Area Forecast Discussion
Issued by NWS Atlanta, GA

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FXUS62 KFFC 231341
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
941 AM EDT Sun Apr 23 2017



.UPDATE...
A cold front will continue to push south through much of GA today.
Currently a wave of low pressure is moving along the boundary
across far north GA. Regional radar shows widespread precipitation
associated with this system across the north and western portions
of the CWFA. Think only isolated thunder is possible for the next
few hours. For the afternoon, do think the best chances for
thunderstorms will be in the areas that have remained free of
thick cloud cover this morning (especially along and east of
Interstate 85). Scattered strong storms will be possible, with
potential for an isolated severe thunderstorm. The primary modes
of severe weather would be wind gusts up to 60mph and hail up to
an inch. Thunderstorms would also be capable of producing locally
heavy rainfall.

&&



.PREV DISCUSSION... /Issued 731 AM EDT Sun Apr 23 2017/

PREV DISCUSSION... /issued 350 AM EDT Sun Apr 23 2017/

SHORT TERM /Today through Monday/...
Latest surface analysis across the area shows low pressure over
North Alabama and North GA at this hour. Frontal boundary extends
from this feature through Southern Alabama and Mississippi and
into the Gulf of Mexico although the most significant of the drier
and cooler air resides further upstream over the Tennessee and
Mississippi Valleys. At the upper levels...closed upper low just now
entering the Tennessee Valley and continuing to strengthen as it
drops SE. Continue to see showers and isolated thunderstorms stream
across the area from time to time with most of the TSRA of the
elevated variety given surface CAPE values near zero.

Through the remainder of the morning hours...strengthening
approaching upper low will allow for a stronger diffluent pattern
o develop maximizing lift by 15Z. If we were a bit more
unstable...then concern would be higher across the North given
shear values but an abundant of low clouds should keep activity
benign there. Could get more interesting to the south where CAPE
values will increase to 1000 to 1500 J/KG by the afternoon hours.
Although shear not quite as high...could still see some isolated
strong to severe storms with strong gusty winds and modest hail
potential given continued cold temps aloft.

Low moves east of the area through tonight but even into
Monday...models continue to show some weak instability in the wrap
around environment. Would not be surprised to see some additional
small hail reports Monday afternoon given 500mb temps approaching
-18C.

As far as rainfall is concerned...already seen an inch to close to
an inch and a half from Rome to Cleveland and points northward.
Anticipate another inch and a half to almost 2 over the same areas
but with enough time displacement to preclude any significant
flood potential. Only isolated flood issues anticipated and will
forego any flood watches for now.

Deese

LONG TERM /Monday Night through Saturday/...
All of the activity during the short term period will be pushing
east out of the CWA by the beginning of the long term forecast
period on Monday night. The slow moving closed H5 low will be
centered in the vicinity of Georgia and SC coastline...with
associated sfc low centered just downstream off the NC/SC coastline.
Wrap-around shower activity associated with this system will be
mainly confined to eastern counties and should gradually push east
through the overnight hours...leaving the CWA dry with mid level
heights beginning to rise.

Tuesday and Wednesday look to be very dry and pleasant as a weak mid
level shortwave ridge builds in and weak high pressure takes over at
the surface. Could see some lingering lower level cloud cover
Tuesday...but temps should begin to rebound with highs upper 70s to
low 80s Tues and mid-upper 80s Wednesday.

The weak shortwave ridge will begin to shift to the east of the
region late Wednesday into Thursday. Upstream pattern shows an
elongated trough building into the Western and Central US...with
several notable embedded shortwave troughs responsible for the
development of numerous sfc waves along a frontal boundary. This
frontal boundary will push toward the CWA early Thursday.
Deterministic models begin to diverge somewhat around this
time...but both agree the front will stall across the state by
Thursday night...which makes sense given large displacement from
parent system. Plenty of instability should allow for thunderstorm
development in the vicinity of this boundary...but weak shear argues
against robust organization at this time.

00z EC came more in line with 00z GFS tonight with a broad mid level
closed low developing within the broad cyclonic flow across the
Western/Central US...which is also now being reflected in the
ensemble data. Given this solution...strong cyclogenesis should take
place in the lee of the Rockies next weekend. This should kick the
stalled boundary across our area north as a warm front as it moves
east into the Midwest/Great Lakes... with the associated cold
front expected to approach the area at the end of the long term.

Kovacik

AVIATION...
12Z UPDATE...

Looks to be a challenging aviation forecast day with low pressure
remaining initially over NW GA and slowly transitioning eastward.
This will bring multiple rounds of precipitation to the terminals
but the most significant between 15Z and 19Z to most of the
terminals. The models do differ significantly on this window with
some showing an onset time as late as 18 to 19Z. Will favor the
earlier start time for now and adjust as system gets closer. IFR
will accompany the potential for storms and be persistent through
the afternoon hours. May get a brief break to MVFR late this
afternoon into evening but expect re-formation later Sunday night.

//ATL CONFIDENCE...12Z UPDATE...

Medium on TSRA onset.
High on remaining elements.

Deese

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          73  54  66  54 /  90  90  40  30
Atlanta         70  55  68  56 /  90  60  30   5
Blairsville     62  50  66  51 /  90  80  40  10
Cartersville    67  54  69  54 /  90  60  20   5
Columbus        73  54  71  56 /  70  40  10   0
Gainesville     65  53  67  55 /  90  80  40  20
Macon           79  54  69  55 /  80  70  20   5
Rome            67  53  72  53 /  90  60  20   5
Peachtree City  71  53  67  53 /  80  50  20   5
Vidalia         85  60  72  57 /  70  70  40  20

&&

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

$$

SHORT TERM...
AVIATION...


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