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FXUS62 KFFC 040202 AAB
AFDFFC

Area Forecast Discussion...UPDATED
National Weather Service Peachtree City GA
1002 PM EDT Wed Jul 3 2024



...Evening Update...

.UPDATE...
Issued at 947 PM EDT Wed Jul 3 2024

Isolated showers have largely come to an end across central
Georgia this evening. Nighttime Microphysics satellite imagery
shows mid-level clouds (debris from earlier convection) with no
vertical growth. Have added patchy fog to the forecast overnight
into early tomorrow (Thursday) morning mainly along and south of
I-20 after looking at visibility guidance. Otherwise, little to no
change has been made to the forecast.

Martin


&&

.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...
(00Z TAFS)
Issued at 733 PM EDT Wed Jul 3 2024

Isolated SHRA will persist south of I-20 for the next few hours.
VFR conditions are expected at the northern TAF sites overnight,
while at MCN and CSG and across portions of central GA, MVFR/IFR
cigs and MVFR vsby are expected after 08z until around 13z. Winds
will be calm to light and SSE overnight, becoming SSW by around
15z tomorrow (Thursday) at 3-7 kts. All sites except for MCN have
a PROB30 tomorrow afternoon for TSRA. SHRA/TSRA are expected to be
isolated to scattered with an afternoon Cu field.

//ATL Confidence...00Z Update...
Medium confidence on timing of wind shift and cigs/vsby at MCN
and CSG. High confidence on all other elements.

Martin


&&

.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...Martin