-- Discussion containing changed information from previous version are highlighted. --
794
FXUS62 KFFC 231039
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
639 AM EDT Sun Jun 23 2024



...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Monday)
Issued at 348 AM EDT Sun Jun 23 2024

At a glance:

    - Unseasonable warmth continues

    - Mostly dry today, low-end rain chances pick up overnight

A bit of a pattern change is underway in the mid-levels, with our
presiding ridge retrograding westward over the course of the day
today, being replaced by the southern fringes of a trough digging
across southern Canada and the Great Lakes. The remnants (both
residual forcing and associated moisture) of Invest 92L did not make
much inland progress on Saturday, due in part to a strong dry layer
aloft -- depicted well by the capping inversion at 650mb on the
23/00Z sounding. As a result, rain chances today will be relegated
to areas east of a line extending from Athens to Macon, in closest
proximity to lingering tropical moisture (PWATs north of 1.7"). Even
so, only isolated to widely scattered thunderstorms are forecast (20-
40% chances), with rainfall totals likely to be less than a tenth to
a quarter of an inch.

Rain chances will return to north Georgia for the first time in
several day late this evening and overnight, associated with a pre-
frontal trough. Moisture associated with this boundary is meager at
best, and will be fighting a losing battle against our current
airmass: one that has warmed and dried under multiple days of
subsidence under the aforementioned mid-level ridge. A patchy, quasi-
line of showers and thunderstorms looks to enter northwest Georgia
after sunset tonight and make its way southeastward through daybreak
Monday morning -- producing rainfall totals unlikely to breach more
than a quarter of an inch.

The main story through the short term continues to be the building
heat and rising temperatures. Highs today and tomorrow afternoon are
forecast to surge well into the mid-to-upper 90s, and the century
mark is within reach across the Columbus and Macon areas. Currently,
the national blend (NBM) progs a 30-40% chance for central Bibb
County to make it to 100 degrees today and Monday. The only saving
grace of our current setup continues to be strong mixing (with
mixing heights up to ~8000ft/~750 mb) tamping down dewpoints and
moisture, preventing heat from creeping into oppressive levels.
Maximum heat index values will be nearly equal to highs as a result,
but may reach as high as 101-103F across the southern half of the
area. Continue to exercise caution if spending long periods of time
outside, take frequent hydration breaks in the shade, and always
look before you lock.

96

&&

.LONG TERM...
(Monday night through Saturday)
Issued at 348 AM EDT Sun Jun 23 2024

As the long term period picks up on Monday night, an upper level
trough and associated surface low over New England will be moving
northeastward towards Nova Scotia while ridging setting up over the
Midwest places much of the eastern CONUS in northwesterly upper
level flow. A cold front extending from the low will be positioned
over north Georgia and gradually sinking southward. Some isolated
showers and thunderstorms will be possible ahead of the front,
mainly in east-central Georgia before coming to an end by midnight.
Surface high pressure underneath the ridge will begin to build into
the region overnight and into Tuesday. Low temperatures on Tuesday
morning will drop into the upper 60s across much of far north
Georgia, and into the low to mid 70s. Drier conditions are
anticipated under the high and underneath the northwesterly flow
aloft, with dewpoints anticipated to be in the low 60s. The drier
air underneath this pattern will be short-lived, as scattered
diurnally-driven thunderstorms will return to central Georgia on
Tuesday afternoon.

It will be important to keep an eye on temperatures throughout much
of the week. NBM and some other guidance continues to show very hot
temperatures across the majority of the forecast area. For this
forecast package, I once again elected to blend in some NBM10percent
into the high temperature guidance to account for models potentially
overmixing and impacts from convective development. As convective
temperatures are reached and storms subsequently develop, the rain
and increased cloud cover can often prevent us from reaching such
scorching temperatures. In any case, high temperatures are still
forecast to rise into the mid to upper 90s across the majority of
the forecast area, and some locations in east-central Georgia could
exceed 100 on Tuesday and Wednesday. Even with trending high
temperatures down, these highs are still forecast to range from
between 6-12 degrees above average for late June. Heat indices are
forecast to creep up into the triple digits in many locations,
particularly in the southern half of the forecast area, and heat
products may be warranted. Overnight temperatures in the mid to
upper 70s will also not provide much in the way of relief from the
heat.

By Wednesday morning, a longwave trough is expected to extend into
the Mississippi River Valley and move eastward towards Georgia over
the course of the day. Some uncertainty still remains with respect
to the timing of this feature, although confidence is increasing
that the trough and an associated weakening surface frontal boundary
will being increased chances for thunderstorms to the area late
Wednesday into Thursday, with high-end chance to low-end likely PoPs
forecast during that timeframe. Southerly low-level flow will likely
return to the area Friday into Saturday, which will promote
increasing dewpoints and temperatures once again going into next
weekend.

King

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 629 AM EDT Sun Jun 23 2024

Primarily VFR conds to continue thru the TAF pd. FEW-SCT cu at
5-8kft to develop between 14-16Z. Winds initially light (5kts or
less) out of the SSW will shift to the W/WNW by 13-14Z at 6-9kts.
Low-end gusts to 12-15kts are psbl this aftn. Late period, low-
end chcs for isold -SHRA or -TSRA and low-VFR to MVFR cigs and
vsbys at northern TAF sites from 08-12Z Monday.


//ATL Confidence...12Z Update...
Medium confidence Monday morning precipitation chances.
High confidence all other elements.

96
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Athens          75  97  70  96 /  20  10  10  10
Atlanta         77  97  74  97 /  30  20   0  10
Blairsville     68  88  62  89 /  30   0   0  10
Cartersville    73  96  68  97 /  30  10   0  10
Columbus        76  99  74 100 /  10  20  10  20
Gainesville     75  94  70  94 /  20  10   0  10
Macon           75 100  73 100 /  10  30  10  20
Rome            73  97  69  98 /  30   0   0  10
Peachtree City  75  98  71  98 /  20  20  10  10
Vidalia         78  99  77  99 /   0  20  20  50
-- End Changed Discussion --

&&

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

$$

SHORT TERM...96
LONG TERM....King
AVIATION...96