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Area Forecast Discussion (AFD)

Issued by Peachtree City, GA (FFC)

FXUS62 KFFC 212356

Area Forecast Discussion
National Weather Service Peachtree City GA
756 PM EDT Thu Sep 21 2017

Afternoon/evening convection persists this evening, generally over
the far southern CWA, with a few outlying cells in the metro
Atlanta area. Have updated PoPs/Wx for the next few hours to delay
the removal of precip wording. Still anticipate activity to
diminish/end into the late evening hours. Otherwise, have made
only minimal changes to temperatures and dew points to account for
the latest hourly trends. Current forecast through the next 36
hours looks to be on track.



.PREV DISCUSSION... /Issued 309 PM EDT Thu Sep 21 2017/ 

SHORT TERM /Tonight through Friday Night/...

Very warm and muggy conditions persist across north and central 
Georgia with temps in the 80s to lower 90s. A few storms have popped 
up along the ridges of northeast Georgia but a weak flow aloft is 
limiting development/movement off the higher terrain.

Through Friday night/early Saturday, an upper ridge of high pressure 
will remain firmly entrenched across the mid-MS Valley and lower 
Great Lakes region while a weak upr lvl circulation drifts (extends) 
from eastern North Carolina to the Gulf Coast/panhandle of Florida. 
Diurnally-driven, mainly afternoon and evening, convection will be 
widely scattered (20-30%) at best, with no significant "driver" or 
low lvl forcing nor wind shear to sustain anything long-lasting. 
Temperatures will continue to run 5-10F degrees above normal.


LONG TERM /Saturday through Thursday/...

A broad upper-level ridge will dominate the eastern CONUS over the 
weekend. This ridge will draw moisture from the Atlantic Ocean over 
the region to begin the extended period. Impulses within the upper 
level flow will provide a focus for diurnally driven showers and 
thunderstorms on Saturday afternoon. As such, PoPs in central and 
northern GA could be as high as 30 percent. Not confident in 
increasing PoPs beyond that due to a lack of surface-based forcing. 
High relative humidity values coupled with light winds could lead to 
areas of patchy fog in the early morning hours during the weekend. 
The upper ridge will break down early next week and then re-develop 
in the middle of the week.

GFS/ECMWF/NAM/Canadian models all continue to keep Hurricane Maria 
well to the east of our region. No direct impact from Maria is 
expected to occur in the extended forecast period and Maria will 
instead pass through the South Atlantic Ocean beginning on Sunday. 
Proximity of Maria off the east coast will maintain a general 
northeasterly flow over the region which will keep temperatures 
moderated and set up a zone of subsidence over the southeastern 
CONUS, which will promote drier and more stable conditions. PoPs are 
expected to decrease to minimal values beginning on Sunday and into 
next week. Warm and generally dry conditions are also to be expected 
throughout the remainder of the extended period.



00Z Update...
VFR cigs expected through the period, with the potential for
patchy IFR/MVFR visibilities for the 09-14z period. Isolated to
scattered showers and thunderstorms will develop after 16z and
impact the area through 00-02z, so have mentioned VCSH at all
sites. Light winds overnight will generally stay east through the
day Friday.

//ATL Confidence...00Z Update...
High on all elements.



Athens          66  86  66  85 /  20  20  10  10 
Atlanta         70  85  69  85 /  30  20  10  10 
Blairsville     58  82  60  82 /  20  30  20  20 
Cartersville    66  87  66  86 /  20  20  10  10 
Columbus        73  89  69  87 /  20  30  10  20 
Gainesville     69  84  66  84 /  20  20  10  10 
Macon           68  87  67  86 /  20  30  20  20 
Rome            67  87  66  87 /  20  20  10  10 
Peachtree City  65  86  66  85 /  30  20  10  20 
Vidalia         70  88  69  86 /  50  20  20  20