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000
FXUS62 KFFC 280725
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
325 AM EDT Fri Jul 28 2017

.SHORT TERM /Today through Saturday/...
Early morning radar imagery reveals just a few nuisance showers
between ATL and MCN metros. Have not seen any lightning with this
activity the last few hours. Farther upstream...a larger complex of
showers and thunderstorms...associated with a weak 500mb vort max
was located across south central TN and northwest AL moving
southeast. This activity will begin to push into NW Ga in the next
few hours as the shortwave maintains its intensity. Could also see
some patchy areas of fog towards sunrise as dewpoint depressions
near zero.

Aforementioned vort max will be the main source of shower and
convective development this morning and into the afternoon. Deepest
moisture will reside across north Georgia so highest coverage
will generally be in this area. Model analysis of the synoptic
pattern reveals a robust shortwave across the Great Lakes...and
progged to move southeast towards DELMARVA through 00z sunday.
Southward movement of this disturbance will allow a sfc wave
initially along a cold front draped across the OH Valley to
become more organized as it begins to move eastward through WV and
eventually VA and off the Atlantic Coast. This movement will
allow the cold front to push through the CWA over the next 36
hours...a rather uncommon treat this time of year.

Although the aforementioned shortwave will initially produce
showers and storms over the area...focus will begin to shift
towards the front this afternoon and evening. With all this in
mind...southward building of mid/upper level cyclonic flow...along
with strengthening lower level westerly winds associated with the
sfc low to the north will easily allow for deeper layer shear to
approach the lower-mid 20s (kts). This combined with plentiful
moisture and instability should allow for the development of a
healthy mix of both loosely organized line segments and pulse
thunderstorms. Could see some severe activity with the primary
threat of very heavy rainfall and damaging winds/downbursts. Would
not be surprised to see SPC upgrade the area back to marginal or
even slight risk.

Activity could persist into Friday night with an overall weakening
trend. Front should be just south of ATL-AHN metro areas by 12z
Saturday. Some absolutely beautiful weather is store behind this
front (for July) as drier air moves into north Georgia.
Unfortunately central Ga will still see one more day of mainly
diurnally driven storms along the front/ perhaps a few strong/.
Mixing ratios behind the front are around 10g/kg with PWs under 1
inch-this is exciting!

Kovacik


.LONG TERM /Saturday Night through Thursday/...
Models continue in good agreement through the long term. The cold
front and associated short wave will continue to exit Saturday night
pushing the rest of the precip out of the CWA. It should dry over
the CWA Sunday through Tuesday as Canadian high pressure builds over
the Ohio Valley. Then as the next short wave drops into the mid
Mississippi Valley, the eastern trough broadens and the moisture
patterns become messy so have gone with climo for pops. Temps will
be at or just below normal through the long term.

17


&&

.AVIATION...
06Z Update...
Overall tranquil night expected with precip activity largely
dissipated. Some lingering mid level clouds across the state...and
could end up having some patchy areas of fog and perhaps some SCT
MVFR cigs towards sunrise. Through the day Friday expecting the
usual diurnal cu field to develop mid-late with increasing rain
and thunderstorm chances into the afternoon from north to south.
Some of the storms could become loosely organized into line
segments and carry a damaging wind threat through the evening.
Upon dissipation into the tomorrow night...will likely see some
MVFR/IFR cigs move in across northern TAF sites. Winds remain on
the west side and begin to pick up Friday afternoon between
10-15kts. Wind should remain elevated into Friday night between
7-10kts.

//ATL Confidence...06Z Update...
Medium on lower cigs and fog overnight tonight.
High on all other forecast elements.

Kovacik

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          89  72  88  67 /  60  50  20   5
Atlanta         87  72  86  68 /  70  50  20   0
Blairsville     79  66  81  59 /  70  50  20   5
Cartersville    84  71  85  65 /  70  50  20   0
Columbus        93  75  89  70 /  50  50  40   5
Gainesville     83  71  85  66 /  70  50  20   0
Macon           92  74  90  69 /  50  50  40   5
Rome            84  71  86  65 /  70  50  10   0
Peachtree City  87  72  87  67 /  60  50  20   0
Vidalia         93  75  88  71 /  50  50  60  20

&&

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

$$

SHORT TERM...Kovacik
LONG TERM....17
AVIATION...Kovacik