376
FXUS62 KFFC 231832
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
232 PM EDT Mon Sep 23 2024



...New 18Z Aviation Discussion...

.SHORT TERM...
(Today through Tuesday)
Issued at 332 AM EDT Mon Sep 23 2024

500mb analysis shows NW flow aloft with a high pressure anchored
off the SE coast of TX. This high center should migrate eastward
across the northern GOMEX through the period. The mid level flow
across the state should go briefly zonal and then SW by early
Tuesday as a longwave trough pushes into the Mid Mississippi River
valley.

At the surface, a weak surface trough continues across central
portions of the state. A weak frontal boundary will approach from
the west through the period while ridging remains across the
northern GOMEX. Moisture will continue to slowly increase across
the area, along with the chances for pops, especially across the
northern tier of zones. The southern tier of zones will be closest
to the mid level and surface ridges and pops remain lowest in
this region. Pops will remain isold/sct in nature across the
northern half of the CWA through the period. Severe weather is not
anticipated at this time.

Temps continue above normal through the period. Adjusted the MaxT
values upwards a couple of degrees from the blend. ATL may
approach another record high for the next two days.

NListemaa

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 332 AM EDT Mon Sep 23 2024

At the upper levels, a positively-tilted trough will be
positioned over the eastern CONUS at the start of the long-term
period. At the surface, a weak area of low pressure over the Ohio
River Valley and eastern Great Lakes region will push a weak cold
front across the Tennessee River Valley, perhaps making it into
north Georgia. As a result, rain chances will be greatest
generally along and north of the I-85 corridor Tuesday night
through Wednesday night. Both instability (CAPE and mid-level
lapse rates) and wind shear from the surface to 500 mb will be
marginal at best, indicating that while isolated to scattered
thunderstorms are expected, widespread severe weather is unlikely.

The impactful portion of the long-term period will be Thursday
through Saturday. The National Hurricane Center (NHC) is
indicating a high (70%) chance for tropical development over the
northwestern Caribbean Sea and adjacent portions of Central
America in the next 48 hours. Ultimately, a tropical depression or
tropical storm is very likely (90% chance) to develop in the next
few days as the system moves northward into the southeastern Gulf
of Mexico. During the latter half of the week, the system is
expected to track generally northward across the eastern Gulf.

At 4-5 days out, it is still best to lean on ensemble guidance to
get an idea of the potential evolution of the system and
potential impacts on the Southeast. The GEFS moves the system
northward slightly faster than does the EPS, but the tracks that
both ensembles depict are very similar, with the system having a
spatial extent from Florida to Louisiana. The track of this system
will depend largely on how the aforementioned upper-level trough
evolves over the eastern CONUS (its strength, position, southern
extent) and thus how it steers the system.

The degree of impacts across north and central Georgia is still
relatively uncertain, but we are currently expecting most impacts
to occur on Thursday and Friday. As far as impacts, periods of
heavy rainfall and resulting flash flooding and/or river flooding,
gusty winds, and tornadoes will be on the table should north and
central Georgia be on the eastern side of the system. Forecast
rainfall totals are largely unchanged from the previous forecast
package, with essentially area-wide totals of 3" to 4". Localized
swaths of 5" or more are possible in the event of intense and/or
long-lived rainbands, but it is futile to attempt to pin down
where such rainfall maxima could occur at 4-5 days out.

Residual tropical moisture, along with what ensemble guidance
suggests is expansive upper-level troughing, looks to keep 20% to
30% PoPs in the forecast on Saturday and Sunday. Aside from
Wednesday, highs will be in the 70s and 80s thanks to increasing
cloud cover and increasing coverage of showers and storms.

Martin

&&

.AVIATION...
(18Z TAFS)
Issued at 224 PM EDT Mon Sep 23 2024

VFR through TAF period. Expecting some afternoon cu impacts at
most all sites today and tomorrow. Winds will be on the west side
through period in the metro at 5-10 kts, going light overnight. In
MCN/CSG, winds will be more southerly tomorrow, similar speeds.
Some TSRA impacts possible at AHN until 00Z, starting around 20Z.

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

High all elements.

Lusk

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          69  91  68  83 /  20  20  30  40
Atlanta         72  93  71  82 /  10  10  30  60
Blairsville     64  84  63  74 /  20  40  60  80
Cartersville    69  93  67  81 /  10  20  40  80
Columbus        73  93  72  85 /   0   0  20  60
Gainesville     69  90  68  79 /  20  20  40  60
Macon           72  93  70  87 /  10  10   0  30
Rome            69  93  67  80 /  10  20  60  90
Peachtree City  70  91  68  82 /   0  10  20  60
Vidalia         72  93  70  89 /  10   0   0  10

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...NListemaa
LONG TERM....Martin
AVIATION...Lusk