Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 051916
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
216 PM EST Mon Dec 5 2016

.SHORT TERM /Tonight through Tuesday Night/...
An upper low across SW TX will lift NE through the period, merging
with an upper trough swinging through the upper mid-west. Meanwhile,
an associated sfc low off the Louisiana coast will lift north and
west of the area through Tuesday afternoon. This will bring an
increase chance of precipitation as we approach the evening hours,
with the heaviest expected overnight and into the early morning
hours Tuesday. With a high to the north and the wedge currently in
place across much of north and central GA, this will inhibit storm
development through the afternoon/early evening. However, we did
note lightning strikes across AL and thus placed much of the area in
SCHC thunder by the evening hours. The wedge will retreat to the NE
as a warm front trapped across southern GA lifts north. However, the
extent of the northward progression of the front is still a bit
unclear. Confidence is increasing that the front will lift across
central GA Tuesday morning (perhaps approaching north GA) as the sfc
low exits to the north. It should also be noted that as the wedge
retreats and the front approaches, the gradient will tighten with
winds becoming gusty at times. While instability is still marginal
with ample shear, we can not rule out strong to isolated severe
storms possible as we get into later this evening, overnight and
into the morning hours Tuesday (especially across central GA). High
pressure will build into the area late Tuesday allowing things to
dry out fairly rapidly. Also, anticipate gusty westerly flow Tuesday
afternoon behind the low.

Latest WPC and model guidances are suggesting the heaviest rainfall
axis will set up south of the I-85 Corridor where rainfall amounts
of 1 to 3 inches are possible over the next 24 to 36 hours. These
amounts over this area should not be enough to cause any significant
flood concerns at this time, but if the heaviest rainfall axis
shifts northward, cannot rule out some brief minor flooding along
any of the typical flood prone creeks in the Atlanta area.

An atypical diurnal temperature pattern will set up tonight as the
wedge retreats and the warm moist air to the south lifts north. This
will mean increasing temps through the overnight.  Lows occurring
early in the evening in the mid 50s across the north to around 60
along central GA.  Temps will continue to increase Tuesday with
highs around 60 across the higher elevations to the lower 70s down
toward central GA. With the low to the north of the area and NW flow
bringing in drier and cooler air Tuesday night, expect temps to fall
quickly with lows in the low/mid 40s across north GA and upper 40s
further south.

26

.LONG TERM /Wednesday through Monday/...
Only tweaks to the long term based on the latest guidance.

BDL

PREVIOUS DISCUSSION...
Medium-range models remain in general agreement concerning the large
scale pattern through the extended forecast period...however there
continues to be noticeable differences between the GFS and ECMWF
concerning the timing and depth of the smaller scale details. With
this in mind I have continued the trend of generally going with a
blend through the period. Still looking at a major cold intrusion
behind the Wednesday/Thursday system. Precipitation is expected to be
over by the time the better cold advection overtakes the region and
no wintry precipitation is included in the forecast for the mid/late
week system at this time. Both the GFS and ECMWF are a bit slower
with the onset of precipitation associated with the weekend system.
Blended POPs do not move into the northwest until late Sunday
allowing for more of a warm up. Latest temperature forecasts
Sunday night into Monday point to a liquid event at this time.

20

&&

.AVIATION...
18Z Update...
A mix bag of reduced vsbys/cigs will continue through the next
couple of hours as rain fills in. Vsbys/Cigs will drop back down
later this afternoon through much of the remaining TAF period. The
next round of rain will start to move into the area this
afternoon with the heaviest expected to be overnight into the
early morning hours. Did add PROB30 for TSRA as instability
increase tonight into early tomorrow. East winds through Tuesday
morning may gust ahead of the warm front early Tuesday morning.
Winds eventually becoming SE and then SW as the low lifts north.

//ATL Confidence...18Z Update...
High on all elements.

26

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          51  59  44  61 / 100 100  10   5
Atlanta         52  68  45  59 / 100 100  10   5
Blairsville     50  58  39  56 / 100 100  10  10
Cartersville    53  65  42  57 / 100 100  10  10
Columbus        57  70  48  62 / 100  80  10   0
Gainesville     50  57  44  58 / 100 100  10  10
Macon           55  71  47  64 / 100 100  10   0
Rome            53  63  41  57 / 100 100  10  10
Peachtree City  54  67  43  60 / 100 100  10   0
Vidalia         59  77  51  67 / 100  80  10   0

&&

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

$$

SHORT TERM...26
LONG TERM....BDL
AVIATION...26


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