920 
FXUS62 KFFC 302333
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
633 PM EST Fri Dec 30 2022



...New 00Z Aviation Discussion...

.SHORT TERM...
(This afternoon through Saturday)
Issued at 238 PM EST Fri Dec 30 2022

At the time of this writing, a broad mid level ridge is centered 
over the western Atlantic as a longwave trough extends southward 
from the northern High Plains into west Texas. Pronounced 
southwesterly flow aloft has set up between these two features, 
including the Southeast CONUS. Atmospheric moisture will steadily 
increase across north and central Georgia through the remainder of 
the day and into Saturday as the area remains under this 
southwesterly flow regime. Dewpoints primarily in the low 50s this 
afternoon are expected to increase into the upper 50s to low 60s by 
Saturday afternoon. Likewise, precipitable water values of around 
0.5" per the 12Z sounding will steadily rise to between 1.0" in far 
north Georgia to 1.5" in central Georgia by tomorrow afternoon. 

A wedge of high pressure developed over northeast Georgia this 
morning, and has expanded to cover much of the northern part of the 
state. Light rain falling over northeast Georgia this morning also 
allowed the wedge to strengthen its hold over the area. As such, low 
cloud ceilings remain in place across much of north Georgia, which 
has limited diurnal heating in this area. Afternoon highs today are 
expected to range from the upper 50s to mid 60s in north Georgia and 
increase into the low 70s in central Georgia. In the northeastern 
corner of the forecast area, where the influence of the wedge is 
strongest, these highs will be 5-10 degrees above average. Elsewhere 
across the area, the afternoon highs will be 10-15 degrees above 
average.

The axis of the trough will translate northeastward overnight and 
into the daytime Saturday. A cold front associated with the trough 
is expected to stretch from the Midwest into west Tennessee, and 
gradually push southeastward towards Georgia overnight into 
Saturday. Several shortwave disturbances will traverse the 
southwesterly mid-level flow ahead of this trough axis, which will 
help organize light to moderate showers ahead of the front during 
this timeframe. A surface low has begun to develop over the northern 
Gulf near the Mississippi Gulf coast, and is progged to move 
eastward roughly along the coast during the overnight hours. This 
should keep stronger surface-based instability to the south of the 
forecast area and mainly confined along the coast. While PoPs will 
be likely to categorical across much of the area overnight, there 
will only be a slight chance of thunderstorms in central Georgia 
through sunrise.

During the daytime on Saturday, the surface low moving along the 
coast will lift northeastward through eastern Alabama and north 
Georgia as the main cold front begins to push into the forecast 
area. With a moistening airmass and temperatures increasing into the 
mid 60s to low 70s, SBCAPE values are forecast to rise to around 500-
800 J/kg, at which point chances for thunderstorms will increase. 
Meanwhile, 0-1 km shear values will range from 25-30kt and deep 
layer bulk shear values will range from 50-60kt over central and 
east Georgia (mainly along and south of the I-85 corridor) during 
the daytime. The combination of these factors will contribute to a 
chance for a few thunderstorms to become strong to severe. Any 
severe thunderstorms that develop will be capable of producing 
damaging wind gusts. A brief tornado also cannot be ruled out. 
Rainfall totals from this system are forecast to be generally less 
than 1", but locally heavy rainfall will be possible with stronger 
storms that develop. 

The cold front will push southeastward out of the forecast area 
Saturday night into Sunday morning, with rain chances quickly coming 
to an end after midnight. As the trough axis clears Georgia to the 
east early Sunday morning, nearly zonal upper level flow will set up 
over the region as the long term period picks up.

King

&&

.LONG TERM...
(Sunday morning through next Thursday)
Issued at 238 PM EST Fri Dec 30 2022

The long term forecast starts off quiet as the trough lifts the cold 
front off to the northeast allowing for mostly sunny skies to 
prevail. A brief shot of dry air will infiltrate the forecast area 
with dewpoints in the upper 40s to 50s through much of Monday. 
Temperatures, however, will remain quite warm with forecast maximums 
topping out in the 60s and 70s. These warm surface temperatures will 
act to prime the atmosphere ahead of the next weather system that 
will impact the southeast midweek. A cut off low is expected to 
eject out of the Rockies over the central Plains and swing a 
negatively tilted trough across the central CONUS bringing the 
threat for hazardous weather to the forecast area as early as 
Tuesday evening. Several ingredients will be in place for concerns 
over thunderstorms becoming strong to severe. Plentiful moisture 
from the Gulf will raise dewpoints into the 60s, abundant bulk shear 
from 40 to 60kt will be present, and sufficient instability will be 
in place (SBCAPE and MUCAPE progged between 500 and 1000 J/kg along 
and north of I-20 where areas south reach up to 1500+ J/kg). Some 
uncertainty still remains over the severe potential as discrepancies 
amongst model guidance exists over trough amplification/tilt 
orientation, where the center of low pressure will track, and the 
timing of the front. The way these details play out will have a 
critical role over the dynamics/available instability for severe 
storms. Will continue to monitor the severe weather threat for this 
system as the forecast evolves over the next several days. Despite 
uncertainties in the extended forecast, there is increasing 
confidence that this system will produce some flooding concerns area 
wide. Regardless of exact timing, the front will slow down as it 
enters the CWA. Though current QPF has backed off some from previous 
forecasts, PWATs from 1.3-1.6" will overspread north and central 
Georgia and produce periods of heavy rainfall. QPF is progged to 
range from 2.5-4.5" with locally higher amounts possible in the 
north Georgia mountains. Temperatures will remain 10 to 15 degrees 
above average until the cold front finally pushes through Georgia at 
the end of the period, where they will moderate back to more 
seasonable values.

KAL

&&

.AVIATION...
(00Z TAFS)
Issued at 624 PM EST Fri Dec 30 2022

VFR across all terminals this evening ahead of a cold front and 
SHRA progged to move through the area overnight and into tomorrow.
As the system approaches the area CIGs will begin to lower 
overnight to MVFR around 03Z followed by IFR by 12Z. Tomorrow 
afternoon dynamics seem strong enough that thunder could be a 
possibility. Have used a PROB30 for TSRA around 18Z. Winds will 
remain E-SE at 5-10 kts.

//ATL Confidence...Avi Update...
Medium on all elements. 

28

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          52  64  49  66 /  90  80  30   0 
Atlanta         54  65  50  66 /  80  70  20   0 
Blairsville     50  60  44  63 /  90  80  40   0 
Cartersville    54  66  48  66 /  80  70  20   0 
Columbus        58  71  53  69 /  90  60  10   0 
Gainesville     51  61  47  65 /  80  80  30   0 
Macon           57  71  53  71 /  80  70  20   0 
Rome            56  66  49  66 /  90  70  20   0 
Peachtree City  54  67  50  67 /  90  70  20   0 
Vidalia         58  72  59  73 /  40  80  40   0 

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...King
LONG TERM....KAL
AVIATION...28