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Area Forecast Discussion
Issued by NWS Atlanta, GA
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FXUS62 KFFC 181855
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
255 PM EDT Thu Apr 18 2024



...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This afternoon through Friday)
Issued at 238 PM EDT Thu Apr 18 2024

Low confidence pop forecast for overnight and into tomorrow.

Challenging forecast for tonight into tomorrow. The models,
including the hi-res, continue to struggle with the convection
near the ARKLAMISS. The hi-res models do weaken any convection as
it nears the AL/GA state line late this afternoon into the evening
hours. Do think some weakening will occur due to loss of heating,
but coverage of storms may be a bit more than the models are
progging. There will be enough surface instability around through
the early evening for isolated/scattered thunder and the lapse
rates remain pretty steep. Luckily shear remains pretty low.
Strong storms are possible with an isolated severe storm not out
of the question, mainly near the central AL/GA border. Strong
storms will be capable of producing gusty winds and hail.

A break in storms is likely well into the overnight hours. The
models are progging a second round of storms (MCS) potentially
moving in from the NW towards 12Z. There has been some run to run
consistency within the HRRR, but the hi-res models remain all over
the place with the evolution of this system. With such
uncertainty with this system, will refrain from using likely pops
and stick to scattered at this time. However, if models come into
better agreement, pops will have to be adjusted upwards.

A third round of storms is possible again tomorrow as a front
sags south across northern portions of the state. Convective
initiation will be highly dependent upon any morning convection
that moves through. If there is good coverage of storms with the
early morning MCS, then initiation may be later in the day. If the
early morning MCS falls apart near the border, then convective
initiation/coverage should be greater tomorrow afternoon.

With all of this said, the models struggle with these types of
systems...especially the timing. However, if/when convection
fires, it will definitely have the potential to be strong or
severe, especially tomorrow afternoon. CAPE values should be
around 1500 J/kg with steep lapse rates. Shear remains low, but
frontal forcing will be another player. Damaging wind gusts and
large hail would be the primary severe thunderstorm hazards.

NListemaa


&&

.LONG TERM...
(Saturday morning through next Wednesday)
Issued at 238 PM EDT Thu Apr 18 2024

The long-term period picks up on Saturday with 25% to 40% PoPs in
the afternoon and evening, generally along and south of I-20. The
SREF is progging SBCAPE of 800-1200 J/kg across said area, which
indicates the potential for isolated to scattered showers and
thunderstorms. The greatest surface-to-500-mb bulk shear will be
much farther north, so the setup will not be conducive for
organized convection. That said, a few strong to severe storms
posing a hail threat and downburst threat cannot be ruled out. A
southern-stream shortwave trough passage on Sunday will increase
the surface-to-500-mb bulk shear to 40-50 kts, and while the SREF
is progging less instability on Sunday, thinking is that the
shortwave will provide enough lift to warrant a 60% to 80% chance
for showers with a 15% to 25% chance for thunderstorms. Again,
widespread severe weather is not expected, but a strong to severe
storm or two are possible. Continuing to message a QPF of ~0.50"
to 0.80" with this weekend rainfall.

On Monday, the shortwave and larger-scale, synoptic trough axis
will shift east of the forecast area, pushing a cold front
through. Much drier air will overspread the forecast area as high
pressure settles across a portion of the eastern CONUS. The
airmass associated with the high pressure will be noticeably
cooler starting on Sunday and continuing into early next week with
lows in the 40s and 50s, and highs in the 60s and 70s.

Martin


&&

.AVIATION...
(18Z TAFS)
Issued at 119 PM EDT Thu Apr 18 2024

Challenging forecast within the fast moving flow aloft. Several
rounds of shra possible overnight through tomorrow as upper level
disturbances move through the area. Timing on all systems is
usually not handled well by the models. VFR cigs likely with some
patchy sct MVFR overnight. Winds will remain on the west side.

//ATL Confidence...18Z Update...

Med confidence on evening convection timing. Low confidence on
early tomorrow and tomorrow afternoon. High confidence remaining
elements.

NListemaa


&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          65  86  63  83 /  20  30  30  30
Atlanta         66  85  62  79 /  30  30  30  30
Blairsville     60  77  55  73 /  40  40  30  20
Cartersville    63  83  58  76 /  30  30  30  20
Columbus        67  88  67  86 /  30  20  20  40
Gainesville     65  83  62  80 /  30  30  30  20
Macon           67  88  66  86 /  20  20  20  40
Rome            65  82  58  75 /  40  30  30  20
Peachtree City  65  86  62  81 /  30  30  30  30
Vidalia         67  90  69  89 /  10  20  20  40

&&

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

$$

SHORT TERM...NListemaa
LONG TERM....Martin
AVIATION...NListemaa
National Weather Service Regional Headquarters
