Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 231939
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
339 PM EDT Tue May 23 2017


...Tornado Watch continues for portions of east central Georgia
until 6 PM and Flash Flood Watch for majority of area except far
north Georgia through Wednesday afternoon...

.SHORT TERM /Tonight through Wednesday Night/...

Latest wave of showers/tstorms slowly exiting the CWA and by this
evening this area of showers/tstorms will have pushed east out of
the region. With instability remaining over the CWA tonight will
need to keep low end chance pops for showers/tstorms all areas. The
next wave of precip will be along and ahead of the cold front late
tonight and Wednesday. Models have waffled a bit on timing of this
front and precip but general consensus is that a line of
showers/tstorms will develop along and head of the front, moving
into northwest by between 10 and 12z, moving rapidly across the CWA
and by mid afternoon Wednesday this round of showers/tstorms will be
east of the region. CAPES will be 1000+ at 12Z ahead of the cold
front along with 60kts bulk shear. With the forced lifting of the
front, this should be enough for a few storms to become severe with
gusty winds and possibly a QLCS tornado as the line moves across the
CWA.

The H5 low will be dropping into the Tennessee Valley Thursday
evening with very cold air aloft (-20 to -22C at H5 which is quite
cold for this time of year). This will continue to keep the
atmosphere destabilized as evident by the +100 CAPES on all models
Wednesday night. Will need to increase pops across north GA
Wednesday night and with the very cold temps aloft, there is the
risk of small hail with any thunderstorm.

17

&&

.HYDROLOGY...

Forecast QPF through 00Z Thursday should remain less than an inch,
however can`t rule out an isolated 1 to 2 inch amount in some of the
heavier thunderstorms. With the previous 2 days of rainfall, flash
flooding remains a possibility with the next wave of precipitation
late tonight and Wednesday. Will therefore continue the Flash Flood
Watch through 18Z Wednesday.

17

&&

.LONG TERM /Thursday through Tuesday/...

Made minor cosmetic changes to fcst mainly to limit some precip
chances in the north for a quicker departure of the upper
low/moisture by Thursday evening. Also expanded Saturday slight
chance pops for north GA given the zonal flow/disturbance
influence. Otherwise rest looks on track with neighboring offices
and previous discussion follows...

Baker

PREV DISCUSSION... /issued 351 AM EDT Tue May 23 2017/

LONG TERM /Wednesday Night through Monday/...

Much of the area will be on the backside of deep moisture plume and
associated cold front by Wednesday night with anomalously cold upper
level low approaching from the northwest. Breezy and much cooler
conditions will prevail into Thursday with clouds and scattered
showers across north Georgia. Lapse rates appear steep enough to
support a few embedded thunderstorms, again mainly north of I-20.
Small hail will be possible with any storms. By late Thursday into
Thursday night, drier air will work across the area and any
showers/storms will diminish.

Temperatures will gradually moderate closer to normal Friday into
the weekend as an upper level ridge over the Gulf of Mexico builds
slowly north. Battle between the GOM ridge and a strong upper trough
digging across the Northern Plains/Upper Midwest occurs over the
weekend creating an increasingly zonal flow across the area,
especially north GA. Moisture will begin to increase as this occurs
with chances for rain picking up late Saturday into Sunday. Medium
range models appear to deepen longwave trough across the eastern
CONUS thus resulting in an extended period of rain setting up once
again - Sunday into Monday - across the Southeast region. However,
this is 5 to 6 days out and things will likely change.

DJN.83

&&

.AVIATION...
18Z Update...
Current wave of showers/tsra moving across central/east GA will
end from the west this afternoon with scattered showers remaining
through the rest of this afternoon and evening elsewhere. A squall
line is expected to develop along a cold front and move into
western GA late tonight/early Wednesday and spread across the
forecast area through the morning hours, exiting to the east by
18Z Wed. Mostly VFR with scattered MVFR/IFR cigs will hold through
this evening with widespread IFR/MVFR cigs by 06z Wed. Cigs will
remain IFR/MVFR through 18Z Wed.

//ATL Confidence...18Z Update...
High on winds.
Low to medium on remaining elements.

17

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          63  75  57  73 /  30  80  40  20
Atlanta         65  73  56  71 /  50  90  30  20
Blairsville     60  69  52  66 /  50  90  60  40
Cartersville    64  74  55  72 /  60  90  50  30
Columbus        66  77  57  76 /  60  90  20   5
Gainesville     63  73  56  69 /  40  90  50  20
Macon           67  77  57  76 /  30  80  20  10
Rome            63  72  54  72 /  70  80  60  30
Peachtree City  65  75  56  72 /  50  90  20  10
Vidalia         69  79  61  77 /  70  80  30  10

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Wednesday afternoon for the following
zones: Baldwin...Banks...Barrow...Bibb...Bleckley...Butts...
Carroll...Chattahoochee...Cherokee...Clarke...Clayton...Cobb...
Coweta...Crawford...Crisp...DeKalb...Dodge...Dooly...Douglas...
Emanuel...Fayette...Forsyth...Glascock...Greene...Gwinnett...
Hall...Hancock...Haralson...Harris...Heard...Henry...Houston...
Jackson...Jasper...Jefferson...Johnson...Jones...Lamar...
Laurens...Macon...Madison...Marion...Meriwether...Monroe...
Montgomery...Morgan...Muscogee...Newton...North Fulton...
Oconee...Oglethorpe...Paulding...Peach...Pike...Polk...Pulaski...
Putnam...Rockdale...Schley...South Fulton...Spalding...Stewart...
Sumter...Talbot...Taliaferro...Taylor...Telfair...Toombs...
Treutlen...Troup...Twiggs...Upson...Walton...Warren...
Washington...Webster...Wheeler...Wilcox...Wilkes...Wilkinson.

Tornado Watch until 6 PM EDT this evening for the following
zones: Emanuel...Jefferson...Johnson...Laurens...Montgomery...
Telfair...Toombs...Treutlen...Washington...Wheeler...Wilkinson.

&&

$$

SHORT TERM...17
LONG TERM....DJN.83/Baker
AVIATION...17



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