687
FXUS62 KFFC 031913
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
313 PM EDT Wed Jul 3 2024


...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This evening through Thursday)
Issued at 312 PM EDT Wed Jul 3 2024

An upper level ridge continues to extend from the north-central Gulf
of Mexico northeastward along the Atlantic coast. As associated
surface high pressure moves away to the northeast, the wedge pattern
over north Georgia continues to weaken. As temperatures warm and
lingering cloud cover begins to scatter out, showers and
thunderstorms have begun to develop roughly south of I-20. PoPs this
afternoon are forecast to be highest across west-central Georgia,
where dewpoints are in the mid 70s and low-level moisture is most
ample. A gradual warming trend is also ongoing under the influence
of the aforementioned ridge. Aside from highs in the 80s in the
higher elevations of far northeast Georgia, highs are forecast to be
in the low to mid 90s this afternoon. MUCAPE values through the
remainder of the afternoon are forecast to range from 1000-1500 J/kg
roughly south of I-20. These instability values will be sufficient
for continued convection. With vertical profiles indicating tall but
thin CAPE profiles and very limited shear, the threat for severe
weather this afternoon are expected to remain below severe limits.
With slow storm motion and precipitable water values between 1.6-2
inches, a few storms may produce locally heavy rain. Precipitation
chances will diminish after sunset.

For the 4th of July, low temperatures are forecast to start the
morning mainly in the mid 70s. Overnight and into the morning,
continued southerly flow will bring in more Gulf moisture, and low
level moisture and dewpoints in the mid 70s will continue to spread
northward. Furthermore, the warming trend will continue, with
temperatures rising into the mid to upper 90s across much of the
area. The combination of hot temperatures and abundant moisture will
allow for heat index values to reach critical thresholds of 105
degrees in many locations. A Heat Advisory remains in effect for
the forecast across north and central Georgia from 1 PM until 7 PM
tomorrow, with the exception of far northeast Georgia where heat
indices will be well outside of criteria. Diurnally-driven
thunderstorms are expected once again on Thursday afternoon.
Highest PoPs are forecast across the southwest portion of the
forecast area and the lowest PoPs are forecast in the far eastern
portion of the area where a strong cap could potentially inhibit
widespread convective development. While an organized threat for
severe thunderstorms is not expected, a few storms could become
strong and produce locally heavy rain and frequent lightning.
Considering high precipitable water values, water loading in
downdrafts of stronger storms could also produce gusty winds.

King

&&

.LONG TERM...
(Friday morning through next Tuesday)
Issued at 312 PM EDT Wed Jul 3 2024

Key Messages:

 - Hot and humid conditions will keep portions of northern and
central Georgia Georgia on the cusp of Heat Advisory thresholds
through the weekend.

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

An Outlook for the Weekend:

Hot and humid conditions will remain the primary weather concern
this weekend. Weak upper level ridging stretching from the Gulf
coast to the Carolinas and rising 850 mb temperatures (to ~21 C)
should contribute to gradual increases in ambient surface
temperatures (mid and upper 90s). However the real kicker for the
heat should be rising surface dewpoints driven by moisture advection
ahead of a weak cold front. Widespread dewpoints in the lower 70s
are anticipated in the state on Friday. Over the weekend dewpoints
should become more bifurcated (spit by the front) with upper 60s and
lower 70s in northwest Georgia and mid 70s in east central Georgia.
The elevated surface dewpoints should produce oppressive humidity
and push heat indices into the triple digits south of the front.
Widespread heat index values of 102 to 108 degrees are anticipated
on Friday. Then on Saturday and Sunday the highest values (105 to
110 degrees) should become more focused over central and eastern
Georgia. A Heat Advisory may be needed for portions of northern or
central Georgia on Friday (30% chance). Then over the weekend a Heat
Advisory is likely (60% chance) for portions of central Georgia. The
forecast position of the frontal boundary (near Interstate 85)
suggest a low probability (20%) of a Heat Advisory for the Atlanta
Metro over the weekend. An important caveat to keep in mind for the
heat forecast is that in lingering cloud cover from convection could
hold temperatures down and reduce the need for any Heat Advisories.

The second portion of the forecast to monitor over the weekend will
be the rising thunderstorms chances. Severe thunderstorms are
unlikely due to limited shear and modest 700-500 mb lapse rates
(~5.5 C/km) along and ahead of the front. That said, surface hinder
the temperature forecast convergence along the front and decreasing
mid level subsidence should support more widespread diurnally driven
thunderstorm activity Friday, Saturday and Sunday. More isolated
activity may occur during the overnight hours each day. Elevated PW
values, near or above 2 inches (90th percentile for early July),
should support rain rates of 1 to 3 inches per hour with the
strongest convection. This could produce some isolated flooding
concerns, especially Saturday afternoon and evening.

Considerations of Early Next Week:

Guidance from the EPS and GEFS suggests a broad area of troughing
from the Great Lakes to the Central Plains early next week. With
weak ridging favored over the Western Atlantic, this should lead to
weak flow aloft and minimal subsidence over Georgia. Though the
higher PW airmass that moved in over the weekend may moderate some
on Monday, moisture and humidity should generally linger in the
region. The combination of these two factors should allow scattered
afternoon and evening thunderstorm activity to linger in the region
early next week. Temperatures in the region should remain relatively
unchanged, with widespread highs in the low to mid 90s continuing to
push heat index values into the 98 to 105 degree range.

Albright

&&

.AVIATION...
(18Z TAFS)
Issued at 130 PM EDT Wed Jul 3 2024

Isolated SHRA/TSRA has begun to develop to the south of I-20, and
is expected to increase in cover through the mid-afternoon.
Ceilings have lifted to VFR, between 030-050, across the majority
of the area. Ceilings will continue to lift and scatter into
tonight. IFR ceilings and patchy fog will be possible in central
Georgia and MCN/CSG during the early morning hours, between
10-14Z. Winds will be primarily SE at 4-8 kts through much of the
period, shifting to SW on Thursday morning.

//ATL Confidence...18Z Update...
Medium confidence on timing of the wind shift.
High confidence on all other elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          73  97  75  96 /  10  20  10  50
Atlanta         75  93  77  94 /  10  40  20  60
Blairsville     68  90  71  88 /  10  30  30  80
Cartersville    73  95  74  94 /  10  40  30  80
Columbus        76  94  77  95 /  30  60  40  60
Gainesville     73  95  76  94 /  10  20  10  60
Macon           74  95  75  95 /  30  30  20  50
Rome            75  96  76  95 /  10  40  20  80
Peachtree City  73  94  74  94 /  20  40  20  60
Vidalia         74  94  74  96 /  30  30  20  40

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM to 7 PM EDT Thursday for GAZ001>005-011-
012-019>021-024-025-027-030>039-041>062-066>076-078>086-089>098-
102>113.

&&

$$

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