034 
FXUS62 KFFC 091946
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
246 PM EST Mon Nov 9 2020

...Afternoon Area Forecast Discussion for Nov 9...

.SHORT TERM /Tonight through Tuesday Night/...

The short term period will be marked by the effects of Eta in the
eastern Gulf of Mexico and high pressure centered off the Eastern
Seaboard. This setup will promote continued easterly flow and 
deep moisture advection across the CWA. Today, isolated showers 
are expected mainly across the southern and eastern portions of 
the CWA, where the greatest moisture is focused. Models are 
progging a slug of tropical moisture to push into the CWA from the
southeast on Tuesday, so PoPs are forecast to increase from 
slight chance to chance area-wide over the course of the day. PoPs
will further increase to likely overnight Tuesday into Wednesday 
for much of north Georgia, aided by ascent associated with an 
approaching trough from the west. Highs and lows will be well 
above-average through the period.

Martin


.LONG TERM /Wednesday through Monday/...

Uncertainty continues into the long term thanks in large part to 
Tropical Storm Eta and how long the storm plans to stick around in
the Gulf of Mexico. Regardless of whether or not the core of the 
storm does track over us, we do expect moisture from the storm to 
impact the CWA and bring potentially heavy rainfall to the CWA, 
especially in some of the higher terrain.

Eta is expected to begin moving to the north Tuesday night after 
stalling near the western tip of Cuba for most of the day. This 
northward movement is in response to a large upper level trough 
and embedded shortwave that ejects out of the SW CONUS and begins 
to move to the NE. This is also expected to help break down the 
subtropical ridge that been guiding Eta as of recent, allowing Eta
to pulled into that northward movement. The line between whether 
or not Eta is pulled into that ejecting trough is very fine. There
is some significant bifurcation within the forecast models, with 
most recent runs of the Euro and EPS bringing the storm to the 
north until it is quickly wiped out by shear associated with the 
trough, while recent runs of many others, including the GFS and 
many members of the GEFS, don't quite pull the storm into the 
trough, leaving it behind to meander in the Gulf for a few days 
before finally dissipating. This latter scenario would likely 
keep the frontal system that is associated with the upper level 
trough from completely clearing the area, and also would leave the
large well of moisture associated with Eta mostly intact and able
to be drawn upon for potential additional rainfall into the 
latter part of the week.

Tuesday night is progged by most of the models to when rainfall 
amounts begin to really pick up across the CWA. A cold front 
begins to approach the CWA from the west overnight into early 
Wednesday morning as the associated surface low moves across the 
midwest. This will allow for a strong southerly fetch that begins 
to draw moisture from Eta into the area and allow for the 
development of some light to moderate showers across the CWA. As 
the cold front approaches the area on Wednesday, it should provide
stronger vertical forcing and a focus for moisture convergence 
that will allow for some heavier precipitation rates into early 
Thursday. The overall southerly to even southeasterly fetch will 
also need to be monitored in the mountains of NE GA, as orographic
lift may provide for some potentially significant enhancement to 
rainfall amounts in that area. The cold front will begin to weaken
and stall as it moves into the CWA as the upper level forcing 
rapidly moves away to the northeast.

Where Eta goes and how far into the CWA the weakening cold front 
is able to travel will determine impacts from here. The upper 
level pattern is pretty progressive with several shortwaves 
quickly passing to the north of the CWA and providing some chances
for showers through the weekend. If Eta is still around in the 
Gulf, it could provide for some additional moisture that could 
lead to better PoP chances that are advertised in the GFS and some
members of the GEFS from Thursday through the weekend. The best 
chance next chance of precip looks to be Saturday, where PoPs have
been bumped up a little bit in comparison to the blend, 
especially across north GA. No matter what, these quickly passing 
systems will allow warmer, moister area from the south to quickly 
move back into the area, squashing any hopes you may have had of 
feeling another taste of winter any time soon. But I will leave 
you with some hope, colder weather fans - by the end of the long 
term, there are signs of more significant cold front moving 
towards the area that could finally bring another shot of cold air
to the area.

Lusk


&&

.AVIATION...
18Z Update...
MVFR cigs will transition to VFR through 22z. Isolated showers will 
be possible mainly across the southern and eastern portions of the 
forecast area this afternoon and evening. Easterly winds 5-15 kt will
persist through the period, with periodic gusts tonight and 
Tuesday. Cigs will be the main focus tonight through tomorrow. 
IFR cigs are in the forecast starting around 08z and remain in 
the forecast through Tuesday. Some areas of LIFR will be possible,
but did not feel confident enough to include in the TAFs.

//ATL Confidence...18Z Update...
Medium to high confidence on cigs.
High on all other elements.

Martin


&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          64  75  68  77 /  20  50  70  80 
Atlanta         65  74  68  76 /  20  50  60  80 
Blairsville     59  72  64  72 /  20  50  70  80 
Cartersville    64  76  67  77 /  20  50  70  80 
Columbus        69  80  71  81 /  20  40  40  70 
Gainesville     63  72  66  75 /  20  50  70  80 
Macon           68  81  70  82 /  20  50  40  70 
Rome            64  77  68  78 /  10  50  70  80 
Peachtree City  65  76  69  78 /  20  50  50  80 
Vidalia         70  82  72  82 /  20  50  50  60 

&&

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

$$

SHORT TERM...Martin
LONG TERM....Lusk
AVIATION...Martin