Area Forecast Discussion
Issued by NWS Atlanta, GA

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702
FXUS62 KFFC 171951
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
251 PM EST Tue Jan 17 2017


.SHORT TERM /Tonight through Wednesday Night/...

Ridge of high pressure situated over northeast GA will erode into
Wednesday as low pressure approaches the state from the west. As the
cold front approaches, the band of enhanced moisture stretching
across the Tennessee Valley will sink into north Georgia. Short term
models in agreement with nosing in higher CAPE values into northwest
and portions of western GA late tonight and into the overnight
period. CAPE does continue to be meek at best, and general thunder
still seem appropriate. Have continued mention of slight chance
thunder in the grids through midnight. Best forcings continue to be
well north of the system, and most of the hi-res models are
indicating that as the front pushes into the state overnight,
precipitation coverage will diminish everywhere except right along
the boundary. This trend will continue through the day Wednesday
with most of the short term models indicating little in the way of
precipitation even with the front stalling just south of the metro
area. Latest forecast package really confines precip chances
Wednesday afternoon to the western half of the state, and still only
slight chance showers. By early Thursday, the front begins to shift
northward as a warm front, spreading higher pops across the area by
sunrise Thursday.

Temperatures remain above normal through the period, and have
generally gone with a guidance blend through the short term.

31

&&

.LONG TERM /Thursday through Tuesday/...

Latest refresh of guidance blend does not deviate much from
previous forecast so just minor adjustments to this package. Have
a slightly quicker progression to the first wave/system and
trimmed pops on the exit for Friday night...though still looking
at the late Saturday/Sunday system to be the more potent system.
Instability and shear parameters still support an increasing
concern for strong/severe convection starting Saturday night.
Please keep monitoring future updates while this is still far out
in the forecast and timing/intensity can easily change. Previous
discussion follows...

Baker

PREV DISCUSSION... /Issued 348 AM EST Tue Jan 17 2017/

LONG TERM /Wednesday Night through Monday/...
Unsettled weather still on tap for the long term portion of the
forecast. Fast flow will dominate aloft, so expect several systems
to impact the area through the end of the week into early next week.

An old frontal boundary will begin pushing back northward as a warm
front Wednesday night into Thursday as a low pressure system moves
into the Lower Mississippi River Valley. Pops will be on the
increase during the day Thursday as the boundary pushes north and
the low pressure system/front approaches from the west. Models are
progging some minimal instability with this system, so thunder still
looks appropriate. The front briefly settles across southern
GA/northern FL before beginning to push back north late on Saturday
ahead of the next low pressure/frontal system.

Copious moisture is expected ahead of the late weekend/early next
week system. Pops remain high. The parent low with this system
rapidly moves east from the center of the country to the TN valley
by early Sunday, dragging a frontal boundary through the CWFA later
Sunday/early Monday. This is a potent system...strong mid level
energy aloft will give support for widespread showers and
thunderstorms. Currently, good shear and very steep lapse rates are
progged, so there is good potential for severe thunderstorms. Now,
this is still Day 5/Day 6, so the forecast could change, stay tuned!

NListemaa

AVIATION...
18Z Update...
Increasing clouds expected as rain moves into NW GA this
afternoon. VFR conditions through the evening will degrade to IFR
overnight. Patchy LIFR is possible, particularly across central
GA. Any shower and thunderstorm activity should stay north of TAF
sites through tonight, with isolated shower activity spreading
into central GA early Wednesday. Chances low enough not to include
in the TAF at this time. Winds have shifted to the west and are
expected to shift to the NW through the TAF period. Speeds will be
8-12kt with gusts to 20-22kt this afternoon, then diminish to 8kt
or less overnight, and remain 5-10kt Wednesday.

//ATL Confidence...18Z Update...
Medium on shower chances at KATL.
Medium on ceilings and visibilities 02-16z.
High confidence on all other elements.

31

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          58  69  50  64 /  20  20  20  20
Atlanta         58  66  53  66 /  20  20  20  40
Blairsville     52  60  45  60 /  60  30  40  50
Cartersville    57  64  50  65 /  40  20  40  50
Columbus        59  72  56  71 /  20  20  20  40
Gainesville     57  65  50  62 /  40  20  20  30
Macon           58  73  54  71 /  10  20  10  30
Rome            56  63  50  66 /  50  20  40  60
Peachtree City  58  68  52  67 /  20  20  20  40
Vidalia         59  75  57  73 /  10  10  10  20

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...31
LONG TERM....NListemaa/Baker
AVIATION...31



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