Liberty, Springfield, Rockville, Shoulderbone, Oconee Springs Park,
Warfield and Willard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. If you can hear
thunder, you are close enough to be struck by lightning. Motorists
should slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 3321 8349 3336 8352 3350 8294 3323 8288
TIME...MOT...LOC 1746Z 259DEG 40KT 3329 8342

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

Special Weather Statement
National Weather Service Peachtree City GA
1248 PM EST Thu Dec 30 2021

GAZ050-051-060-061-301815-
Taliaferro GA-Putnam GA-Hancock GA-Greene GA-
1248 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of Putnam, central
Hancock, southeastern Greene and southwestern Taliaferro Counties
through 115 PM EST...

At 1248 PM EST, a strong thunderstorm was over Warfield, or over
Eatonton, moving east at 45 mph.

HAZARD...40 mph wind and heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

Locations impacted include...
Eatonton, Sparta, White Plains, Phoenix, Reynolds at Lake Oconee,
Liberty, Springfield, Rockville, Shoulderbone, Oconee Springs Park,
Warfield and Willard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. Motorists should
slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 3321 8349 3336 8352 3350 8294 3323 8288
TIME...MOT...LOC 1748Z 259DEG 40KT 3330 8339

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

Special Weather Statement
National Weather Service Peachtree City GA
1254 PM EST Thu Dec 30 2021

GAZ108>110-301830-
Telfair GA-Wilcox GA-Dodge GA-
1254 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of southeastern Dodge,
northwestern Telfair and east central Wilcox Counties through 130 PM
EST...

At 1254 PM EST, a strong thunderstorm was over Rhine, or near
Abbeville, moving northeast at 30 mph.

HAZARD...40 mph wind and heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

Locations impacted include...
Abbeville, Milan, Rhine, Chauncey and Browning.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. Motorists should
slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 3191 8330 3197 8333 3212 8305 3207 8294
      3196 8300
TIME...MOT...LOC 1754Z 247DEG 27KT 3197 8322

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

Special Weather Statement
National Weather Service Peachtree City GA
1254 PM EST Thu Dec 30 2021

GAZ108>110-301830-
Telfair GA-Wilcox GA-Dodge GA-
1254 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of southeastern Dodge,
northwestern Telfair and east central Wilcox Counties through 130 PM
EST...

At 1254 PM EST, a strong thunderstorm was over Rhine, or near
Abbeville, moving northeast at 30 mph.

HAZARD...40 mph wind and heavy rain.

SOURCE...Radar indicated.

IMPACT...Expect minor damage to tree limbs and blowing around of
         light, unsecured objects. Heavy rain may cause temporary
         street flooding especially in poor drainage areas.

Locations impacted include...
Abbeville, Milan, Rhine, Chauncey and Browning.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately. Motorists should
slow down and be prepared for possible loss of control due to
hydroplaning.

&&

LAT...LON 3191 8330 3197 8333 3212 8305 3207 8294
      3196 8300
TIME...MOT...LOC 1754Z 247DEG 27KT 3197 8322

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

Special Weather Statement
National Weather Service Peachtree City GA
113 PM EST Thu Dec 30 2021

GAZ066-067-078-301845-
Harris GA-Troup GA-Meriwether GA-
113 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of southwestern
Meriwether, southeastern Troup and northeastern Harris Counties
through 145 PM EST...

At 112 PM EST, National Weather Service doppler radar indicated a
strong thunderstorms over Jones Crossroads, or 9 miles northwest of
Hamilton, moving northeast at 30 mph.

HAZARD...Increased chance of a brief tornado.

SOURCE...Radar indicated.

IMPACT...This storm has exhibited localized rotation. A brief
         tornado could quickly form.

Locations impacted include...
Pine Mountain, F.d. Roosevelt State Park, Stovall, Big Springs,
Durand, Jones Crossroads, Baughs Crossroads, Odessadale and
Whitesville-Pine Lake.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately.

&&

LAT...LON 3278 8505 3285 8510 3308 8483 3285 8469
TIME...MOT...LOC 1812Z 244DEG 25KT 3285 8500

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

Special Weather Statement
National Weather Service Peachtree City GA
202 PM EST Thu Dec 30 2021

GAZ111>113-301930-
Toombs GA-Wheeler GA-Montgomery GA-
202 PM EST Thu Dec 30 2021

...A strong thunderstorm will impact portions of west central Toombs,
southeastern Wheeler and central Montgomery Counties through 230 PM
EST...

At 202 PM EST, National Weather Service doppler radar indicated a
strong thunderstorm near Jordan, or 9 miles south of Mount Vernon,
moving east at 30 mph.

HAZARD...40 to 50 mph wind and increased chance of a brief tornado.

SOURCE...Radar indicated.

IMPACT...While winds should result in minor damage to tree limbs and
         blowing around of light, unsecured objects, this storm has
         also exhibited localized rotation. A brief tornado could
         quickly form.

Locations impacted include...
Mount Vernon, Vidalia, Uvalda, Ailey, Higgston, Alston, South
Thompson, Center, Rock Springs and Charlotteville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People outdoors should seek shelter immediately.

&&

LAT...LON 3199 8265 3213 8270 3224 8240 3213 8231
      3203 8238
TIME...MOT...LOC 1902Z 248DEG 25KT 3205 8261

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH