220 
FXUS62 KFFC 201136
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
736 AM EDT Mon Sep 20 2021

...Updated for 12z Aviation Discussion...

.PREV DISCUSSION... /Issued 456 AM EDT Mon Sep 20 2021/ 

SHORT TERM /Today through Tuesday/...

Another rinse and repeat forecast, quite literally, wet weather is 
ahead through the short term one again. Scattered showers will 
continue continue to lift northward across the area this afternoon 
as the CWA remains downstream of the mid/upper low over the Arklatex 
region. PWAT values remain well above climatological avg, around or 
above 2". Current forecast additional rainfall amounts through 
tomorrow range from 1-2" totals across much of the northern sector 
of the CWA, with locally higher amounts across the NE GA mtns. 

Heavy rainfall remains the primary concern, especially for areas 
highlighted in the ongoing Flash Flood Watch where the pockets of 
heaviest rainfall totals have so far been concentrated.
Only major changes to the current Flash Watch is the removal of 
portions in the SW CWA, and extending the watch through 00z this 
evening. Can't rule out the extension of the current FFA towards the 
NE GA corner later today, but given low QPE from yesterday across 
that area, confidence is too low to pull the trigger for issuance at 
this time.

Morgan

LONG TERM /Tuesday Night through Sunday/...

An upper level trough continues to march eastward across central 
CONUS and will dig southeastward into the ArkLaTex region at the 
beginning of the long term forecast period. The tropical airmass 
that has been lingering for the past several days has become 
sufficiently saturated from persistent upper level southwesterly 
flow from the Gulf of Mexico. As a result, elevated PoPs for Tuesday 
overnight remain in the forecast with a chance of thunderstorms 
possible, especially associated with any small upper level 
disturbances ahead of the surface frontal passage. 

GFS and Euro show good agreement on timing of the surface front 
impacting the northwest sector of our CWA by Wednesday. As the front 
progresses southeastward overnight Wednesday, the upper level trough 
transitions into a cut off low and ejects northeastward into the 
Great Lakes region. At the moment, the dynamic setup ahead of the 
front does not lend itself to widespread severe weather. However, 
low level shear and moderate instability Wednesday afternoon will 
allow for a chance of isolated strong storms where damaging wind 
gusts and heavy rainfall are the main threats. Highest QPF is 
expected to be in areas of elevated terrain in North Georgia, but 
with PWAT values ranging from 1.75 to 2.25 inches, periods of 
locally heavy rainfall will be possible across the entire CWA. 
Enhanced cloud cover from the beginning of the period through 
Wednesday overnight will limit diurnal temperature, where lows drop 
into the 60s to 70s and highs in the 70s to 80s.

Once the front passes through early Thursday, high pressure begins 
to build in across the CWA. Flannel fans will rejoice as cooler than 
average temperatures and dry conditions dominate the weather pattern 
throughout the rest of the forecast period. High temperatures in the 
upper 60s to low 80s will be expected with low temperatures in the 
50s to low 60s. Some mountainous areas will drop into the upper 40s 
for low temperatures.

KAL

&&

.AVIATION...
12Z Update...

Widespread IFR/MVFR cigs this morning with SHRA/RA across the 
metro TAF sites this morning. Expecting this trend to continue
through with not much improvement during the day, staying BKN/OVC
with IFR/lower end MVFR cigs through the afternoon thanks to 
persistent RA/SHRA. Cigs should lower once again to IFR moving 
into tomorrow night. Winds remain from the east with speeds 
increasing to 8-12kts today, with some gusts up to 15-17kts 
possible during the late afternoon.


//ATL Confidence...12Z Update...

Medium confidence on all elements.

Morgan

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          75  69  79  68 /  80  60  70  60 
Atlanta         75  70  80  68 /  80  50  60  60 
Blairsville     71  65  75  63 /  70  60  70  70 
Cartersville    76  69  81  67 /  80  50  60  60 
Columbus        80  71  84  70 /  70  50  60  40 
Gainesville     73  68  77  67 /  80  60  70  60 
Macon           79  71  84  70 /  70  40  70  40 
Rome            76  70  82  68 /  80  50  60  60 
Peachtree City  77  70  82  67 /  80  50  60  50 
Vidalia         80  72  84  72 /  70  50  80  40 

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through this evening for the following zones: 
Bartow...Carroll...Catoosa...Chattooga...Cherokee...Cobb...
Coweta...Dade...Douglas...Fayette...Floyd...Gilmer...Gordon...
Haralson...Heard...Meriwether...Murray...North Fulton...
Paulding...Pickens...Polk...South Fulton...Troup...Walker...
Whitfield.

&&

$$

SHORT TERM...Morgan
LONG TERM....KAL
AVIATION...Morgan