Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 170807
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
407 AM EDT Thu Aug 17 2017



.SHORT TERM /Today through Friday/...

The upper ridge builds over the southeast today...keeping a very
warm air mass in place. Still no real triggers for convection except
diurnal heating so isolated to scattered thunderstorms can be
expected. Afternoon pops have been kept in the low chance range. A
front should sink into the TN Valley late tonight...so have held on
to low pops through the overnight hours for north and west areas.
Better chances for convection expected for Friday as the surface
boundary pushes into north GA.

Afternoon temperatures should again be very warm today. Nudged the
numbers up a degree or two especially for east central areas. This
puts heat index values 105 to 107 in a small area over the east
central counties for a couple of hours this afternoon. Too
borderline for a heat advisory. Suspect the dew points may mix out
to be lower than forecast. Also...any convection that develops could
affect these values.

17

.LONG TERM /Friday Night through Wednesday/...

A trough of low pressure will dig into the Great Lakes region to
start the Long Term, pivoting through Nova Scotia by late Sunday.
At the surface, a trailing front associated with the trough will
start to move through the region, eventually stalling across
central GA by Saturday afternoon. High pressure will build into
the northern half of the region through the remainder of the
weekend, before the front gradually lifts north Monday into
Tuesday. Another trough and surface front will approach from the
north by mid-week.

Expect residual scattered showers and thunderstorms Friday
evening well ahead of the surface front approaching from the
northwest. The front will cross the northern portions of GA
Saturday morning, eventually becoming stalled in central GA. This
will be the catalyst for thunderstorm development during the
afternoon and evening hours. With surface high pressure building
in from the north, the front remains stationary through Sunday,
perhaps shifting ever so slightly northward. This will once again
be the axis by which we see better coverage for convection during
the afternoon. The mid-level ridge starts to build back into the
region by early Monday with the surface high slowly moving off the
mid-Atlantic coast. So, while this isn`t typically the set up for
widespread convection, the stationary boundary will still be
enough convergence to generate thunderstorms by Monday afternoon.
This may wreak havoc for those wanting to witness the Solar
Eclipse. As it stands, it looks like the better cloud and
precipitation coverage will be along and south of I-20 as models
are trying to place the front in this general vicinity. However,
any little deviation in this surface feature or upper level
pattern could mean different cloud and precipitation coverage.
Based on the current model trends, the location that has the
lowest probability of precipitation and cloud coverage is across
the far northern tier of GA.

The ridge aloft will quickly break down by Monday night/Tuesday
morning as an upper trough dives down toward the Eastern CONUS.
Impulses in the mid-levels will allow for better coverage of
showers/thunderstorms Tuesday into Wednesday, especially across
the north.

Temperatures will be around normal through the period; albeit a
bit above normal Sunday with less clouds. Temperatures during the
eclipse (Monday) look to stay steady an hour before the maximum
obscurity (between 1pm-2pm), then drop a couple degrees up to 30
minutes after max obscurity (3pm). Temperatures are expected to
rebound quickly after the eclipse. The temperature drop will be
less for those under cloud cover/precipitation. This drop in
temperature should not impact the high temperature expected during
the afternoon.

26

&&

AVIATION...
06Z UPDATE...

Expect a VFR forecast through the period with diurnal cumulus.
Have included prob30 for the afternoon. Winds should remain on
the west side.

//ATL CONFIDENCE...06Z UPDATE...
High on all elements.

41

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          94  74  92  73 /  30  20  40  10
Atlanta         91  75  91  73 /  30  20  40  10
Blairsville     85  68  85  64 /  40  20  40   5
Cartersville    91  74  90  70 /  30  30  40   5
Columbus        93  76  94  76 /  30  20  40  20
Gainesville     91  74  90  71 /  30  20  40   5
Macon           94  75  94  75 /  30  20  40  20
Rome            91  74  90  69 /  30  30  40   5
Peachtree City  91  74  92  72 /  30  20  40  20
Vidalia         95  77  95  76 /  30  20  50  20

&&

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

$$

SHORT TERM...17
LONG TERM....26
AVIATION...17



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