413
FXUS62 KFFC 171954
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
254 PM EST Fri Nov 17 2017


.SHORT TERM /Tonight through Saturday Night/...

Surface high pressure continues to build eastward into the Atlantic
through morning. The upper level ridge will flatten overnight as
well, allowing a short wave to trek across the Gulf Coast states
through the day tomorrow.  As the surface high gives way to an
approaching cold front tomorrow evening, return flow will set up
tomorrow, bringing increasing moisture ahead of the front. Mostly
clear skies this afternoon and evening will give way to mid and high
clouds overnight which should keep overnight lows warmer than this
morning, and closer to climatological normals for this time of year.
Clouds will increase tomorrow, with the cloud deck lowering by late
morning. Rain chances will increase tomorrow afternoon ahead of the
front, and while there is enough shear, instability is minimal and
expect any isolated thunderstorms to be elevated and generally in
the 00-06 hours on Sunday. The gradient ahead of the front is quite
sharp, and expect gusty southwest winds across the area by late
morning tomorrow.  Higher elevations of the north Georgia mountains
will have wind gusts that reach wind advisory criteria beginning
late Saturday morning.  See ATLNPWFFC for more information.  These
gusty southwest winds will bring warmer air across the area, and
even with the additional cloud cover, expect afternoon high
temperatures to moderate to near this afternoon or slightly warmer.
The front pushes through the area Saturday night with rain tapering
off from northwest to southeast after 06z.

Atwell

&&

.LONG TERM /Sunday through Friday/...

No large wholesale changes made to fcst with latest guidance
blend. Still some uncertainty in the latter half of the week due
to slight discrepancies on extent of Gulf moisture and trough
influence to the west/SW, so have played mainly slight chance
pops to central GA and parts of northeast. Previous discussion
follows...

Baker

PREV DISCUSSION... /Issued 455 AM EST Fri Nov 17 2017/

LONG TERM /Saturday Night through Thursday/...

The beginning of the long term period starts as a cold front makes
its way into far NW GA driven by a deep surface low pressure
system located around Lake Ontario. A line of showers will most
likely accompany this frontal system but what little rain that is
expected will mostly be contained to the NW of the I-85 corridor.
MUCAPE is low along the FROPA but not non-existent, and low-level
convergence and higher shear values leads me to believe very scattered
thunderstorms may be possible. However, the vertical thermodynamic
profile suggests updrafts in any potential thunderstorms should
be relatively shallow and non-severe.

A sharp pressure gradient will mean winds will be rather strong
ahead and along the frontal passage with wind gusts expected to
reach 20-30 mph on Saturday afternoon and evening. Localized
higher amounts will be possible in the higher elevations of the
north Georgia mountains where wind gusts above 40 mph may be
possible. Conditions will need to be monitored to determine
whether a wind advisory will be needed.

Cooler and dryer air will make its way into the area behind the
front on Sunday as an area of high pressure meanders across the
area through Tuesday evening.

Model solutions begin to diverge at the end of the long term
period, as a Rossby wave train begins to affect the upper level
jet stream pattern. The Euro elected to form a cut-off low
pressure system over the Gulf that would bring higher cloud cover
and rain chances to the area, however, I`m currently more inclined
to lean more towards the slightly more consistent GFS which
instead forms a deep positively tilted trough over the Gulf and
keeps the more significant moisture further south. Therefore, have
gone with no more than chance Pops until models come to better
agreement.

Thiem

&&

.AVIATION...
18Z Update...
VFR conditions will persist until late in the forecast period.
MVFR with SCT-BKN030-040 will move into ATL area TAF sites after
13Z tomorrow morning. Winds out of the EAST today will veer out of
the SW after 12Z tomorrow and increase with speeds 5-13g20-25kts
after 14-15Z.

//ATL Confidence...18Z Update...
Medium to high confidence all elements.

Atwell

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          42  68  43  55 /   0  20  60   5
Atlanta         47  69  42  52 /   0  20  60   0
Blairsville     40  62  36  47 /   0  50  80   0
Cartersville    46  68  41  51 /   0  40  70   0
Columbus        47  73  46  57 /   0  10  60   5
Gainesville     44  65  42  52 /   0  30  60   0
Macon           43  73  46  58 /   0   5  40   5
Rome            46  69  41  51 /   0  50  80   0
Peachtree City  43  70  42  54 /   0  20  60   0
Vidalia         47  74  52  62 /   0   0  40  10

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM Saturday to 3 AM EST Sunday for the
following zones: Bartow...Catoosa...Chattooga...Cherokee...
Dade...Dawson...Fannin...Floyd...Gilmer...Gordon...Lumpkin...
Murray...Pickens...Towns...Union...Walker...White...Whitfield.

&&

$$

SHORT TERM...Atwell
LONG TERM....Thiem/Baker
AVIATION...Atwell

NWS FFC Office Area Forecast Discussion