Special Weather Statement, NWS Atlanta, GA

Area Forecast Discussion
National Weather Service Peachtree City GA
801 PM EST Wed Dec 29 2021

.UPDATE...

Tornado watch remains in effect until 11PM across far NW GA.

The line of expected thunderstorms is currently in Alabama and is
still on track to move through the area late tonight into the
early morning hours of Thursday. Isolated tornadoes and strong
wind gusts continue to be possible with this activity with a focus
across NW GA. Otherwise, have updated PoPs to match the current
environment. Tomorrow, precip continues to look possible on and
off during the day, with CAMs consistently showing a cluster of
storms near the Metro area. However, how intense and where storms
will exactly develop will be dependent on the post storm
environment and where lingering boundaries settle.

.PREV DISCUSSION... /Issued 400 PM EST Wed Dec 29 2021/

.Afternoon Area Forecast Discussion...

SHORT TERM /Tonight through Thursday Night/...

A complicated and messy forecast characterizes the short term
period. Upper ridging remains situated to our southeast across the
Caribbean with troughing across the Western US. Meanwhile, at the
surface a stationary front remains stalled to our north stretching
from the mid-Mississippi Valley across the Tennessee Valley. Thus,
our region remains stuck within the persistent warm sector with
unseasonable heat continuing through the short term.

This afternoon, one lingering area of showers persists across
portions of central and eastern Georgia while another persistent
rain shield has been ongoing across portions of northern Alabama
into Tennessee. The primary focus going forward will be on the
potential for severe thunderstorms from late evening into the
overnight hours. An upper shortwave presently ejecting into the mid-
Mississippi Valley and its developing attendant surface low will
push rapidly northeastward into this evening.

The most favored scenario is for convection to continue initiating
ahead of this feature with clusters organizing perhaps into linear
features as they progress eastward into tonight. One question mark
at this point regarding this scenario pertains to the aforementioned
persistent rainfall shield situated across northern Alabama into
Middle Tennessee and its effect on limiting the environment ahead of
any developing convection. With that said, if sustained convection
is able to evolve as outlined, it will encounter strong wind fields
and elongated hodographs and up to 500 J/kg or so of SBCAPE,
favoring a damaging wind threat as well as the threat for a few
embedded brief tornadoes as well. CAMs have increasingly favored
this potential, indicating a line of convection racing into
northwest Georgia late this evening and progressing east-
southeastward toward the Atlanta metro around and after midnight.
SPC has highlighted an outlook upgrade to an Enhanced Risk for far
northwest Georgia and a Slight Risk for areas generally along and
northwest of I-85 with a Marginal Risk farther southeast for
Thursday morning. Additionally, given rainfall totals from this
morning locally over an inch across far north Georgia, any training
cells that potentially become established could lead to localized
flash flooding concerns overnight into Thursday morning.

The outlook for Thursday remains a bit murky and will depend to a
large extent on the evolution of the morning convection across north
Georgia. With the area still firmly situated within the warm sector
and no large-scale forcing mechanism in place, additional convective
development through the day on Thursday will depend on convergence
along lingering boundaries from morning convection. A strong LLJ
would provide some potential for severe, so it will bear watching on
Thursday.

Finally, forecast low temperatures and afternoon highs on Thursday
are near or above record levels yet again for the date.

RW

LONG TERM /Friday through Wednesday/...

By Friday, the current troublesome, muddied storm system should have
concluded across the forecast area as we begin setting up across the
Great Plains, Midwest, Southern, and Southeastern CONUS for the
next, much more robust system.

Friday and Friday night, a shortwave pivoting across south central
Canada opens the gates for cold arctic air to begin spilling into
the Northern and Central Plains, setting up a sharp frontal boundary
across northeast New Mexico, the Texas panhandle, and northern
Oklahoma. At the same time in the mid- to upper-levels, a stronger
shortwave will begin digging from the northern Rockies into the
Great Basin region as a cutoff low approaches from northern Baja
California. These two areas of lower pressure merge into a very
stout longwave trough through Friday night over the Four Corners
region. The positive vorticity advection from the approach of this
deep troughing towards the aforementioned baroclinic zone is expected
to result in strong, rapid surface cyclogenesis. The resulting low
pressure system will race off to the northeast and quickly begin
pulling further warm, moist air up from the Gulf of Mexico into the
Southeastern CONUS, as pulling down much colder air from the
northern Great Plains and southern Canada. Eventually the cold
airmass will surge through the forecast area from Saturday
afternoon through Sunday morning, but more on that in a second.

As incredibly warm air is pulled into Georgia temperatures will
continue be far above seasonal norms. In fact, afternoon highs,
capped slightly by dense considerable cloud cover will still remain
about 20 degrees above normal through Friday, with morning lows
boosted by a very moist airmass settling above 30 degrees above
seasonal norms through Saturday Night ahead of the cold frontal
system. It is inevitable that if the forecast is even close to on
track, several high minimum temperature records will be smashed,
with several other high temperature records likely to fall as well
ahead of the cold frontal system.

Warm, moist air surging into the region will also have the
opportunity to produce further rainfall and potential storms which
may become severe for portions of North Georgia on Friday ahead of
the frontal system. Currently a Marginal Risk is in effect for the
area with very divided model simulations resolving the possibility
for precip in Georgia and the surrounding areas. As it looks, we'll
have weak instability within the tropical airmass that's been
smothering the region, but will also have decent shear profiles
over the area as well. SBCAPE values are expected to range between
250-750 J/kg, not bad for this time of year, but combined with SFC-
500mb bulk shear values around 50kts and decent low-level
hodographs, there's a chance any storms that form could contain a
marginal severe or even tornadic threat. However, as it stands, it
remains to be seen if any storms will initiate at all. Higher
chances will exist further north, but several models still hint at a
dry forecast. Only time will tell.

Finally on Saturday, the surface low pressure will be dashing into
the Midwest ahead of the longwave trough quickly pivoting across the
Southern Plains. Rapid height falls in the Southern Plains and Lower
Mississippi River Valleys will force even further subsidence behind
the frontal system with a strong high pressure forming in that
region, helping to propel the cold front even faster as time goes
on. Models are coming into an agreement with the frontal passage
expected to move through the forecast area Saturday Night. With so
much surface forcing, and upper level support/dynamics, combined
with the warm, moist airmass already over the area, the potential
for severe weather will be elevated. a 15 percent outlook already
exists in SPCs Day 4 outlook for areas along and northwest of the I-
85 corridor, and unusual feat for this time of year to be sure. In
addition, another 1-2.5 inched of rain accumulations could be in
store, increasing chances for isolated flooding as well.

Following the frontal passage, temperatures will drop off quickly
with temperatures falling by 50 degrees from Saturday afternoon
through Monday morning, with highs and lows around 5-10 degrees
below normal by that time. With colder air finally flooding into the
forecast region another wrench in the forecast comes to light with
possible wintry precip mixed in behind the cold front in North
Georgia, as some models hint towards relatively moist air wrapping
back around the southern Appalachians along the warm, moist conveyor
belt if a local low pressure forms along the frontal zone in the Mid-
Atlantic states. However, other models have indicated cold, and dry
air pushing into the region more forcibly preventing any wintry mix
from falling. Again time will tell, but currently giving about a
50/50 chance of seeing at least some mixed rain /snow in north
Georgia. No accumulations are forecast at time time given split
probabilities, but if chances were to increase the most likely spots
of seeing anything more than flurries would be in the northeast
Georgia mountains. But given how warm the grounds are from this warm
pattern we've been in combined with wet surfaces and stronger winds
behind the front, I wouldn't expect anything to stick around if it
does fall!

Thiem

CLIMATE...

Records for 12-29

               Max Temperature         Min Temperature
  Station      High        Low         High        Low
  -------  ----------  ----------  ----------  ----------
   KAHN      79 1984     26 1909     62 2019     12 1925
   KATL      72 1984     29 1894     62 2019      4 1894
   KCSG      79 1984     38 1961     66 2019     20 1902
                1923
   KMCN      80 1984     37 1935     66 2015     17 1925

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

AVIATION...00Z Update...

Current VFR CIGs start to deteriorate to MVFR/IFR late this
evening as SHRA/TSRA moves through the terminals. Metro ATL and
AHN will likely see TSRA between 04Z-06Z with MCN/CSG generally
seeing SHRA through the period. Uncertainty remains regarding the
severity of the storms and the exact timing of the line moving
through the terminals. MVFR with SHRA/TSRA will likely prevail for
much of the day Thursday.

//ATL Confidence...00Z Update...
Medium confidence on all elements.

28

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          63  72  57  72 /  70  70  40  60
Atlanta         64  72  59  71 /  70  70  30  60
Blairsville     58  68  50  68 /  90  70  20  60
Cartersville    63  71  57  72 /  80  70  20  70
Columbus        66  76  63  77 /  40  70  40  40
Gainesville     63  70  57  70 /  70  80  30  70
Macon           65  78  62  77 /  20  50  40  40
Rome            63  73  57  72 /  80  70  20  70
Peachtree City  64  73  58  72 /  60  70  30  60
Vidalia         67  79  66  80 /  10  30  30  20

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Tornado Watch until 11 PM EST this evening for the following
zones: Chattooga...Dade...Floyd...Walker.

&&

SHORT TERM...28
LONG TERM....Thiem
AVIATION...28

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
1051 PM EST Wed Dec 29 2021

GAZ041-300415-
Haralson GA-
1051 PM EST Wed Dec 29 2021

...Strong thunderstorms will impact portions of Haralson County
through 1115 PM EST...

At 1051 PM EST, a line of strong thunderstorms was along a line
extending from near Esom Hill to Oak Level to Coleman Lake And
Campground, and moving east at 35 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...
Buchanan, Tallapoosa, Felton and Eubank Lake.

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 northwestern
Georgia.

&&

LAT...LON 3390 8522 3391 8521 3390 8504 3380 8507
      3372 8535 3390 8538
TIME...MOT...LOC 0351Z 272DEG 32KT 3390 8534 3383 8545 3379 8559

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1114 PM EST WED DEC 29 2021

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

0955 PM     TSTM WND DMG     1 W CENTER POST         34.60N  85.37W
12/29/2021                   WALKER             GA   EMERGENCY MNGR

            CHATTOOGA COUNTY EMERGENCY MANAGEMENT REPORTED A POWER
            LINE BLOWN DOWN AROUND THE INTERSECTION OF HARRISBURG
            ROAD AND BOLCAR BOULEVARD.

1005 PM     TSTM WND DMG     1 NE JAMES H. FLOYD STA 34.45N  85.32W
12/29/2021                   CHATTOOGA          GA   EMERGENCY MNGR

            THE CHATTOOGA COUNTY EMERGENCY MANAGER REPORTED A TREE
            BLOWN DOWN AROUND MARBLE SPRINGS ROAD AND SLOPPY FLOYD
            LAKE ROAD.

&&

EVENT NUMBER FFC2100693
EVENT NUMBER FFC2100694

20

Special Weather Statement
National Weather Service Peachtree City GA
1135 PM EST Wed Dec 29 2021

GAZ015-016-023-024-300500-
Hall GA-Banks GA-White GA-Lumpkin GA-
1135 PM EST Wed Dec 29 2021

...Strong thunderstorms will impact portions of southeastern Lumpkin,
Banks, White and Hall Counties through MIDNIGHT EST...

At 1135 PM EST, a line of strong thunderstorms was along a line
extending from near Sautee to near Dougherty, and moving east at 70
mph.

HAZARD...Up to 40 mph wind, 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...
Gainesville, Dahlonega, Cleveland, Homer, Oakwood, Lula, Maysville,
Clermont, Helen, Gillsville, Unicoi State Park, Robertstown,
Pinefield Crossroads, Mossy Creek, Murrayville, Garland, Leaf,
Smithgall Woods Conservation Are, Hollingsworth and Sautee.

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.

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

&&

LAT...LON 3473 8362 3465 8366 3455 8362 3451 8366
      3449 8366 3443 8361 3449 8354 3447 8342
      3439 8338 3426 8349 3426 8357 3429 8362
      3425 8367 3424 8395 3429 8393 3436 8398
      3442 8398 3446 8394 3449 8408 3478 8365
TIME...MOT...LOC 0435Z 270DEG 63KT 3471 8361 3441 8406

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

Special Weather Statement
National Weather Service Peachtree City GA
1142 PM EST Wed Dec 29 2021

GAZ023>025-032>035-045-300515-
Hall GA-Banks GA-Jackson GA-North Fulton GA-Barrow GA-Cobb GA-
DeKalb GA-Gwinnett GA-
1142 PM EST Wed Dec 29 2021

...Strong thunderstorms will impact portions of northwestern Barrow,
northwestern DeKalb, southern Cobb, Gwinnett, southwestern Banks,
southern Hall, northwestern Jackson and central Fulton Counties
through 1215 AM EST...

At 1142 PM EST, a line of strong thunderstorms was along a line
extending from near Cumming to near Johns Creek to near Hiram, and
moving east at 55 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...
Atlanta, Marietta, Gainesville, Lawrenceville, Decatur, Winder,
Jefferson, Sandy Springs, Roswell, Smyrna, Dunwoody, Duluth, Sugar
Hill, Suwanee, Buford, Lilburn, Chamblee, Norcross, Doraville and
Clarkston.

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 north central
and northeastern Georgia.

&&

LAT...LON 3430 8352 3405 8362 3377 8429 3378 8461
      3380 8462 3381 8471 3396 8438 3400 8422
      3406 8415 3405 8410 3407 8412 3415 8409
      3419 8405 3420 8399 3425 8395 3425 8367
      3429 8362
TIME...MOT...LOC 0442Z 270DEG 49KT 3424 8415 3406 8423 3385 8475

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

Special Weather Statement
National Weather Service Peachtree City GA
1148 PM EST Wed Dec 29 2021

GAZ033-042>044-300515-
North Fulton GA-Douglas GA-Carroll GA-South Fulton GA-
1148 PM EST Wed Dec 29 2021

...Strong thunderstorms will impact portions of central Carroll,
Douglas and central Fulton Counties through 1215 AM EST...

At 1148 PM EST, a line of strong thunderstorms was along a line
extending from near Brownsville to near the I-20 Welcome Center, and
moving east at 45 mph.

HAZARD...Up to 40 mph wind, 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...
Atlanta, Douglasville, Carrollton, Villa Rica, Austell, Temple, Mount
Zion, Lithia Springs, Grant Park-Zoo Atlanta, Sweet Auburn, Bill Arp,
Fairplay, Abilene, Winston, Lake Val-Do-Mar, John Tanner State Park,
Cascade Heights, Sandtown, Sweetwater Creek State Park and West End.

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.

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

&&

LAT...LON 3365 8529 3370 8514 3369 8512 3372 8505
      3374 8505 3378 8489 3379 8473 3381 8472
      3381 8462 3374 8458 3379 8452 3377 8435
      3374 8435 3354 8513 3358 8533 3365 8534
TIME...MOT...LOC 0448Z 278DEG 39KT 3381 8471 3364 8531

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

Special Weather Statement
National Weather Service Peachtree City GA
1203 AM EST Thu Dec 30 2021

GAZ023-024-300530-
Hall GA-Banks GA-
1203 AM EST Thu Dec 30 2021

...Strong thunderstorms will impact portions of Banks and
northeastern Hall Counties through 1230 AM EST...

At 1203 AM EST, a line of strong thunderstorms was along a line
extending from near Alto to Gillsville to near Candler, and moving
east at 45 mph.

HAZARD...Up to 40 mph wind, 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...
Gainesville, Homer, Lula, Maysville, Gillsville, Pinefield
Crossroads, Hollingsworth and Banks Crossing.

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.

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

&&

LAT...LON 3448 8346 3446 8340 3442 8338 3432 8339
      3426 8334 3422 8336 3420 8338 3420 8341
      3426 8348 3425 8356 3429 8362 3424 8369
      3425 8381 3433 8372 3449 8366 3443 8361
      3449 8354
TIME...MOT...LOC 0503Z 274DEG 41KT 3449 8359 3433 8365 3425 8375

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