755
FXUS62 KFFC 251850
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
250 PM EDT Wed Sep 25 2024

...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This afternoon through Thursday)
Issued at 249 PM EDT Wed Sep 25 2024

Highlights:

-Periods of heavy rainfall and potential for flooding through the
remainder of today in association with a frontal system

-Growing concern for intense widespread heavy rainfall leading to
flash flooding, and increasing threat for tropical storm force winds
on Thursday as a result of Tropical Storm Helene

-A Flood Watch remains in effect through Friday. Tropical headlines
remain and/or now in effect for much of Central Georgia through
Friday.

Showers and storms are ramping up across the state this afternoon
with latest radar showing the axis of heaviest rainfall currently
situated along the I-85 corridor. This activity is slow moving and
thus flooding potential is increased. Additionally, a few strong to
severe thunderstorms have been noted with an isolated tornado threat
through the evening. SPC maintains a Marginal Risk (Level 1 out of
5) this afternoon. A High Risk (Level 4 out of 4) for excessive
rainfall exists for much of Northeast GA today. The presence of
clouds and rain has kept temperatures lower compared to the past few
days with current readings largely in the 70s (80s in the southeast
where there are less clouds and slightly lower PoPs).

The main features in play over the next few days will be 500mb low
and associated trough currently situated across the Mid-MS Valley
Region and the low associated with Hurricane Helene now to the
northeast of the Yucatan Peninsula. At the sfc, a frontal boundary
will continue to sag into the forecast area and Hurricane Helene is
expected to quickly track northward and is forecast to make landfall
as a major hurricane on Thursday evening. This is quite a unique set
up as the tropical system will interact and become enveloped within
the upper level system thats to our northwest.

As plentiful tropical moisture continues to overspread into the
region increasing clouds and rain/thunder chances will continue
through the remainder of the day. Aligning with a sfc convergence
zone oriented SW to NE in north-central GA, looks like the axis of
heaviest rainfall through today will be along and in the vicinity of
the I-85 corridor. Forecast rainfall totals for today are currently
1-3 inches with locally higher amounts. Additionally, isolated
strong to severe thunderstorms will continue to be a possibility
through the evening. What is occurring today is a predecessor rain
event prior to the tropical event that will continue to unfold on
Thursday.

A note prior to any details concerning Hurricane Helene... please DO
NOT focus on the exact track of this system. Impacts and hazards
extend well beyond the main track. The time is NOW to make
preparations as this is a quickly evolving system.

Hurricane Helene is expected to quickly track northward and
strengthen to major hurricane status prior to making landfall on
Thursday evening. This is a largely quick moving system and
widespread impacts are expected across North and Central Georgia
Thursday into Friday. A Hurricane Warning is now in effect for
extreme south-central GA (Harris County up to Schley and Macon,
eastward to Pulaski and Wilcox counties), a Tropical Storm Warning
in effect for Harris County as far east as Bibb County and then all
counties southward to the Hurricane Warning. A Tropical Storm Watch
encompasses the remainder of  North and Central GA (including metro
ATL). As this system continues to evolve potential upgrades may be
warranted. A breakdown of the hazards is listed below:

*Intense Heavy Rainfall and Flash Flooding:

A Flood Watch remains in effect for all of North and Central GA
through Friday afternoon. Depending on how this situation evolves
over the next 48 hours this may need to be extended in time. With
heavy rainfall already occurring today saturating the soils, there
is a growing concern for the flash flooding risk and potentially
historic rainfall on Thursday as a result of this tropical system.
Forecast rainfall totals for Thursday ranging 3 to 6 inches with
locally higher amounts. Forecast Storm Total Rainfall Today through
Friday evening ranging 4 to 10 inches with amounts over 12 inches
possible. WPC maintains a Moderate Risk (Level 3 out of 4) for
Excessive Rainfall for the majority of North and Central GA with a
High Risk (Level 4 out of 4) for Excessive Rainfall encompassing the
Southern Appalachians (northeast GA). Needless to say the threat
for potential life threatening flash flooding is increasing.

*Tropical Storm Force Winds:

With this latest forecast update, the potential for areas
experiencing tropical storm force (and even hurricane force) winds
has increased. Areas currently in the Hurricane Warning could see
hurricane and tropical storm force winds potentially exceeding 70
MPH. This coupled with intense heavy rainfall and saturated soils,
will likely lead to widespread and extended power outages as a
result of downed powerlines and trees.

*Short-lived, brief tornadoes:

Tornado development in association with tropical system typically
favor the northeast quadrant of the storm relative to its motion
within the outer rainbands. Thus, based on Hurricane Helene`s
current trend a good portion of southeast and east-central GA are in
the more `ideal` location where quick, short-lived tornadoes could
develop in the rainbands. The Storm Prediction Center maintains a
Slight (Level 2 out of 5) to Marginal Risk (Level 1 out of 5) in the
areas previously mentioned.

07

&&

.LONG TERM...
(Friday morning through next Tuesday)
Issued at 249 PM EDT Wed Sep 25 2024

out of Georgia by late Friday morning and absorb into the broader
trough extending over the Southeast. After copious amounts of
rainfall through Friday morning, considerably drier conditions are
favored through the long term. The remnant low will extend from the
Ohio Valley southward through the weekend. The focus for most
additional rainfall will thus be to our north, but isolated to
widely scattered PoPs will linger mainly across far north Georgia
through early next week. A larger scale trough should push a cold
front into the area mid next week with a renewed push of drier
air.

RW

&&

.AVIATION...
(18Z TAFS)
Issued at 145 PM EDT Wed Sep 25 2024

A messy aviation forecast is expected to continue over the next
several days. Axis of shra/tsra spreading over much of the area
(including all sites right now except MCN/AHN) this aftn. This is
expected to continue in waves with deteriorating cigs expected
through the period. Winds expected to be on the east side though
winds may be erratic, gusty and VRB with any outflows. Winds
briefly shift more to the east btwn 06-12z. IFR cigs expected as
early as 05-06z continuing through much of the period. Gusty ESE
winds as early as 12z Thursday.

//ATL Confidence...18Z Update...

Medium confidence on all elements.

07

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          67  74  67  77 / 100 100 100  40
Atlanta         67  73  66  75 / 100 100 100  40
Blairsville     61  69  62  71 / 100 100 100  90
Cartersville    64  74  65  75 /  90 100 100  60
Columbus        69  76  67  78 / 100 100 100  30
Gainesville     65  72  67  74 / 100 100 100  60
Macon           69  77  68  79 / 100 100 100  20
Rome            64  75  66  76 /  90 100 100  80
Peachtree City  66  73  65  75 / 100 100 100  30
Vidalia         72  81  73  84 /  90 100 100  10

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday afternoon for GAZ001>009-011>016-
019>025-027-030>039-041>062-066>076-078>086-089>098-102>113.

Tropical Storm Watch for GAZ001>009-011>016-019>025-027-030>039-
041>062-066>076-084>086.

Tropical Storm Warning for GAZ078>083-089>091-094>098-109>113.

Hurricane Warning for GAZ092-093-102>108.

&&

$$

SHORT TERM...07
LONG TERM....RW
AVIATION...07