181
FXUS62 KFFC 081739
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
139 PM EDT Wed May 8 2024

...New 18Z Aviation Discussion...

.SHORT TERM...
(Today through Thursday)
Issued at 343 AM EDT Wed May 8 2024

Challenging forecast for the entire short term period.

Weak high pressure remains in place across the CWA this morning. A
nearly stationary frontal boundary stretches from the central Great
Lakes back through central Texas. A warm front is situated across the
northern Mid Atlantic States. All of the SE US and Gulf States
remain within the warm sector with an atmosphere very conducive for
convection through the short term period. However, timing/coverage is
HIGHLY dependent on upstream convection/potential MCS development.
Earlier today should be fairly quiet with thunderstorm potential
increasing this evening and lasting well into Thursday.

500mb analysis shows shortwave ridging beginning to move offshore.
One mid level low is across the upper Plains states and the second is
across the central Great Lakes. The Great Lakes low is expected to
move eastward across New England and the upper Plains slow will move
east-southeast through the period. The main energy with these two low
pressure systems should remain well to the north of the CWA.
However, models are progging a strong shortwave to drop southeast
overnight Wednesday into early Thursday. Thickness values during this
time definitely indicate the potential for a MCS moving across
portions of the CWA.

Since most of the convection during the short term period is
dependent upon upstream activity and any development of an MCS, the
forecast will be very challenging. The models have been fairly
consistent from run to run showing an MCS dropping southeast from the
TN Valley late Wednesday/early Thursday morning. However, not quite
sure the hi-res models have a great handle on the evolution of this
system. The HRRR has a couple of distinct waves of convection, with
one them the MCS in question. The waves of convection are fairly
close together and an earlier system could definitely impact the
evolution of a later system. The first system could move SE across
northern portions of the state Wednesday evening and into the
overnight hours. A secondary wave of convection is progged to
approach northern portions of the state early Thursday morning, near
12Z...potentially the main MCS. This system moves southeast across
much of the CWA during the day. The evolution of this system is VERY
dependent upon any earlier convection.

If the evening/overnight wave holds together and does impact
portions of north/northeast GA, this area could get worked over
fairly well before the main MCS moves through. However, if the wave
doesn`t hold together, northeast portions of the CWA will have the
same potential for severe weather the remainder of the CWA when the
main MCS is forecast to move through. Do think the potential for
hazardous weather will be greater with the main MCS that begins to
move through early Thursday morning and continues southward through
the day.

All of the parameters will be there for severe thunderstorms with
any waves/MCS that impact the CWA overnight and early Thursday. There
will be plenty of moisture, forcing, shear and instability. Mid
level lapse rates are impressively steep. The primary hazards for
severe thunderstorms haven`t changed from previous days, but timing
will be somewhat difficult to nail down until these systems actually
develop and are able to sustain themselves. Generally, think the best
chances for more widespread storms/severe will be with the main MCS
push. Any activity that develops ahead of the main MCS will also have
the potential to become severe, but maybe not have the potential to
be as widespread. Damaging wind gusts and large hail will be the
primary hazards. There will also be potential for tornadoes. Locally
heavy rainfall is a given.

NListemaa

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 343 AM EDT Wed May 8 2024

A cold front will be situated across north Georgia at the start of
the period Thursday night. There may be some ongoing convection
within the area during this time, dependent on how development trends
evolve Thursday afternoon. The focus for later Thursday night into
Friday morning will then turn to the potential for an MCS that could
approach from the west. A shortwave will initiate convection across
east Texas into Louisiana which may congeal into a convective complex
and race eastward Thursday evening through early Friday morning as
supported by much model guidance. Still, uncertainty remains
regarding this scenario as well as the track of said convective
complex if it occurs; however, SBCAPE and bulk shear parameters would
be supportive of a damaging wind threat if this scenario manifests.
The areas most likely to experience impacts in this case would likely
be our Middle Georgia counties and points southward to the Gulf
Coast.

The cold front will make further southward progress on Friday,
shunting lingering PoPs largely to southern portions of the CWA by
the afternoon. Some potential for strong to isolated severe may
remain Friday afternoon in southern zones, though this will depend to
some degree on how any morning MCS impacts evolve. By Friday
evening, the front should finally clear the area and put an end to
the rainfall. In the wake of the front, northwest flow aloft will
persist through the weekend while high pressure builds in at the
surface. A noticeably drier and cooler airmass will bring
temperatures slightly below to near normal through the weekend.

Drier conditions may be relatively short-lived, however, as high
pressure departs eastward by Monday and southerly low-level flow
returns. An approaching shortwave will begin to increase PoPs to our
west on Monday, and trends may support PoPs higher than currently
forecast by Monday in future forecast cycles. An unsettled pattern
then looks likely to continue thereafter.

RW

&&

.AVIATION...
(18Z TAFS)
Issued at 126 PM EDT Wed May 8 2024

Thick MVFR cigs across much of the area have lifted above 3kft, and
the area has shifted en masse ENE away from several of the Atlanta
area terminals. These clouds should continue to erode from the edges
with more breaks in the middle. However, this necessitated a cig
(VFR) at AHN. Winds will be generally light out of the SW through the
evening. The focus will then shift to thunderstorms sinking S into
the area overnight tonight. Some of these storms may be strong to
severe, with the threat of gusty winds and hail. Have bumped up the
wind speeds/gusts in storms along with reducing vsbys and cig
heights. These elements may need to be further worsened as
confidence increases.

//ATL Confidence...18Z Update...
Medium for exact timing of thunderstorms (along with accompanying
conditions), high for other elements.

SEC

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          69  81  64  81 /  40  60  30  30
Atlanta         70  80  66  78 /  40  70  40  30
Blairsville     64  77  57  71 /  70  70  30  20
Cartersville    67  82  60  78 /  60  70  40  20
Columbus        73  85  68  84 /  20  70  50  50
Gainesville     69  80  65  78 /  50  70  30  30
Macon           71  85  66  83 /  20  70  40  50
Rome            68  83  62  78 /  80  80  30  20
Peachtree City  70  81  63  81 /  30  70  50  30
Vidalia         72  90  70  84 /  20  60  50  70

&&

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

$$

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