Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 092259
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
559 PM EST Fri Dec 9 2016



.UPDATE...
Updated for the 00Z Aviation Discussion.

&&

.PREV DISCUSSION... /Issued 245 PM EST Fri Dec 9 2016/

SHORT TERM /Tonight through Saturday Night/...
Surface high pressure over the Plains will build eastward to over
the Mid Atlantic States by early Sunday morning. Although the high
will remain just north of the forecast area as it moves across
portions of TN tomorrow, it will be close enough to bring light
and variable winds, with wind speeds of 5miles an hour or less
across the area after 00Z. This will set up good radiational
cooling across the forecast area under clear skies. Saturday
morning`s low temperatures are expected to be at least a couple of
degrees cooler than this morning. I have undercut model guidance
by a degree or so all sites. Atmosphere remains dry and few if any
clouds are expected through the short term.

Atwell

LONG TERM /Sunday through Friday/...
Did not make many changes to the long-term...as previous discussion
still in line with latest guidance. Biggest change was to add
thunder early next week as pre-frontal dewpoints/Gulf moisture
return may be enough to attain several hundred J/KG MUCAPE.

Sfc wedge will be in place across the Southeast at the beginning of
the period. This feature should keep temps on the cool side...along
with return flow setting up a WAA regime in the lower levels to aid
in increasing cloud cover. Could see a few showers develop but
most...if not all...locations should be dry.

Late Sunday into Monday the next front will approach the area. This
will lead to an increasing chance of rain and perhaps some thunder
across the area. With no legit upper level support and the lower
level dynamics displaced well north...this boundary will likely
stall across the area. This will keep scattered showers and perhaps
some thunderstorms across the area until late Wednesday.

By late Wednesday...a strong mid level vortex will set up around
Hudson Bay...allowing a strong arctic front to intrude upon the
northern US border. Normally this setup is good for bringing cold
weather into the eastern US. However...after consulting ensemble data
/which shows rather progressive pattern as well as keeping
anomalously cold temps north of us/ as well as agreeing with the
previous forecaster reasoning...think the airmass will modify
enroute to the SE. That being said...still looking at below normal
temps by the end of the period. See previous discussion below.

Kovacik

PREV DISCUSSION...

LONG TERM /Saturday Night through Thursday/...
Models are struggling a bit in the long term when it comes to a
couple of fronts approaching the area. To start the long term,
models are in good agreement with High pressure to the north
yielding the typical CAD profile across north/central Georgia
Sunday. This will allow temperature to stay below climo for those
within the wedge, around 50 degrees to around 60 across the south.
The sfc high will eventually push offshore ahead of the next
system. A cold front associated with a potent low ejecting out of
the central CONUS will move toward Georgia by Monday. This will
mean an increase chance of precipitation through the day as the
front approaches. The models start to diverge a bit on the exact
placement of the front. The boundary will then act as a focus for
a series of sfc lows to ride northward. This means warmer and more
wet conditions through mid-week. The exact placement of the front
will heavily influence temperatures and precipitation through
this period. Only expecting a half an inch of rain or so from
Sunday night through Wednesday.

A sfc low will develop off the Carolina coast and move out to
sea Wednesday, all ahead of the next trough and associated cold
front progged to cross Thursday. Models tend to go back and forth
on the amplitude of such troughs this time of year due to the
projected snow cover to the north and forecasted temps across the
Great Lakes. More often than not, we see models moderate a bit when
it comes to these troughs because of the aforementioned trends.
However, I think confidence is building that another shot of cooler
air may move through the latter portion of the work-week. Cold high
pressure across the Dakotas will start to build east, with below
normal temps possible by the end of the period.

26

&&

.AVIATION...
00Z Update...
VFR conditions through the forecast. A few cirrus will move across
the forecast area through 00Z SUN. Winds will become calm/near
calm tonight...then northeast 5 kts or less Saturday.

//ATL Confidence...00Z Update...
High on all elements.

17

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          24  47  28  48 /   0   0   0  10
Atlanta         26  47  31  48 /   0   0   0  10
Blairsville     20  43  24  46 /   0   0   0  10
Cartersville    22  46  29  49 /   0   0   0  10
Columbus        27  51  32  56 /   0   0   0  10
Gainesville     24  46  29  45 /   0   0   0  10
Macon           25  51  30  54 /   0   0   0  10
Rome            21  46  25  51 /   0   0   0   5
Peachtree City  23  48  27  50 /   0   0   0  10
Vidalia         29  52  35  59 /   0   0   0  10

&&

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

$$

SHORT TERM...17
LONG TERM....01
AVIATION...17



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