Area Forecast Discussion
Issued by NWS Atlanta, GA

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224
FXUS62 KFFC 181917 AAA
AFDFFC

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
217 PM EST Wed Jan 18 2017

.UPDATE...
Near term forecast in good shape. Showers have dissipated and
clouds continue to clear over most of North GA and temps quite
warm. KAHN may tie or break their daily record max temp of 76
today. Does not appear any other daily records will be tied or
broken.

SNELSON

&&

.PREV DISCUSSION... /Issued 646 AM EST Wed Jan 18 2017/

SHORT TERM /Today through Thursday/...
Water vapor loop early this morning shows a large trough in the
mid/upper levels across the SW US and S. Plains with numerous vort
maxes rotating about. A compact northern stream shortwave trough
was also noted across IN/OH...with more zonal flow across the CWA
and a building...diabatically-induced...shortwave ridge just to
the west. At the sfc...a weak cold front was draped across the
Appalachians SW into NW Ga and AL/MS.

For today...dynamics from northern stream vort max should help
sustain some showers along the cold front this morning across north
Georgia. Temps have been slow to fall with moist airmass in place
along with abundant cloud cover. As the front pushes more into the
state...low temps across northern tier should fall into the 50s.
Have opted to keep shower chances primarily along the cold front
today and it progresses south. However...activity becomes much
more isolated as the day wears on due to loss of upper level
support from parent system along with shortwave ridge arguing for
subsidence as it builds into the area from the west. Lack of
appreciable MUCAPE /warm mid levels/ will preclude mention of
thunder today. Despite cloud cover...kept temps well-above normal
once again as airmass remains stagnant. Position of the front
today will have an impact on north Ga high temps...thinking front
will stall between ATL and MCN...with far north Georgia seeing the
drier/slightly cooler airmass by day`s end as weak sfc high
settles in. Looking at highs lower 60s north to upper 70s central.

Tonight: Weak post frontal sfc high pressure should creep a little
further south into the CWA...possibly down towards ATL as front
remains stalled across central Ga. Low temps will range from 40s
north to upper 50s central. Weak ridging aloft and lack of forcing
should keep most everyone dry overnight.

Thursday: Near daybreak...sfc high will attempt to ridge down the
mountains and create a weak wedge. This should push some of the
drier air into E Central Ga...just not sure how far west the wedge
will make it. In the meantime...moisture transport will increase
across the Gulf states as sfc low develops in Arklatex region in
response to shortwave across S Plains. This will allow stalled
boundary to lift north as a warm front /keeping high temps warm
again/. This next system will approach the CWA at the end of the
period...bringing a nice batch of rain and some thunder for the
beginning of the extended.

Kovacik

LONG TERM /Thursday Night through Tuesday/...
No big change to the overall pattern in the long term. A series of
waves will affect north and central GA through the period with the
best chances for rain Thursday night and again Sunday night. The
upper closed low moving into the mid MS valley Thursday night
should bring increasing chances for showers and thunderstorms to
the forecast area. A few strong storms are possible Thursday night
however instability may be limited by existing daytime cloud
cover. This system moves rapidly to the east and there may be a
brief break for Friday night for parts of the area. Southwest flow
aloft will continue to bring impulses through the southeast states
into the weekend. A strong closed low moving across the lower MS
valley and into the southeast will bring another chance for
possibly a few severe storms Sunday night into early Monday. GFS
ans ECMWF differ on speed and track of this system...however
expect increasing showers and thunderstorms for that time frame.
Ridging across the southeast for Tuesday should bring drier air.

Temperatures will continue warm through the period...however
overnight lows should dip into the 40s by the first of next week.

41

&&

.AVIATION...
18Z Update...
Only concern with this forecast cycle is timing and likelihood of
MVFR cigs Thurs morning. Appears 1500ft cigs may develop as early
as 12Z at all forecast points, except KAHN, before clearing up by
19Z. NW sfc winds will become NE 3-5kts around 10Z then SE 5-7kts
around 15Z. Any SHRA would move in well after 00Z Fri.


//ATL Confidence...18Z Update...
Medium confidence for timing and likelihood of MVFR cigs.
High confidence all other elements.

SNELSON

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          73  47  65  53 /  30  10  20  80
Atlanta         70  53  68  57 /  30  10  40  80
Blairsville     62  44  60  49 /  30  10  60  90
Cartersville    64  48  66  55 /  30  10  50  90
Columbus        74  56  72  59 /  20  10  40  80
Gainesville     66  49  63  53 /  30  10  30  80
Macon           74  53  72  58 /  20  10  20  80
Rome            63  47  66  55 /  30  20  60  90
Peachtree City  71  48  68  56 /  30  10  40  90
Vidalia         76  56  73  59 /  10  10  10  60

&&

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

$$

SHORT TERM...SNELSON
LONG TERM....01
AVIATION...SNELSON



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