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000
FXUS62 KFFC 181135
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
735 AM EDT Thu Apr 18 2024



...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Friday)
Issued at 331 AM EDT Thu Apr 18 2024

The line of showers and thunderstorms from yesterday evening has
dissipated as the boundary moved into central Georgia. In portions
of far northwest Georgia, observations have begun to indicate
visibilities of 1/4 SM or less. With winds in this area forecast to
remain light (3 mph or less) and relative humidity values forecast
to range from 95-100% as cooler air overruns wet soil, dense fog is
expected to persist through the early morning hours. As a result, a
Dense Fog Advisory has been issued for an area along and west of a
line from Paulding to Murray county, and will remain in effect until
10 AM EDT. A weak 500 mb ridge will quickly move across the east-
central CONUS today. The subsidence under this ridge will inhibit
rain chances through much of the daytime on Thursday and diminish
cloud coverage from the northeast this morning into the afternoon.
In spite of this, little change is anticipated in the airmass at the
surface. With plenty of sunshine, high temperatures are forecast to
rise to 9-14 degrees above climatological normals, into the mid 80s
in north Georgia and upper 80s in central Georgia.

As the ridge quickly moves away to the east this afternoon, zonal
upper level flow will set up over the region. A shortwave traversing
the upper level flow will move through the Ozarks region tonight. A
cold front associated with this disturbance will advance towards
TN/KY. Hi-res guidance continues to indicate a weakening MCS moving
into far north Georgia late tonight into early Friday morning. This
MCS is most likely to move from west to east across the far northern
tier, with a couple of storms within being capable of producing
gusty winds. That said, the motion and evolution of this system will
depend on the behavior of the outflow boundary from storms upstream,
which makes nailing down the specifics of these MCS systems a
challenge.

Low temperatures are anticipated to start Friday morning in the mid
60s across the majority of the area. Increased cloud coverage will
inhibit diurnal heating in far north Georgia, where high
temperatures will be in the upper 70s to low 80s. Elsewhere across
the forecast area, highs will reach into the mid to upper 80s once
again. On Friday afternoon, the aforementioned cold front will
advance into north Georgia and towards central Georgia, providing a
source of lift within a favorable environment for convective
activity. At this time, likely PoPs are forecast across the far
northern tier with chance PoPs to the south on Friday afternoon.
Considering the warm temperatures and dewpoints in the low to mid
60s, SBCAPE values will climb to between 1500-2000 J/kg in the peak
heating hours. Combined with deep layer bulk shear values between 30-
40 kts and steepening low level lapse rates, there is the potential
that isolated storms could become strong to severe, capable of
producing large hail and damaging wind gusts.

King

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 331 AM EDT Thu Apr 18 2024

4/17 LONG TERM

At a glance:

    - Isolated to scattered thunderstorms this weekend

    - Cooler, drier start to next week behind cold front

Moving into the weekend and the extended range, flow remains quasi-
zonal at the mid-levels. The eastward movement of an expansive
closed-low rotating over central Canada is progged to send a cold
front sweeping across ECONUS, and lingering frontal precipitation is
likely to be ongoing across central Georgia on Saturday. Isolated to
scattered thunderstorms are possible (especially along and south of
I-20) where ensemble guidance gives a 30-50% chance of at least 500
J/kg of SBCAPE. In the absence of dynamic forcing aloft, expecting
any storms that form to be fairly run of the mill, producing gusty
winds and locally heavy rainfall at times. On Sunday, a weak
shortwave impulse will send a stronger slug of moisture across
the Deep South, reinvigorating rain chances as it overlaps with
our residual frontal forcing. As a result, expect our highest and
most widespread chances for showers and thunderstorms to come as
we round off the weekend. Even so, rainfall totals across both
days are likely to be half of an inch or less.

Any lingering moisture -- and what remains of our front -- will be
nudged offshore by a (relatively) stronger shortwave that will
dig to the south and east across the Midwest and Ohio River Valley
on its way to the Eastern Seaboard. Precipitation chances will be
effaced as drier air moves in in the wake of the aforementioned
feature, making for a cooler and drier start to next week.

Highs Saturday and Sunday will be governed by how far into the
forecast area the front mixes. For now, Saturday`s highs will be
roughly delineated along I-85: in the 70s to the north, in the 80s
to the south (even near 90 in the vicinity of Macon). Sunday will be
very cool -- as much as 12 to 16 degrees below average -- especially
when compared to the past few days in the 80s: in the upper-50s to
60s north of Columbus and Macon, and in the 70s to the south.
Following the frontal exit, expect our dry airmass to moderate and
warm, and highs will eventually reach back into the upper-70s to 80s
areawide. Lows will fall into the upper-40s to 50s each day.

96

&&

.AVIATION...
(12Z TAFS)
Issued at 722 AM EDT Thu Apr 18 2024

Dense fog remains across portions of northwest Georgia, with patchy
fog and LIFR ceilings intermittently reaching FTY/RYY for the last
few hours. Lower ceilings and visibilities are not expected to reach
ATL at this time. The fog should diminish by 14Z, giving way to VFR
conditions across the area. Winds will be fairly light through the
period, from 3-6 kts. Winds will be mainly NW this morning, shifting
to SW by 17Z and through the afternoon. A weakening complex of
SHRA/TSRA could move across north Georgia on Friday morning,
although much uncertainty remains with the timing and movement of
this system. At this time, a PROB30 for -SHRA has been introduced
from 10-14Z at ATL.


//ATL Confidence...12Z Update...

Medium confidence on all elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          63  85  62  84 /  30  30  10  30
Atlanta         65  84  63  81 /  30  40  10  30
Blairsville     58  77  56  74 /  60  70  10  20
Cartersville    63  82  58  78 /  40  50   0  30
Columbus        66  88  65  86 /  20  20  10  40
Gainesville     64  82  61  81 /  40  40   0  30
Macon           65  88  65  87 /  20  20  10  40
Rome            63  83  59  76 /  60  60  10  30
Peachtree City  65  86  62  82 /  20  40  10  40
Vidalia         66  90  67  90 /  10  20  10  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM EDT this morning for GAZ001>005-
011-012-019-020-030-031-041.

&&

$$

SHORT TERM...King
LONG TERM....96
AVIATION...King