690
FXUS62 KFFC 121047
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
647 AM EDT Wed Mar 12 2025

...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Thursday)
Issued at 511 AM EDT Wed Mar 12 2025

Key Messages:

    - Warm and dry today, then chances for showers and
      thunderstorms, some strong, return on Thursday

    - Fire Danger Statement in effect for portions of north and
      north central Georgia until 8PM

Over the course of the day today, the surface high pressure system
that has supported dry and mild conditions will be nudged eastward
out of the Gulf by a mid-level shortwave approaching from the west.

The combined effects of lingering (albeit exiting) subsidence under
the northern fringes of the surface high and continued dry,
quasi-zonal flow aloft will allow for another clear and warm day
areawide today. Fine fuels dried out quickly yesterday under fairly
strong afternoon mixing, even in locales that received more
substantial rainfall on Monday. Expecting dewpoints to plunge well
below base NBM guidance once again this afternoon based on trends
observed yesterday, so made use of NBM05 (5th percentile!) dewpoints
when crafting the forecast. Caveat being that there is still non-
zero potential that even the 5th percentile is a bit too moist.
Given minimum relative humidity values once again dipping down below
critical thresholds for high fire danger (sub-25 percent), have
issued another Fire Danger Statement for portions of north and north
central Georgia through 8PM.

As the aforementioned shortwave encroaches on the AL/GA border late
tonight/early Thursday, expect moisture recovery to begin in
earnest, setting the stage for a more active next several days.
Chances for showers and thunderstorms will increase beginning around
daybreak on Thursday, spreading west to east into the afternoon.
HiRes guidance progs as much as 1000-1250 J/kg of surface-based
instability to overspread much of north and central Georgia under
the influence of diurnal heating and dewpoints surging into the 50s
(compared to the 30s today). Kinematics are relatively weak --
approximately 20-30kts of effective shear -- given that our mid-
level forcing is fairly dilute, but expect there to be enough oomph
to support the develop of isolated multicell clusters capable of
producing damaging wind gusts and perhaps marginally severe hail at
peak intensity. A Marginal (level 1 out of 5) Risk is in effect for
portions of west central Georgia to highlight the right of a few
strong to severe storms.

Highs today will be several degrees warmer than yesterday, topping
out in the mid-to-upper 70s -- as much as 8-15 degrees above average
for this time of year. Tomorrow, just a tick "cooler" due to
increased cloud cover, in the upper-60s to mid-70s. Expect overnight
lows in the mid-40s to near 50.

96

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 511 AM EDT Wed Mar 12 2025

Key Messages:

  - Rain and a few thunderstorms may hang around the area Thursday
    night before the weakening system departs the area.

  - Not much change in the overall forecast for this weekend.
    Severe weather continues to look likely with the greatest
    chances being Saturday into Sunday. All severe modes remain
    possible - hail, tornadoes, and severe wind. An equivalent
    Enhanced Risk (Level 3 out of 5) is in effect.

Forecast:

Some lingering rain and thunderstorms may still be around on early
Thursday night when the long term forecast picks up as a quick
hitting upper level wave progresses across the area. Can`t rule out
something being strong, but with loss of daytime heating and not
much in the way of dynamics to support the system, chances of seeing
a strong to severe thunderstorm will have greatly diminished.
Anything ongoing should quickly begin to collapse.

Moving forward, the main focus remains the severe threat over the
weekend. Models remain consistent with the setup - a sharp wave will
dig into the west CONUS Thursday night and then eject into the Great
Plains on Friday. Lee cyclogenesis will occur driving surface low
and upper level system towards midwest/Great Lakes that becomes
increasingly vertically stacked and stalls. Cold front will be
driven into Arklatex region with copious moisture advection
occurring in the south from the Gulf. Models show the possibility
of some elevated rain/convection that could occur on Friday night
into Saturday morning (the Euro suite being a bit more aggressive
with this than the GEFS). This will need to be monitored,
especially given we are getting in range of higher resolution
guidance, as if any of this is able to tap into the boundary layer
the shear profiles in place will be a bit worrisome (hence the
Marginal Risk for Friday over NW GA). Following this, a secondary
wave pushes into larger trough over the CONUS and brings the
entire system to the east, with height falls overriding the moist
boundary layer in the southeast. Copious lift ensues alongside a
significant mass response. Low level jet of 60+ kts overspreads
north and central Georgia overnight Saturday into Sunday ahead of
a cold front as system progresses to the east. Severe weather
looks likely ahead of this, with all modes still possible
(tornadoes, wind, hail).

Questions remain on what if any convection could get going in the
warm sector ahead of the front given models continue to show a lack
of instability after sunset and relatively poor lapse rates before
that. However, shear profiles are impressive during the day into the
night, and if something can get going ahead of this could certainly
have the opportunity to have supercellular characteristics. This is
likely what would drive any hail threat. Going into the overnight,
the cold front pushing into the area will likely have an ongoing
linear system with embedded QLCS elements. While the thermodynamics
remain very marginal, ensembles still show decent probabilities of
seeing over 500 J/kg of CAPE which will be more than enough given
shear profiles. Hodographs continue to look quite elongated with
very impressive 0-1 km SRH of greater than 350-400 m2/s2 and 0-3 km
SRH approaching or exceeding 500 in some cases. Needless to say, if
something is capable of ingesting some streamwise vorticity, it will
have a hefty amount of it to work with to help with overcoming the
thermodynamic limitations. Tornadoes and damaging winds will likely
be in play as this line to broken line of storms marches across
north and central Georgia. SPC continues to maintain a risk area
equivalent to an Enhanced Risk (Level 3 of 5) for much of western
and northern Georgia, with equivalent Slight Risk (Level 2 of 5)
across the rest of the CWA.

QPF shouldn`t be left out of the discussion either, especially
given WPC maintains a Slight Risk of flash flooding over NW GA.
One potential "failure mode" for significant impacts in northern
Georgia may be a more steady stream of rain from the deep lift
into the system that results in even less favorable thermodynamics
at the surface that makes surface based convection difficult to
achieve. The trade-off will be a lot of rainfall in this scenario.
Experimental NBM 5.0 shows probabilities of rainfall greater than
3" over 48 hours to be about 60%. This likely wouldn`t create huge
impacts, but could lead to minor flooding. Probabilities drop off
quite a bit for over 5", going down to about 10%, which means that
5" is pretty representative of the probable worst case scenario
(90th percentile) over the two days (with the majority likely
falling on Saturday). This could lead to flash flooding and
impacts to local creeks and streams, which should be monitored.
Otherwise, forecast rainfall amounts are currently 1-3" across the
CWA.

On Sunday, this line of storms will likely be continuing to the east
as the entire system continues to shift. Shear from the upper level
won`t be quite as strong with eastward extent, but the system will
still have plenty to work with. Some reintensification of the line
may be possible during the afternoon with day time heating, but some
questions as to whether or not it will have already exiting east
central Georgia by that time. SPC equivalent Slight Risk area is in
line with this thinking on Sunday. Tornadoes and strong damaging
winds remain the primary threats as the system pushes to the east.

After this, not much to discuss. High pressure moves in behind the
front and things cool down a bit. Highs on Monday will be in the 60s
across much of north and central Georgia. Lows Monday night will dip
into the 30s, and that time period may need to be monitored for
frost.

Lusk

&&

.AVIATION...
(12Z TAFS)
Issued at 641 AM EDT Wed Mar 12 2025

Primarily VFR and SKC thru the TAF pd. SCT-BKN MVFR returns to
northern TAF sites by 13-14Z tomorrow, lingering into the
afternoon. Winds will be SW at 5-10kts.


//ATL Confidence...12Z Update...
High confidence all elements.

96

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          76  48  72  51 /   0   0  30  20
Atlanta         75  50  69  55 /   0   0  60  30
Blairsville     73  44  69  46 /   0   0  30  20
Cartersville    76  48  71  52 /   0   0  50  30
Columbus        77  50  72  56 /   0   0  80  20
Gainesville     74  49  70  51 /   0   0  30  30
Macon           78  47  73  53 /   0   0  50  30
Rome            77  48  71  50 /   0   0  60  30
Peachtree City  76  48  70  53 /   0   0  70  30
Vidalia         79  50  75  54 /   0   0  20  20

&&

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

$$

SHORT TERM...96
LONG TERM....Lusk
AVIATION...96