Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 110819
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
319 AM EST Sun Dec 11 2016



.SHORT TERM /Today through Monday/...

Models agree on a weak surface wedge of high pressure nosing down
from the east being overrun by a developing moist southerly mid
level flow today. This is already setting up... with latest
satellite loop and regional observations showing low level stratus
clouds beginning to spread northward from southeast GA. These clouds
should spread over much of the forecast area through the morning...
resulting in a cool/cloudy day. Moderate isentropic lift and
increasing gulf moisture will help to gradually saturate the lower
levels by this evening and overnight... resulting in areas of light
rain and drizzle...with the greater rain chances across mainly north
GA tonight. Models agree on a cold front approaching the area on
Monday and this should help erode the surface wedge as low level
winds veer more southerly by late Monday morning... then southwest
by Monday afternoon. This will allow the area to warm sector and
should support scattered to numerous shower development by Monday
afternoon if not sooner. Still not seeing sufficient instability or
forcing to support thunderstorms... but will continue to monitor
this potential closely. Rainfall amounts will be light through
Monday with areas generally north of the I-85 Corridor maybe seeing
between 0.25 to 0.50 inch of rainfall while areas further south
possibly a trace to less than 0.25 inch.

As for temps... the cool easterly flow and increasing clouds will
hold highs today in the 40s... except for areas to the far west and
south where highs could creep into the 50s. Ample clouds will hold
lows tonight mostly in the 40s... with maybe some 30s far east deep
in the wedge. Area temps rebound nicely into the 60s and 70s on
Monday as the wedge front retreats north and the area warm sectors
by the afternoon. Otherwise... a blend of guidances for pops and
temps looked reasonable... so did not stray far.

39


.LONG TERM /Monday Night through Saturday/...

A front will be crossing northern Georgia to start off the long
term. Given much of the dynamics will be well north of the area,
would not be surprised to see precipitation dwindle a bit
overnight Monday as the front stalls across central Georgia.
Given a more amplified jet stream to the north is expected, feel
we will have a bit of forcing to allow a series of sfc lows to
develop along this stalled front, especially Tuesday through
Wednesday. This will mean the main focus for any precipitation
will be along this boundary. Looking at the various model suites,
it becomes clear that the GFS is the drier of the solutions for the
first half of the work week. The NAM has suggested there might be
very marginal instability Tuesday with the more potent low develop
along this boundary. Not enough to warrant thunder however. The
exact placement of the front Tuesday through Wednesday will
heavily influence the precipitation coverage/intensity as well as
temperatures. So from Sunday night through early Thursday,
thinking we will have around a half an inch of rain area wide.
Some localized higher/lower amounts can be expected with this type
of pattern. The temperatures will be above normal through
Wednesday.

As an upper level trough approaches Wednesday night/early
Thursday, expect the boundary/sfc lows to push southeast of the
region allowing for cool high pressure to build in from the
north. This will usher in the strongest cold air advection Wednesday
night into Thursday. The sfc high will settle into New England
Friday with the typical CAD profile developing across
north/central Georgia. This will keep temps below average Thursday
into early Saturday. As the high moves offshore and a deep
trough/associated sfc low crosses the upper mid-west, anticipate
southerly flow to develop by Saturday afternoon. The front
associated with the aforementioned low will approach Saturday
night with an increase chance of precipitation during this time.
The front will attempt to cross late Sunday/Sunday night as high
pressure tries to build in yet again. Of course looking this far
out yields a bit of uncertainty, but the upper/mid level pattern
seems quite progressive to support yet another frontal passage.

26


&&


AVIATION...
06Z Update...
VFR conditions are expected to continue overnight. Then model
guidances agree on MVFR cigs spreading up from the south and over
the Atlanta TAF sites by 14z-15Z later this morning. The MVFR cigs
will lower to IFR levels by 00Z-03z Mon and may even lower to LIFR
levels by 06-09z Mon when -RADZ is expected to become prevailing.
Easterly winds around 6-8kts is expected to prevail through
tonight... but could begin to veer slightly more ESE by 12z Mon.
Best rain chances will begin north of ATL/AHN this afternoon and
into early this evening... but -RADZ along with MVFR Vsby`s should
gradually spread into Atlanta and most TAF sites by 04-06z Mon.

//ATL Confidence...06Z Update...
Medium on timing of MVFR and IFR cigs/vsby.
High on remaining elements.

39

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          44  39  60  50 /  20  30  60  60
Atlanta         46  41  61  53 /  10  40  70  60
Blairsville     43  37  54  43 /  20  70  80  50
Cartersville    46  41  58  50 /  10  70  80  50
Columbus        54  48  70  56 /  10  30  60  60
Gainesville     43  37  56  48 /  20  50  70  60
Macon           52  45  69  57 /  10  30  40  50
Rome            48  42  58  48 /  10  70  80  40
Peachtree City  47  42  62  53 /  10  40  60  60
Vidalia         57  50  73  58 /  10  20  30  40

&&

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

$$

SHORT TERM...39
LONG TERM....26
AVIATION...39


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