702
FXUS62 KFFC 030016
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
816 PM EDT Tue Jul 2 2024



...New 00Z Aviation Discussion...

.UPDATE...
Issued at 758 PM EDT Tue Jul 2 2024

Minor updates to PoPs and Tds to account for some model trends.
Drier air may hang on a bit longer up in north Georgia tomorrow as
our mid-Atlantic airmass sticks around, though breakdown is still
expected to occur with strong afternoon mixing.

Lusk

&&

.SHORT TERM...
(This afternoon through Wednesday)
Issued at 252 PM EDT Tue Jul 2 2024

Upper level high pressure remains centered over Mississippi/Alabama,
which is expected to continue expanding eastward into an E-W
oriented ridge over the short term period. An associated surface
high pressure is positioned near the New England coast. Surface
ridging associated with the high has developed along the lee side
of the Appalachians and has spread across much of north Georgia
from the northeast. The airmass under this wedge of high pressure
is noticeably milder and drier than observed the last several
days. High temperatures will range from the mid 80s to near 90
this afternoon. Dewpoints have also dropped into the 50s to low
60s in the Atlanta metro area and to the north and east. The
frontal boundary that traversed through the forecast area
yesterday has become stationary across south Georgia, with
scattered showers and thunderstorms ongoing in the vicinity of the
front. Some of this precipitation will continue across portions
of south-central Georgia through the afternoon, but a stable
airmass within the wedge will keep PoPs to a minimum across the
northern 2/3 of the forecast area.

After a cloudy start the morning across the majority of the forecast
area on Wednesday, the wedge will begin to break down as the high
pressure center moves offshore into the Atlantic. At this time, the
frontal boundary will slowly lift back to the northeast, with
dewpoints in the upper 60s and 70s creeping back to the north in
kind. With increasing dewpoints and highs rising into the low 90s
across the majority of north and central Georgia (with the exception
of the higher elevations of the far northeast), MUCAPE values are
forecast to increase to 1000-1500 J/kg in portions of central and
west Georgia, south and west of the frontal boundary. These
instability values will be sufficient for scattered diurnally-driven
thunderstorms, with the highest coverage in south-central Georgia
where there will be the greatest low level moisture and
precipitable water values approaching 2 inches. With vertical
profiles indicating tall but thin CAPE profiles and very limited
shear, the threat for severe weather on Wednesday is shaping up to
be quite low.

King

&&

.LONG TERM...
(Thursday morning through next Monday)
Issued at 252 PM EDT Tue Jul 2 2024

Key Messages:

 - A Heat Advisory may be needed (40% chance) for portions of east
central Georgia between Friday and Sunday.

 - Afternoon and evening thunderstorms should become more numerous
Friday, Saturday and Sunday.

Heat Concerns to End the Week:

The core of an upper level ridge will drift gradually eastward over
the course of this week. Overall, 500 mb heights should peak in
Georgia on Thursday or Friday, but 850 mb temperatures may continue
to inch upwards over the weekend. These trends should allow
temperatures to climb back towards the mid and upper 90s to conclude
the week. The warmer temperatures should be accompanied by surface
dewpoints in the 69-74 degree range, and this may push afternoon
heat indices back into the triple digits. Our current forecast
suggests heat indices above 105 in parts of Georgia Thursday,
Friday, Saturday and Sunday. If these values hold (a 1-2 degree
decrease in surface dewpoints or temperatures would prevent values
over 105) then a Heat Advisory (40% chance) may be warranted for
some locations south and east of Atlanta. Peak heat indices in the
Atlanta Metro are currently forecast to be in the 100 to 104 degree
range.

Thunderstorms Chances Trending Upwards:

An upper level trough tracking through the Great Lakes should push a
weak frontal boundary towards Georgia late in the week. While the
strength of this boundary may be fading, it should still provide
sufficient lift to serve as a focal point for storm activity.
Guidance from the EPS and GEFS suggests increasing instability (Mean
SBCAPE values > 1000 j/kg) and moisture (PW values near 2 inches)
along and ahead of the frontal boundary. Combine these factors with
diurnal heating and the lift/surface convergence along the frontal
boundary, and an uptick in the coverage of afternoon and evening
thunderstorms is anticipated. Our forecast rain chances currently
peak near 60% on Saturday. The potential for strong or severe
thunderstorms remains low due to limited shear (surface to 500 mb
bulk shear generally less than 15 kt) and modest mid level lapse
rates (700-500 mb values near 5.5 C/km). If stronger storms do
occur, they would be most probable near the GA/TN border where bulk
shear values my be closer to 20 kt Friday and Saturday. Rainfall
rates may be local heavy with any storms that occur (1-2 inches per
hour) due to the potential for climatologically high PW values (in
the 90th percentile).

Albright

&&

.AVIATION...
(00Z TAFS)
Issued at 758 PM EDT Tue Jul 2 2024

VFR to start TAF period. Cigs that briefly approached ATL from
south have backed away for now. By 09-10Z, cigs expected to
redevelop and surge northward towards metro sites, with impacts at
MCN and CSG even earlier. This deck is expected to bring MVFR
impacts to metro and IFR to MCN and CSG, though IFR cigs may be
possible for periods at some metro TAF sites, including ATL. These
should begin to SCT after sunrise by 16Z. Some afternoon SHRA/TSRA
possible at MCN/CSG. Not confident enough in coverage to introduce
at metro TAF sites yet. Winds will be E to SE, 5-10 kts.

//ATL Confidence...00Z Update...
Medium confidence morning cigs, high all others.

Lusk

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          69  92  73  95 /  10  20  10  30
Atlanta         73  91  75  94 /  10  30  20  40
Blairsville     65  86  68  89 /  10  20  10  60
Cartersville    72  93  74  95 /  10  20  10  40
Columbus        76  93  75  94 /  10  40  30  50
Gainesville     70  90  74  94 /  10  20  10  40
Macon           73  93  73  95 /  10  40  30  30
Rome            73  94  75  96 /   0  20  10  50
Peachtree City  72  91  73  94 /  10  30  20  40
Vidalia         74  91  75  94 /  20  50  30  30

&&

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

$$

SHORT TERM...King
LONG TERM....Albright
AVIATION...Lusk