Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 230206
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
1006 PM EDT Thu Jun 22 2017

.UPDATE...

A busy and challenging night that included what seemed like at
times a little bit of tropical, some supercell, and even a dash
of QLCS thrown in. All this was made possible by extremely high
PWs in place nearing 2.5 inches to start the day, a frontal
boundary draped across the Northern metro, and a late developing
surge of dry mid level air from the south. That dry air allowed
for a progressive line to form with isolated damaging wind gusts
along its leading edge. This complex will exit within the next
hour and really not much in its wake forecast by the hi res for
the remainder of tonight. Still some residual CAPE and certainly
plenty of moisture around so will keep low end chance in for
mainly the NW tier.

&&

Deese

&&

.PREV DISCUSSION... /issued 827 PM EDT Thu Jun 22 2017/

PREV DISCUSSION... /issued 320 PM EDT Thu Jun 22 2017/

SHORT TERM /Tonight through Friday Night/...
Main forecast concern will be initially here in the near term as the
environment has shown some rapid destabilization with the extremely
tropical airmass in place as the low cloud deck has been scattering
quickly from the south given being in the warm sector of Cindy`s
remnants. Convective bands streaming in from the south fueled by a
steady strong moisture advection off the Gulf will have about 2000-
3000 J/kg of SBCAPE to attain, albeit tall/skinny in profile. The
issue will be with both the PWATs being close to 2 inches and
enhanced area of helicity rich low levels just starting to impinge
upon the western border of the CWA. Some 250 m2/s2 of 0-1 km SRH
will be bothersome for isolated quick spin-up tornado potential in
our western tier from late afternoon here into the evening. Also
given the aforementioned PWATs, any stronger convection will have
high precip efficiency and training of cells could bring flash flood
potential. It`s not a welcomed sight to see temps of upper 80s/low
90s over dewpts in the mid to upper 70s advecting into the area.

The deeper moisture field and orientation of Cindy`s dynamics should
continue to phase with an upper shortwave more to the NW by late
tonight into Friday. Expecting a lull in shower/storm coverage
mainly after midnight tonight as chance to likely pops stay more
orientated to the far NW and TN Valley. Could have a similar type of
convective threat for northern portions of the area by Friday
afternoon (given progged instability/low level shear parameters) and
then be more progressive to the SE with the evolution of the
shortwave and translated sfc front late Friday night into Saturday.
Tailored likely to categorical pops with this feature accordingly
across north GA. Will be rather gusty out of the SW ahead of this as
well.

Temp wise, a bit more diurnal range expected Friday with more areas
reaching highs close to climo in the upper 80s to low 90s (less
morning cloud coverage expected).

Baker

LONG TERM /Saturday through Thursday/...
The remnants of Tropical Storm Cindy will finally be out of our hair
at the beginning of the long term forecast period on saturday
morning. However there will be a cold frontal boundary moving south
across the area. Rain and thunderstorms will be ongoing along the
front...enhanced by diurnal heating in the afternoon. There looks to
be enough deep layer shear /0-6km of 20-30kts/ as a broad trough
deepens across the eastern 2/3rds of the US to work in conjunction
with instability invof the front. This should allow for some
organization of thunderstorm clusters along the front. The main
threat will be damaging wind gusts. SPC has a large majority of
central and eastern Georgia in a marginal risk.

The front will make slow progress into central Georgia Saturday
evening into the overnight hours but the loss of daytime heating and
rather poor forcing should allow most activity to gradually
dissipate. Front looks to linger across far southern zones on Sunday
where again diurnal heating should allow for a gradual increase in
thunderstorm activity through the afternoon. Shear appears to be
displaced too far north to pose a notable severe threat by this
time. Can`t rule out isolated stronger storms...but think Saturday
has better parameters than Sunday.

Front should clear the CWA by Monday. A rather unseasonably
strong area of sfc high pressure will gradually build into the
region from the north in the wake of the front...which will make
for a dry day. A strong shortwave rotating around the broad scale
trough over the eastern US will likely bring some clouds to area
on Tuesday...but thinking large dome of sfc high pressure will
keep things dry. Height rises in the mid level behind this
shortwave combined with sfc high pressure should make for a very
pleasant Wednesday. Will see moisture gradually return outside of
the extended as the sfc high begins to scoot off the Atlantic
Coast.

Kovacik

AVIATION...
00Z UPDATE...

Main cluster of SHRA/TSRA now shifting east of all the terminals
except AHN where activity will persist just a little longer.
Model guidance actually much more optimistic wrt cigs overnight in
both coverage and cloud heights. However...with such saturated
conditions of late...will lean toward persistence and previous
forecast of some developing MVFR cigs tonight. Otherwise...drier
air working in for Friday but still enough moisture to warrant
continued Prob30 for most sites.

//ATL CONFIDENCE...00Z UPDATE...

Medium for cigs tonight.
High for remaining elements.

Deese

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          71  90  73  85 /  90  30  60  70
Atlanta         72  87  73  83 /  30  40  70  70
Blairsville     67  83  68  79 /  70  60  80  70
Cartersville    72  87  72  83 /  30  60  80  70
Columbus        74  90  75  86 /  30  20  40  60
Gainesville     70  86  72  82 /  80  40  80  70
Macon           73  91  74  88 /  90  20  30  40
Rome            72  87  72  84 /  30  70  80  70
Peachtree City  71  88  72  84 /  30  30  60  60
Vidalia         75  91  75  91 /  40  40  20  30

&&

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

$$

SHORT TERM...Deese
LONG TERM....01
AVIATION...Deese



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