855
FXUS62 KFFC 291123
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
723 AM EDT Sat Jun 29 2024



...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Sunday)
Issued at 403 AM EDT Sat Jun 29 2024

At a glance:

  - Afternoon showers and thunderstorms each day.
  - Increasing heat indices through the weekend.

The weak upper level trough across Central GA has become diffuse, and
a rather narrow E/W upper ridge will build in its place through the
weekend. Shower and thunderstorm activity is expected to remain
scattered and diurnally driven through the short term. Precipitable
water values are forecast to remain very high through the period was
well, with values between 2 and 2.25". The dry layer aloft centered
around 450-500 millibars with gradually moisten through the weekend.

Late yesterday evening, showers and isolated thunderstorms spread
north from the Thomaston area into the Atlanta metro area. This
activity has been on a very gradual weakening trend through the
night, with the last lightning detected before midnight. CAPE values
across the area have continued to decrease, although there has been a
slight uptick over the past hour or two from the S Atlanta metro area
to Columbus and Macon.

Shower and thunderstorm activity is expected to develop this afternoon
across the area, with the best chances across the NW third of the
County Warning Area (CWA). Have adjusted PoPs down a bit from the NBM
consensus due to the expected strengthening of the upper ridge and
the lingering dry layer aloft. For Sunday, have gone with 50 to 60
percent PoPs across the area with slightly lower PoPs across the
central portion of the CWA (directly beneath the upper ridge). Due to
the fairly slow storm motion and high precipitable water, locally
heavy rainfall is possible in the heaviest showers and storms. Once
again, storms are expected to remain below severe limits, although
precipitation loading may produce strong wind gusts in the heaviest
storms.

High temperatures this afternoon should range from near 80 in the
highest terrain of the NE mountains to the mid 90s across the SE
half of the area. After adjusting afternoon dew points to account for
mixing, heat indices E of Macon should top out around 103 today. Low
temperatures tonight will range from the mid 60s on the highest
ridges of the NE to the lower to mid 70s elsewhere. With hotter
ambient temperatures on Sunday (mid 80s in the NE mountains to mid
90s elsewhere) and slightly higher surface dew points, heat indices
may reach 105 to 107 From Athens to Macon and points E. If this trend
continues, a Heat Advisory may be needed in that area. /SEC

&&

.LONG TERM...
(Sunday night through Friday)
Issued at 403 AM EDT Sat Jun 29 2024

Beginning the long term period with Monday, the dampened 500 mb
ridge axis continues over much of the south with Georgia on the
eastern periphery. Meanwhile to the north of the ridge, several
troughing features attempt to deepen as they move east every couple
of days through the pattern. With us being in a northwesterly flow
due to this, there is just enough vorticity that makes it to Georgia
to cause daily rain chances through Wednesday into Thursday. Models
are also forecasting PWATs at 2+ inches through the end of next week
which are above the 90th percentile for this time of year (1.80-
1.90"). This in combination with the pushes of vorticity into the
area results in increased rain chances through the long term. It is
also summer which means CAPE values are forecasted to be between
1000-2000 J/kg every afternoon and evening resulting in increased
thunderstorm chances too. Overall a very summer like pattern. Despite
the increased rain chances most afternoons, accumulations over the
next 7 days range from 0.10"-1.5", so overall still not a lot of
rain. Towards the later half of the long term period (Saturday into
Sunday), models are indicating a break down of the ridging pattern as
a trough dips into the mid MS valley bringing a what looks to be a
frontal pattern. Time will tell how this pattern evolves since it is
still 7 days out.

With the increased moisture, dewpoints will also be increased with
values in the mid 70s through the beginning of next week. This in
addition to the temps reaching into the mid to upper 90s will result
in heat indices being in the 100-106 range Monday. Only minor relief
from these heat indices is expected on Tuesday into Wednesday where
heat indices are currently forecasted below 100, as dewpoints dip
below 70 for a short time period. Moisture surges again Wednesday
returning us to heat indices in the 100-105+ range through the
remainder of the extended. Again overall a very summer like pattern
for much of Georgia as we begin the month of July with above average
temps.

Hernandez

&&

.AVIATION...
(12Z TAFS)
Issued at 722 AM EDT Sat Jun 29 2024

Shower activity has continued to slowly weaken around and N of the
Atlanta metro area. Low cigs are expected to expand over the next
hour or two (along with patchy, mostly light fog near recent rain
areas), with cig heights of around 600-800 feet. Low clouds will
lift and thin later this morning, followed by afternoon shower and
thunderstorm activity. Have adjusted the start time later to account
for morning low clouds and convective debris along with lack of
dynamic support. Light winds will become mostly SW during the day.
Wind speeds will remain light outside of heavier showers and
storms.

//ATL Confidence...12Z Update...
Medium for morning low cigs and vsbys along with start time of
afternoon tstms. High for other elements.

SEC

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          74  95  73  90 /  30  50  40  40
Atlanta         75  94  75  93 /  30  50  30  30
Blairsville     69  88  67  86 /  30  60  20  30
Cartersville    73  94  70  93 /  20  50  20  20
Columbus        75  96  75  96 /  30  60  30  40
Gainesville     75  93  74  90 /  30  50  20  30
Macon           74  96  73  94 /  20  60  40  50
Rome            75  95  72  93 /  20  60  10  10
Peachtree City  73  95  72  94 /  30  50  30  30
Vidalia         75  96  76  94 /  20  60  50  70

&&

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

$$

SHORT TERM...SEC
LONG TERM....Hernandez
AVIATION...SEC