Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 161151
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
651 AM EST Tue Jan 16 2018


.UPDATE...

12z Aviation update below.

Baker

&&

.PREV DISCUSSION... /Issued 459 AM EST Tue Jan 16 2018/

.SHORT TERM /Today through Wednesday/...

Primary concern is onset and magnitude of light snow beginning this
afternoon. Near term hires models in good agreement with primary
model guidance that band of light snow should move into far NW GA
around noon to 1p today and slowly moving south toward the rest of
north and west GA during the afternoon. Since this system is more of
a post-frontal overrunning rather than an eastward-moving low
pressure system to our south, it`s going to be difficult to see much
precipitation, especially considering the strong push of cold/dry
air behind the front. That said, with sfc temps eventually going
well below freezing, it won`t take much precip to cause impacts on
roads. Based on latest QPF and temperature guidance, our snow
amounts went up just a touch, but still mostly remain below 1.0
inch. Another change we saw in recent guidance was the development
of a secondary band of light snow over southern AL into westcentral
GA during the evening hours. This band could produce up to 1 inch
just by itself as it pushes from the LaGrange and surrounding areas
into the south ATL metro.

By Wed morning, temps should have bottomed out while wind speeds
peak. At this time, WCI values are in the single digits to around
zero over much of north and west GA and well below zero in the
mountains. Wind chill warning criteria may be met in a few spots in
the higher elevations but have kept this area as a separate segment
in the advisory for now.

Black ice may be an isolated problem Wednesday where snow amounts
are an inch or higher, but with such light amounts of liquid-
equivalent precip, strong winds, abundant sunshine and dry air, do
not believe there will be much to refreeze.

SNELSON

&&

.LONG TERM /Wednesday Night through Monday/...

A deep trough will be moving off the east coast at the start of the
period with a transition to a northwest to west flow aloft. A very
dry air mass will spread over the forecast area and persist until
late in the weekend. GFS/ECMWF in general agreement of an increase
in moisture on Sunday as high pressure moves off the east coast and
low level winds become southerly. A strong short wave moving through
the upper MS Valley late Sunday into Monday will push a cold front
through north and central GA on Monday. Pops will increase across
the area Sunday into Monday. A strip of low CAPE approaches the west
central counties on Monday and isolated thunder is not out of the
question...but for now have kept the mention of thunder out.

41

&&

.AVIATION...
12Z Update...
Initial VFR conditions then approaching strong cold front late
afternoon into evening with increasing chance of -SN (especially
for northern TAF sites). Cigs should decrease to MVFR after about
00z for near KATL along with increasing -SHSN chance - have made
predominant given increased chance/confidence in amounts mainly
0.5-1 inch near KATL. Less confident for other sites to east and
south so left prob30 groups accordingly. Should start
improving/scattering after 06z. Expecting increased NW winds of
near 8-12 kts gusting 18 kts with higher mags for tomorrow.

//ATL Confidence...12Z Update...
Medium on timing of -SHSN this evening.
High on all else.

Baker

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          50  23  35  20 /  10  50  20   0
Atlanta         48  15  29  18 /  30  50  10   0
Blairsville     41  12  24  13 /  70  70  10   0
Cartersville    44  12  28  16 /  70  80   5   0
Columbus        55  21  34  20 /  10  60  20   0
Gainesville     46  19  30  19 /  30  40  10   0
Macon           55  26  35  21 /   5  40  30   0
Rome            41  11  29  16 /  90  80   5   0
Peachtree City  51  17  31  18 /  30  60  10   0
Vidalia         57  33  39  24 /   5  20  30   0

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 PM this afternoon to 7 AM EST
Wednesday for the following zones: Banks...Barrow...Butts...
Carroll...Chattahoochee...Cherokee...Clayton...Cobb...Coweta...
Crawford...Dawson...DeKalb...Douglas...Fayette...Forsyth...
Gwinnett...Hall...Haralson...Harris...Heard...Henry...Jackson...
Lamar...Lumpkin...Marion...Meriwether...Monroe...Muscogee...
Newton...North Fulton...Paulding...Pike...Rockdale...Schley...
South Fulton...Spalding...Stewart...Talbot...Taylor...Troup...
Upson...Walton...Webster...White.

Wind Chill Advisory from 9 PM this evening to 1 PM EST Wednesday
for the following zones: Bartow...Carroll...Catoosa...
Chattooga...Cherokee...Clayton...Cobb...Coweta...Dade...DeKalb...
Douglas...Fayette...Floyd...Forsyth...Gordon...Gwinnett...Hall...
Haralson...Harris...Heard...Henry...Meriwether...Murray...North
Fulton...Paulding...Pike...Polk...Rockdale...South Fulton...
Spalding...Troup...Walker...Whitfield.

Winter Weather Advisory from noon today to 7 AM EST Wednesday
for the following zones: Bartow...Catoosa...Chattooga...Dade...
Fannin...Floyd...Gilmer...Gordon...Murray...Pickens...Polk...
Towns...Union...Walker...Whitfield.

Wind Chill Advisory from 9 PM this evening to 8 AM EST Thursday
for the following zones: Dawson...Fannin...Gilmer...Lumpkin...
Pickens...Towns...Union...White.

&&

$$

SHORT TERM...Baker
LONG TERM....41
AVIATION...Baker


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