367
FXUS62 KFFC 081753
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
153 PM EDT Mon Jul 8 2024

...New 18Z Aviation Discussion...

.UPDATE...
Issued at 1147 AM EDT Mon Jul 8 2024

Clouds have been slow to thin and erode across the E central portion
of the area this morning. As a result, this has delayed the rise in
temperatures expected. Nevertheless, once clouds do thin, high
temperatures and heat indices are still forecast to occur. As a
result, no significant changes to the forecast are expected at this
time. Differential heating near the edge of the thicker cloud cover
may provide enough forcing to get convection going first this
afternoon. /SEC

&&

.SHORT TERM...
(Today through Tuesday)
Issued at 449 AM EDT Mon Jul 8 2024

Key Messages:

  - Heat Advisory is in effect for central and eastern GA from 11 am
    to 8 pm. Heat indices above 105 will be possible.

  - Diurnal convection is expected to be more suppressed today.
    This is part of why heat advisory was issued, as convective
    debris will be less present. Still, some afternoon storms will be
    possible across north and central Georgia, a few of which could
    be strong.

Forecast:

A few showers and thunderstorms continue to progress through east
central Georgia this morning thanks to what is left of MCS that
pushed through eastern portion of the state last night. In the wake
of the MCS we are seeing some very patchy fog and low cloud ceilings
this morning. Not anticipating fog to become widespread enough for
any product issuance, but will continue to monitor.

Today, hi res guidance is showing relatively little afternoon
convection compared to previous days (with the exception of the FV3,
but it looks quite overdone). Several factors seem to back up a
lower coverage solution - overnight MCS has worked over good portion
of the area that will take some time to recover to start. This will
likely help delay onset of convection. In addition, the pattern is
favoring some mid level subsidence, with cut off low to the east and
Beryl making landfall to the west and moving north, well away from
the CWA. All this said, moisture is copious. PWATs remain very high
across much of north and central Georgia (2+") and surface dewpoints
are surging well into the 70s yet again this afternoon. Convective T
will still be achievable, so some afternoon thunderstorms are
expected. Shear remains practically non-existent at less than 20
kts 0-6km and the moist adiabatic profiles are not conducive to
impressive lapse rates, so not expecting much severe weather, but
a strong thunderstorm or two will still be possible. Heavy
rainfall rates will again be a concern, and similar to today,
storms will be capable of 1-2+" an hour rates, which will be
capable of some flash flooding under the right conditions.

Given the aforementioned reduced coverage of precipitation today,
heat advisory is necessary in part of central and eastern GA. Most
areas in the advisory will approach heat indices at or above 105 by
the afternoon. WBGT values are also quite elevated in this area,
between 88-90, demonstrating how high the humidity is. Please use
caution if working or exercising outdoors. See advisory for more
information.

Tomorrow looks very similar to forecast for today. Convection
looks to be limited thanks to some subsidence present as what will
be the remnants of Beryl slides to the NW of the CWA. It looks to
be just as hot and humid, so heat advisories may be necessary
again. Have chosen to substantially lower PoPs compared to
multimodel statistical ensemble (NBM).

Lusk

&&

.LONG TERM...
(Tuesday night through Sunday)
Issued at 449 AM EDT Mon Jul 8 2024

At the onset of the extended forecast period on Wednesday, the
remnants of Beryl will be lifting well to our north from the Ohio
Valley into the Great Lakes region. As this occurs, considerably
drier air will wrap southward in its wake into the forecast area.
Dewpoints in the 60s and associated drier precipitable water values
of 1 to 1.5" (and perhaps even sub 1") will filter into much of the
state from Wednesday into Thursday. In the presence of this
considerably drier airmass, PoPs will be on a significant downward
trend on both Wednesday and Thursday. PoPs were adjusted a bit below
NBM with this trend likely to continue over the coming forecast
cycles. From Friday into the weekend, mainly isolated to widely
scattered diurnal PoPs are favored given no focus for any widespread
increase in coverage.

The infiltration of the aforementioned drier airmass will also
provide a welcome relief from the stifling, swampy conditions of
late. Daytime highs will dip slightly by Wednesday and Thursday, but
the most noticeable impact will be lower heat index values amid more
tolerable dewpoints. In fact, by Thursday into Friday, triple digit
heat index values will likely be virtually eliminated across the CWA
- a welcome change. Additionally, morning lows in the 60s are
increasingly likely across north Georgia by Thursday and Friday,
which would feel practically fall-like as compared to recent
conditions.

RW

&&

.AVIATION...
(18Z TAFS)
Issued at 145 PM EDT Mon Jul 8 2024

Have generally left the timing of thunderstorms intact for the
Atlanta metro area today. Opted to reduce thunder at AHN to a few
hours of VCTS after 01Z. Made some adjustments to thunderstorm timing
at both CSG and MCN (starting at 20Z and 22Z respectively). Also
included a tempo BKN for low cigs Tue morning at all sites). Winds
will be very light, but generally SSE for the rest of today and SSW
for Tue morning. At ATL, opted to keep SSE winds into the early
evening, then a very light SSW wind thereafter. There will be periods
later this afternoon when SSW mix down, but feel SSE will
predominate.

//ATL Confidence...18Z Update...
Medium for exact wind direction this afternoon and early evening,
start and end time for thunderstorms, and morning cigs. High for all
other elements.

SEC

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          74  95  75  94 /  30  50  30  40
Atlanta         76  94  76  92 /  30  50  20  30
Blairsville     69  88  70  86 /  30  60  30  60
Cartersville    74  95  74  91 /  20  50  30  40
Columbus        76  96  77  94 /  30  50  10  40
Gainesville     74  93  75  91 /  30  50  40  40
Macon           74  95  76  94 /  20  40  10  40
Rome            74  95  75  90 /  20  50  30  40
Peachtree City  74  95  74  93 /  30  40  20  30
Vidalia         76  94  76  94 /  30  60  20  60

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT this evening for GAZ036>039-047>051-
058>062-066>076-078>086-089>098-102>113.

$$

SHORT TERM...SEC
LONG TERM....RW
AVIATION...SEC