Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 231135
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
735 AM EDT Fri Jun 23 2017



.PREV DISCUSSION... /Issued 352 AM EDT Fri Jun 23 2017/

SHORT TERM /Today through Saturday/...

Airmass remains very tropical in nature across the CWFA. Convergence
zone has set up across the far NW CWFA this morning, and light to
occasionally rainfall will continue to fall this morning. So, far
rainfall amounts have been fairly light, but continued rainfall will
serve to help saturate the ground.

The remnants of Cindy will push eastward, and interact with shear
axis/weak convergence boundary through Saturday. This shear
axis/weak convergence zone will slowly sag south across the CWFA
through Saturday, serving to focus areas of precipitation.

Speaking of saturated ground, heavy rainfall has fallen across the
metro area and Interstate 20 corridor over the last week. As the
remnants of Cindy move east and interact with the weak
boundary/shear axis, today through early Saturday, additional
locally heavy rainfall is likely. Training storms would be the most
likely culprit, but a few strong thunderstorms could also develop
and produce locally heavy rainfall. Will be issuing a Flash Flood
Watch for roughly the Interstate 20 corridor and northward through
Saturday. Even though the far NE mountains haven`t received as much
rainfall over the last week as some areas, do think some localized
flooding is possible...and the complex terrain does increase the
potential.

As with any tropical system, the potential for severe weather will
exist. Especially for isolated tornadoes within any rainbands. Areas
roughly along and west of the Interstate 85 corridor will have the
best potential for any severe weather through tonight. However, if
good heating occurs across the southern CWFA today, an isolated
severe thunderstorm isn`t out of the question either. In addition,
the coverage of storms should be less down south - with the only
focusing mechanisms for precip would be mesoscale boundaries or
differential heating boundaries.

The axis of heavier rainfall begins to shift southward on Saturday.
Areas mainly south of Interstate 20 haven`t seen as much rainfall in
previous days, so additional watches are not likely at this time.

NListemaa

LONG TERM /Saturday Night through Thursday/...

A welcome change is headed our way in the long term as drier air
moves into the region.

The remnants of TS Cindy will continue to kick out to the north
and east with some residual moisture hanging along a cold front
that will push south Saturday night into Sunday. Anticipate
shower/thunderstorm activity to dwindle through the overnight into
early Sunday given loss of day time heating and upper level
support. The front will eventually sag south of the area with much
of the precipitation activity confined to the far southern
portion of the CWA. Thus anticipate diurnally driven thunderstorms
Sunday afternoon across this region. The front will eventually
wash out with strong high pressure building into the area for the
beginning of next week. The surface high will eventually shift
across the mid-atlantic and then out to sea by Thursday. Return
flow will usher in a bit more moisture into the region with
temperatures slowly on the increase. This will mean higher
diurnal thunderstorms coverage, especially by next Friday.

Given cooler high pressure and a much drier airmass moving in,
temperatures will be below normal...feeling quite pleasant.

26

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

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...
12Z Update...
Some sct IFR clouds around this morning with ovc VFR. Cigs should
be bkn vfr this afternoon. Do think most shra/tsra will stay well
to the north and west of ATL through the evening hours when a
boundary begins to set up over the metro area for several hours.
More widespread light shra expected after 06z. Precip will taper
off by later Saturday. Winds will remain on the west side with a
few gusts to around 20kt this afternoon.

//ATL Confidence...12Z Update...
Medium confidence all elements.


&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          89  73  85  69 /  30  60  60  20
Atlanta         88  73  82  68 /  40  70  70  20
Blairsville     83  67  79  60 /  60  80  60   5
Cartersville    87  72  82  65 /  60  80  70  10
Columbus        91  75  86  72 /  20  50  60  30
Gainesville     86  72  82  67 /  50  70  70  10
Macon           91  74  87  72 /  20  30  60  30
Rome            87  72  83  65 /  70  90  60  10
Peachtree City  88  73  83  68 /  30  60  70  30
Vidalia         92  75  91  74 /  40  20  50  30

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch from 2 PM EDT this afternoon through Saturday
evening for the following zones: Banks...Barrow...Bartow...
Carroll...Catoosa...Chattooga...Cherokee...Clarke...Clayton...
Cobb...Coweta...Dade...Dawson...DeKalb...Douglas...Fannin...
Fayette...Floyd...Forsyth...Gilmer...Gordon...Gwinnett...Hall...
Haralson...Heard...Henry...Jackson...Lumpkin...Madison...
Murray...Newton...North Fulton...Oconee...Oglethorpe...
Paulding...Pickens...Polk...Rockdale...South Fulton...Towns...
Union...Walker...Walton...White...Whitfield.

&&

$$



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