Area Forecast Discussion
Issued by NWS Atlanta, GA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KFFC 192332
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
732 PM EDT Tue Sep 19 2017



.PREV DISCUSSION... /Issued 315 PM EDT Tue Sep 19 2017/

SHORT TERM /Tonight through Wednesday Night/...
Convection to the west has been more plentiful in coverage than
earlier models might have projected but mesoanalysis indicates
plenty of reasons why. Mixed layer CAPE values over portions of
Alabama are in excess of 2000 J/KG and sfc based over 3000 J/KG.
With precipitable water over 1.50 inches, this along with the
robust energy has been more than enough to warrant the enhanced
coverage to our west.

The big question remains how much of this activity holds together
for the local area. Although no where near that much energy
resides currently over the western zones, RAP does bring some 1500
CAPE values in late this afternoon. Have therefore continued with
the high end chance pops through this evening for NW corner but
stopped short of likely based on HRRR models quick dissipation.

Shortwave is a slow mover but should move across the northern
sections during the overnight period with limited pop coverage.
This would setup the Central zones as having the best chance for
pops on Wed. Models show moisture pooling from CSG to MCN and
points southward with PWs near 1.75 inches along with modest CAPE
values of 1500 J/KG. Still some residual cool air aloft so cannot
rule out some isolated strong storms during the afternoon hours.

Deese

LONG TERM /Thursday through Tuesday/...
Only slight changes have been made to the extended forecast. The
ridge pattern positioned over the area is expected to have broken
down by the beginning of the extended period and will be replaced by
weak upper-level troughing. This trough pattern will contain
multiple shortwaves embedded within. As a result of these upper-
level impulses, isolated to scattered diurnally favored showers and
thunderstorms can be expected in the area in the later parts of the
week and into the weekend. The highest PoPs will be on Thursday
and Friday afternoon, mainly in the 30 to 40 percent range. PoPs
have been lowered on Friday from the previous forecast due to a
lowered confidence in surface-based forcing.

GFS/ECMWF/NAM/Canadian models all continue to keep any direct impact
from Jose/Maria far to the east of the area. The official forecast
from NHC reflects this as well. Maria is expected to force a drier
and more stable air mass into the area on Sunday which will remain
in place until Tuesday. This air mass will lead to more seasonal
temperatures and humidity, along with lower PoPs, starting during
the weekend and into the early parts of next week.

09/NListemaa

&&

.AVIATION...
00Z Update...
VFR expected through the period. Rain and a few embedded
thunderstorms moving east toward the GA/AL border continue to
dissipate into the state. At this time, have opted for VCSH at
KCSG, but no precip mentioned elsewhere tonight. For tomorrow,
isolated to scattered showers are expected generally after 18z,
and have gone with VCSH for all TAF sites. W-NW winds will be
light overnight, then increase to 4-6kt through the day. Slight
visibility reductions to MVFR are possible for KCSG and KMCN
overnight.

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

31

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          67  88  66  88 /  20  20  10  30
Atlanta         70  87  70  87 /  20  20  10  30
Blairsville     61  82  60  83 /  20  20  10  40
Cartersville    66  87  65  88 /  20  20  10  30
Columbus        71  90  71  90 /  20  20  20  40
Gainesville     68  86  67  85 /  20  20  10  30
Macon           68  90  69  89 /  10  20  20  40
Rome            66  88  66  88 /  30  20  10  30
Peachtree City  67  88  67  87 /  20  20  10  30
Vidalia         71  91  71  89 /  20  30  30  50

&&

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

$$

SHORT TERM...31
LONG TERM....41
AVIATION...31



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.