Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 221904
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
304 PM EDT Tue May 22 2018

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

An increasingly moisture laden environment combined with mid
level low over Alabama is combining to produce numerous showers
and scattered thunderstorms this afternoon. Anticipate both
coverage and intensity of storms to increase through late
afternoon and evening although strong storms looks to be the upper
limit in this environment. Of more concern will be the increased
rainfall rates and potential for training echoes leading to
enhanced flash flood potential. This potential should be
maximized over west central GA where WPC has targeted an area for
2 inch per hour rates through this afternoon.

In this type of environment, the rain really never fully comes to
an end and expect convective chances to continue into the
overnight period although should see some reduced coverage with
the arrival of low clouds along and north of I85. Could make a
case for mainly showers after midnight but for now kept it easy
and just went continued chance thunder overnight.

If anything, deep layer moisture will increase on Wed with
precipitable water approaching 2 inches. Will still be dealing
with mid level low as well with models varying with its position
but keeping over the forecast area. Focus will be for central GA
and have highest pops there but really just about anyone could see
some brief stint with heavy rainfall with this setup. A little
bit of question as to how much low clouds will lift on Wed and
this could limit amount of instability although wont take much at
all to get showers going.

Deese


.LONG TERM /Thursday through Tuesday/...

Main focus continues to be on the potential for a tropical low
getting more organized into the weekend. NHC continues to have a 40
percent chance of formation and guidance is at least in consensus of
a low of some semblance, though now some solutions are a bit less
progressive and vary in location of the center. Regardless of the
differences in this feature, what`s more certain is daily rounds of
efficient rain producers and isolated flash flooding potential given
this ever persistent tropical airmass. Made a few minor adjustments
to raise chance to likely pops a few periods (Friday day and
Saturday night), then just a refresh of other elements given the
latest blend. WPC QPF is coming in a bit higher especially across
central GA... now with storm totals of closer to 4-5 inches.
Previous discussion follows...

Baker

Still no drying period in site for the local area through the
extended. Beginning the period at 00z Thursday...evidence of the
short term`s weak mid level low across the state is beginning to
become very diffuse though there is still clear evidence of some
enhanced mid level moisture across the area. This area of enhanced
moisture will become trapped under a mid/upper level ridge that
encompasses much of the eastern US from the Plains to the OH
Valley. This may allow for some lingering showers to survive into
at least part of Wednesday night. This enhanced area of moisture
will linger through the day Thursday and provide a focus for
convection by the afternoon as parcels become more buoyant in
conjunction with daytime heating. Similar to Wednesday
night...isolated showers may continue into the overnight on
Thursday into early Friday.

By Friday...things begin to become slightly more interesting. The
aforementioned area of enhanced mid level moisture may become pushed
northward slightly into north Georgia as a deep push of tropical
moisture enters the Gulf from the Caribbean. This will continue the
chance for mainly diurnally driven convection across the area but
especially north Georgia. The wave of deep tropical moisture from
the Caribbean is still expected to take on some type of circulation
tho the amount of organization and strength is not quite clear yet.
Per latest forecast from NHC...this wave/mid level perturbation has
a 40 percent chance of developing some degree of subtropical or
tropical characteristics. Although it is often difficult to not
focus primary attention on whether or not this wave will become a
named storm...the main focus should be on the potential threat for
additional [heavy] rainfall amidst an already damp environment.
Given that thus far the consensus is for this feature to remain
stationary near the Gulf Coast...this creates an endless open road
for waves of deep tropical moisture to enter Georgia through at
least the weekend. Should trends continue such as they have the
previous few days...flooding concerns will undoubtedly increase.

This feature looks to linger across the region through the remainder
of the long term and even outside of the long term through the
middle of next week.

Kovacik

&&

.AVIATION...
18Z UPDATE...
Passing SHRA for most of the terminals thus far today but things
beginning to quickly change, especially for MCN. There, TSRA
continues to develop just south of the terminal and should affect
for the next couple hours. Delayed start to TSRA for the remaining
terminals with TEMPO time now slated for 20Z to 24Z. Low clouds to
return for the overnight period with IFR for all but MCN included
with this set. prob30 for ATL for Wed afternoon as new storms
develop in a similar environment to today.

//ATL CONFIDENCE...18Z UPDATE...
Medium of TSRA chances and timing.
High on remaining elements.

Deese

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          66  81  67  82 /  60  50  50  60
Atlanta         68  79  68  82 /  60  60  60  60
Blairsville     62  79  61  80 /  50  50  50  40
Cartersville    66  81  66  84 /  60  50  40  50
Columbus        69  82  69  84 /  60  70  70  60
Gainesville     66  79  67  81 /  60  50  40  40
Macon           68  82  68  83 /  60  60  60  70
Rome            67  84  67  85 /  50  50  40  40
Peachtree City  67  80  67  83 /  60  70  70  60
Vidalia         69  84  70  85 /  50  60  60  60

&&

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

$$

SHORT TERM...Deese
LONG TERM....Baker
AVIATION...Deese


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