Area Forecast Discussion
Issued by NWS Atlanta, GA

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000
FXUS62 KFFC 250056
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
856 PM EDT Sat Oct 24 2020


.UPDATE...

Widespread rainfall and a few embedded thunderstorms have been
ongoing this evening ahead of a shortwave and attendant weak
surface low. The surface low is currently pushing northeast into
the Atlanta metro at this hour, migrating the heaviest rainfall
slowly northeast from the heart of the Atlanta metro into
northeast Georgia. Ongoing flash flooding issues in the Atlanta
area should gradually taper over the next few hours while the
focus for any additional isolated flash flooding concerns will
shift into northeast Georgia, especially with the aid of upslope
flow in the northeast Georgia mountains. By midnight or so, the
focus for heavy rainfall is expected to shift farther northeast
out of the forecast area.

RW

&&

.PREV DISCUSSION... /Issued 747 PM EDT Sat Oct 24 2020/

..00Z Aviation Forecast Discussion...

PREV DISCUSSION... /Issued 335 PM EDT Sat Oct 24 2020/

SHORT TERM /Tonight through Sunday Night/...

As expected surface cold front has essentially washed out. Area of
showers and thunderstorms moving into western portions of the
forecast area this afternoon associated with the short wave and its
surface reflection will steadily advance across the forecast area
overnight. Instability and shear remain fairly limited and chances
for severe thunderstorms appears to remain minimal. With the slow
progression of the precipitation across the area, localized heavy
rainfall is possible, however, widespread flood threat is expected
to remain minimal as well. Some lingering precipitation across
mainly the eastern half of the area tomorrow as atmosphere remains
moist and over-running sets up as surface high pressure builds in
from the northeast.

20

LONG TERM /Monday through Saturday/...

While guidance is in decent agreement with the evolution of the
majority of the midweek system, they diverge more late Thurs into
Friday and the Euro now has the slower progression with the upper
trough and also holds onto it longer as a cutoff low. The main
forecast concern though remains with how much rainfall and
shower/storm potential the area has for Wed/Thurs as the Gulf
tropical remnants gets phased in with the amplifying trough to the
west. Raised some pops accordingly given more consensus in this
period. Overall QPF has the storm total highest axis shifted
somewhat farther north than before and decently higher in the NE
CWA. For now have 3 to 3.5 inches in parts of north and west GA with
4 to 5 inches in the NE mtns. Previous discussion follows...

Baker

Previous...

LONG TERM /Sunday Night through Friday/...
Unsettled weather will prevail for much of next week. Models
continue to diverge beginning late Wednesday/early Thursday with the
end of the week system(s). Will continue to use the blend for these
periods.

Weak high pressure down the spine of the Appalachians will continue
Sunday night into Monday. A front will begin to approach the Lower
Mississippi River Valley on Tuesday, but models are not progging a
big southern push. The front eventually stretches more E-W and
becomes stationary over northern portions of the state by the middle
of the week.

Models begin to diverge significantly in the mid levels and at the
surface. Both models have an upper low moving across the southern
states for the latter half of the week, but the 12Z ECMWF is much
faster and stronger with the mid level system than the 00Z GFS. The
00Z GFS has weaker open wave moving across which is slower than the
12Z ECMWF. Regardless, SW flow aloft and at the surface will allow
for deep moisture to surge northward from the GOMEX Wednesday through
the end of the week...maybe in combination with a potential tropical
wave/disturbance. This could lead to some heavy rain ahead of the
frontal system. THe deep moisture should get scoured out by a
frontal boundary late Thursday/Friday, depending upon the model of
choice.

Drier air will settle behind the surface front during the first part
of the weekend.

NListemaa

AVIATION...
00Z Update...
Widespread shra/embedded tsra at ATL area sites will continue
progressing E into the overnight with tsra possible at AHN
through 04z or so. Sct shra at ATL sites expected through 06z
before tapering around 06z. Cigs/vsbys will deteriorate with
MVFR cigs likely by around 02z and IFR/LIFR cigs likely after 06z
through 15-17z before improvement back to MVFR. Low-end VFR
possible after 20-22z. Winds initially NW/W will be light and
variable to near calm overnight then light and westerly through
20-22z at which point a shift back to E is possible.

//ATL
Confidence...00Z Update...

Low to medium on winds.
Medium on other elements.

RW

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          63  75  61  73 /  70  30  20  10
Atlanta         63  75  62  74 /  70  20  10  10
Blairsville     58  71  57  70 /  60  30  20  10
Cartersville    62  76  62  77 /  60  20  10  10
Columbus        65  79  64  81 /  60  10   5   5
Gainesville     62  73  61  71 /  70  30  20  10
Macon           64  79  62  81 /  70  20  10   5
Rome            61  76  62  77 /  50  20  10  10
Peachtree City  63  76  62  76 /  70  10  10   5
Vidalia         67  81  66  82 /  60  30  10   5

&&

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

$$

SHORT TERM...RW
LONG TERM....Baker
AVIATION...RW


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