180
FXUS62 KFFC 121900
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
300 PM EDT Thu Sep 12 2024


...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This afternoon through Friday)
Issued at 259 PM EDT Thu Sep 12 2024

Highlights:

- Cooler, cloudy and breezy conditions continue through Friday. A
Wind Advisory remains in effect through early Friday morning.

- On and off light to moderate rainfall is slated to continue
through Friday. A Flood Watch remains in effect through Friday
evening with far NW Georgia now included.

The first big push of rainfall is now entering eastern GA at the
time of this writing. GOES LL Water Vapor imagery shows drier air
entering into Central AL and portions of western GA. CAMs are lining
up fairly well with latest trends and a drier period looks to
persist through most of the evening. A CAD wedge remains solidly in
place and is being reinforced by the influx of moisture. Thus,
cloudy conditions and cooler temperatures will persist through the
evening. Additionally, winds across the western half of the forecast
area have begun to pick up as a result of a tightening pressure
gradient (btwn the tropical system and CAD wedge). Not anticipating
much in the way of thunder today. The warm front still remains to
the south of the area and will struggle to lift northward into the
area with the CAD wedge in place. So with this forecast package,
largely kept thunder out of the forecast. With winds picking up this
afternoon, no changes were made to the Wind Advisory. Wind gusts up
to 35 MPH with isolated gusts nearing 40 MPH in the northeast can be
expected through early Friday. Gusts may linger through the day
Friday but are not expected to be the magnitude of what they are
presently. The far northwest portion of the forecast area has been
added to the Flood Watch and that remains in effect through Friday
evening. Highest forecast rainfall totals are still confined to far
western GA with totals of 2 to 3 inches and isolated totals nearing
4 inches will be possible.

Temperatures have struggled to climb above the mid-70s today which
is a notable change compared to the past few weeks. Temperatures
will be similar tomorrow with forecast highs in the upper 60s to
70s. Low clouds and patchy fog will develop overnight so use caution
if on the roadways.

We can largely expect unsettled weather to continue through the day
Friday and perhaps into the weekend (see long term discussion). A
500mb ridge is situated across the Great Lakes Region extending
southeast towards the coastal Carolinas/far Southeast States. This
may act to slow and even keep the remnant low of Francine around
portions of the MS Valley/Midsouth region through the end of the
week. One more notable change compared to the previous forecasts is
the influence of the present CAD wedge and the impacts that may have
on rainfall amounts the area will receive through Friday and even
into the weekend. So far soils have faired well with the rainfall
that has occurred. Additional forecast rainfall through early
Saturday will range from 1 to 3 inches with isolated 4 inches. These
higher totals look to be confined to west of I-75 initially and
extending further to the northeast going into Saturday. The biggest
concern for flash flooding will be the typical low lying areas,
urban areas, and flood prone areas.

The tornado threat remains very low today and still a possibility
tomorrow. The lack of CAPE, helicities, and lift from the warm front
has limited this threat.

07

&&

.LONG TERM...
(Saturday morning through next Wednesday)
Issued at 259 PM EDT Thu Sep 12 2024

As the long term period begins on Saturday morning, the remnant low
from Francine will have been blocked by mid-level ridging to the
north, and will be slowly drifting southeastward through western
Tennessee. While the system will be continuing to weaken and become
less organized, deep tropical moisture on the eastern side of the
storm will continue to extend across north and central Georgia
through the weekend. This will keep a very moist airmass in place
across the forecast area, which will be characterized by dewpoints
in the upper 60s to low 70s and precipitable water values ranging
from 1.5 to 2 inches. High pressure associated with the broad ridge
to the north will keep a CAD wedge in place along the lee side of
the Appalachians, which will continue to extend into north Georgia.

The airmass will be favorable for heavy rainfall during this
timeframe. Furthermore, there will be broad convergence in the low
level flow, with easterly flow within the wedge and westerly to
southwesterly flow near Francine. It is also likely to see a narrow
band of locally stronger convergence set up in the low level flow on
Saturday, although it remains to be seen where this will occur. As
such, model guidance continues to show a fairly wide spread of QPF
solutions, though it overall favors the potential for corridors of
heavy/training bands of rainfall through early Sunday within the
broad, persistent low level convergence. Additional rainfall amounts
between 1-2 inches are forecast across the majority of the area on
Saturday-Sunday, although some locations could see as much as 3
inches depending on where heavy/training bands occur. Given these
additional rainfall amounts combined with wet soils from
today/Friday, it will be possible to see localized flash flooding
and river flooding concerns associated with the heaviest rain. The
WPC has thus maintained a Slight Risk (level 2 of 4) for Excessive
Rainfall for Saturday and a Marginal Risk (level 1 of 4) on Sunday.

North and central Georgia remain in the soupy airmass in the early
parts of next week. A broad, weak upper trough from Francine`s
remnants will linger over the Southeast. Scattered showers and
thunderstorms will remain on Monday and Tuesday, which will be
diurnally enhanced during the afternoon hours each day. Mostly
cloudy to overcast skies and the cool dome underneath the wedge will
keep temperatures below average through the weekend. This is
especially true over north Georgia, where highs will be limited to
the mid 70s (compared to upper 70s to low 80s in central Georgia).
With breaking cloud cover, temperatures will return to near daily
normals by Tuesday and Wednesday with highs in the low to mid 80s.
With a stationary front lingering over the Carolina Coastline and
over the Atlantic, the potential remains for the organization of a
new low pressure system along the front. However, location and
degree of strengthening remain highly uncertain. Depending on how
this evolves, the potential for any additional enhanced moisture
encroaching on the local area next week will need to be monitored
given the current expectations of heavy rainfall through the
weekend.

King

&&

.AVIATION...
(18Z TAFS)
Issued at 149 PM EDT Thu Sep 12 2024

Latest radar shows the first wave of rain associated with Francine
moving through eastern GA, thus impacting AHN for a few more
hours. The remainder of the sites may catch a brief break in the
rain for a few hours before another rainband lifts through later
this evening. Cigs will gradually deteriorate through the period
with widespread IFR cigs btwn 08-12z and potentially before this.
Winds largely to remain elevated through the period though gusts
may taper slightly overnight.

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

Medium confidence on all elements.

07

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          65  77  67  74 /  50  70  80  80
Atlanta         67  76  67  76 /  50  70  80  80
Blairsville     60  72  62  70 /  50  70  80  80
Cartersville    65  78  67  76 /  50  70  80  80
Columbus        69  82  69  82 /  60  80  80  60
Gainesville     64  75  67  72 /  50  70  80  70
Macon           69  82  68  80 /  40  80  80  70
Rome            66  80  67  77 /  50  70  80  80
Peachtree City  66  77  67  77 /  50  70  80  80
Vidalia         71  85  71  83 /  30  60  60  60

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday evening for GAZ001-002-011-019-030-
041-042-052-053-066>069-078>080-089>092-102>104.

Wind Advisory until 5 AM EDT Friday for GAZ001>009-011>013-
019>021-030>033-043>045.

&&

$$

SHORT TERM...07
LONG TERM....King
AVIATION...07