086 
FXUS62 KFFC 211142 AAA
AFDFFC

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
742 AM EDT Sat Aug 21 2021



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


&&

.PREV DISCUSSION... /Issued 414 AM EDT Sat Aug 21 2021/ 

SHORT TERM /Today through Sunday/...
Similar to yesterday, the CWA is situated between an upper trough
over the Mid-Atlantic States and an upper ridge centered over TX 
and LA. The GFS and NAM are progging a couple weak 500-mb 
disturbances to dive southeastward within the NW flow today, which
should act as a focus for convection and thus higher PoPs mainly 
across the western half or so of the CWA. Still, the entire CWA 
will see the possibility for scattered showers and thunderstorms 
this afternoon and evening as daytime heating and PWATs of 1.8" to
2.2" help generate SBCAPE values around 1000-2000 J/kg. A few 
strong storms cannot be ruled out with the main threats being 
locally heavy rainfall and gusty winds. Progressive storm motion 
should preclude any isolated flash flooding concerns.

A similar synoptic setup is on tap for Sunday, although the upper
ridge will amplify a bit across the central U.S. and flatten the 
upper trough, pushing it further up the Eastern Seaboard. 
Scattered showers and thunderstorms are expected once again 
tomorrow afternoon and evening across north and central Georgia, 
and a few storms could be strong with locally heavy rainfall and 
gusty winds.

Martin


LONG TERM /Sunday Night through Friday/...
Upper flow pattern begins to shift to the north Sunday evening 
into Monday as the FA finds itself sandwiched between an upper 
high to the west and an upper low to the NE. By Monday afternoon 
the aforementioned upper level low will begin to pull northward 
allowing the upper high to expand across the southeastern CONUS. 
In response to this expansion suppression combined with drier air 
being advected into the mid and upper levels will result in 
decreased PoP coverage area wide Tuesday. The effects of the upper
high will be short lived as it retrogrades westward Wednesday and
a Bermuda High sets up to the east. 

With the CWA now sandwiched between two upper level highs deep 
layer moisture will be allowed to return to the region thanks in 
part to a strong return flow off the Atlantic. This pattern will 
favor increase PoPs each day starting Wednesday through the end of
the week. Further enhancing moistures levels will be a weak open 
tropical wave that will nose into the area from the Florida Big 
Bend Thursday. All of that being said, one can expect a hot and 
humid weather pattern with usual summer time diurnal convection 
mid week and on. 

28

&&


.AVIATION...
12Z Update...
IFR and LIFR cigs have overspread much of north GA this morning. 
Have BKN007 at ATL until 14z, after which cigs should lift to low-
MVFR. Upper-MVFR to VFR cigs (around 030-040) are expected 
through the afternoon. An upper-level disturbance will track 
southeastward over western GA in the afternoon, so have enough 
confidence to do a TEMPO at KATL for TSRA from 18z to 22z. Winds 
will be west around 5-10 kts, aside from any brief, gusty t-storm 
winds. With ample low-level moisture remaining in place, cigs 
should drop late tonight into Sunday morning, likely to IFR to 
LIFR again.

//ATL Confidence...12Z Update...
Medium confidence on timing of cigs lifting, and on afternoon
convection. High confidence on all other elements.

Martin

&&


.PRELIMINARY POINT TEMPS/POPS...
Athens          88  71  90  71 /  30  20  30  10 
Atlanta         86  71  89  72 /  50  30  30  10 
Blairsville     83  65  86  64 /  30  20  30  20 
Cartersville    85  70  90  71 /  60  30  30  10 
Columbus        88  72  90  73 /  60  40  50  30 
Gainesville     87  70  89  71 /  30  20  30  20 
Macon           89  72  90  72 /  60  30  50  30 
Rome            86  71  91  71 /  70  30  30  10 
Peachtree City  86  70  89  71 /  50  30  40  20 
Vidalia         90  74  89  74 /  40  30  60  40 

&&

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

$$

SHORT TERM...Martin
LONG TERM....28
AVIATION...Martin