992
FXUS62 KFFC 180814
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
414 AM EDT Sat May 18 2024


...Morning Area Forecast Discussion...

.SHORT TERM...
(Today through Sunday)
Issued at 411 AM EDT Sat May 18 2024

Much of the Southeast CONUS remains under enhanced southwesterly
upper level flow ahead of a shortwave trough advancing into the
Lower Mississippi River Valley region. Meanwhile, a strong upper
level jet streak is present within the southwesterly flow aloft,
which extends from the central Gulf Coast into the Appalachians.
Showers and thunderstorms have developed across portions of central
and south Alabama and underneath the right-rear quadrant of this
upper jet. These storms will advance eastward, and more convection
will fire near remnant outflow from the MCS that decayed over south
Georgia last night. As such, rain chances will steadily from
southwest to northeast through the early morning hours, with likely
PoPs forecast in portions of west-central Georgia and chance PoPs
elsewhere across the forecast area this morning and into the early
afternoon.

Low cloud ceilings and patchy are in place across much of the
forecast area as the morning begins. Low temperatures and dewpoints
will start the morning primarily in the mid 60s. With ample moisture
the boundary layer, thunderstorms this morning will have MLCAPE
values of as high as 1000-1500 J/kg to work with in portions of
central Georgia. Furthermore, the influence of the jet streak will
contribute to deep layer bulk shear values of 40-60 kts. 0-1 km
shear values are also anticipated to range from 20-25 kts. These
environmental parameters, along with the orientation of the
aforementioned shear in association with the jet streak, will allow
some thunderstorms to become organized into linear clusters capable
of producing damaging wind gusts. This is anticipated to become more
likely after sunrise, with diurnal heating leading to increasing
surface-based instability.

Speaking of afternoon heating, broken to overcast cloud coverage is
forecast to persist across the majority of the forecast area today.
As such, high temperatures are expected to remain confined to the
mid to upper 70s across the majority of the area. Still, with
dewpoints increasing into the upper 60s by this afternoon, SBCAPE
values are forecast to increase to 1500-2500 J/kg during the peak
heating hours this afternoon. Later this afternoon, the axis of the
shortwave will approach north Georgia, which will provide forcing
for another round of showers and thunderstorms starting in the far
northern tier. With similar shear profiles from this morning, and
also mid-level lapse rates of 6.5-7 C/km, a few of these storms will
also have the potential to become strong to severe, capable of
producing damaging wind gusts and hail. These storms are forecast to
advance southward during the late afternoon and into the evening, at
which point they will begin to diminish in coverage after sunset
with the loss of diurnal heating.

A caveat to keep in mind is that the behavior and evolutions of this
round of storms will depend on how the airmass recovers after storms
earlier in the day. Furthermore, with precipitable water values
expected to range from 1.5 to 1.8 inches, stronger storms that occur
today are expected to be efficient rainmakers, which could cause
localized flooding concerns where storms train over a common
location. During the overnight hours, the trough axis itself will
move southeastward through Georgia, with the best forcing and
dynamics remaining ahead of the trough. By Sunday morning, the
trough will begin to move offshore of the Georgia coast and into the
Atlantic. The associated vorticity couplet will still be positioned
over eastern Georgia. Combined with a weak moisture axis, this will
result in showers once again on Sunday, with the highest coverage
focused over the eastern portion of the forecast area. Lift in the
vicinity of the trough axis, combined with diurnal instability, will
be sufficient for the development of scattered thunderstorms among
the showers on Sunday. At this time, severe weather is not expected
on Sunday, although an isolated storm cannot be ruled out.

King

&&

.LONG TERM...
(Sunday night through Friday)
Issued at 411 AM EDT Sat May 18 2024

Sunday evening, we should be seeing the end of our active and wet
weather coming to an end as any remaining showers and thunderstorms
should be tapering off. As the upper level trough and surface low
push off the eastern seaboard, a ridge axis aloft will begin to
orient itself along the spine of the Appalachians and a surface
high will settle in along the lee of the mountains. As the ridge
axis shifts east to become established Monday, a few terrain
induced afternoon showers and thunderstorms may fire across the
northeast Georgia mountains. Otherwise, generally benign and dry
weather conditions are expected outside of these location`s.
There`s still model spread (~5 degrees) in the guidance over the
maximum daytime temperature on Monday, particularly across eastern
Georgia where temperatures will be moderated depending on how far
southwest the extent of the wedge can become established and
whether or not any afternoon storms can get going in the
mountains. Temperatures Monday will be the coolest of the week
with highs in the low to mid 80s for most locations outside of
higher elevations. Temperatures will become more summer-like by
Tuesday with highs in the mid 80s nearly areawide. A gradual
warming trend will continue through the end of the forecast period
into the upper 80s with some locations across southern central
Georgia reaching the 90 degree mark. While the first half of the
long term forecast will be largely dry, a low amplitude shortwave
traversing the Plains will push a weak and diffuse boundary
towards north Georgia, bringing the chance for rain back into the
fold. Chance PoPs are introduced for north Georgia Wednesday where
showers and a few thunderstorms will be possible. As the weak
boundary sags south and becomes quasi-stationary, showers and
thunderstorms will develop along the boundary across north and
much of central Georgia as some weak disturbances in the quasi-
zonal flow pass through. While no severe weather is expected at
this time, instability around 500-1000 J/kg, steep midlevel lapse
rates and modest shear could produce a few strong storms Thursday
and Friday.

KAL

&&

.AVIATION...
(06Z TAFS)
Issued at 144 AM EDT Sat May 18 2024

Ceilings are primarily MVFR across north and central Georgia, and
gradually lowering. Ceilings are forecast to lower to mainly IFR
in the next couple of hours, although a drop to LIFR is looking
less likely than the previous forecast. Scattered -SHRA is
spreading into west and central Georgia, and is expected to
increase in coverage and spread north during the early morning
hours. As a cold front advances towards north Georgia, it will
send a broken line of organized SHRA/TSRA into north Georgia,
which will work its way southward in the late afternoon and
evening. A PROB30 for TSRA has been maintained for the northern
TAF sites as a result. Winds will be S to SW at 5 kts through the
early morning hours, becoming SW at 5-8 kts by 13Z and through the
remainder of the day.

//ATL Confidence...06Z Update...
Medium confidence on all elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          79  63  78  59 /  50  30  50  10
Atlanta         79  64  79  62 /  60  40  50  10
Blairsville     75  59  75  57 /  60  50  60  10
Cartersville    78  62  80  60 /  60  50  40   0
Columbus        79  65  83  64 /  60  30  40  10
Gainesville     77  63  78  61 /  60  40  50  10
Macon           79  65  80  62 /  60  30  50  10
Rome            79  61  83  61 /  70  50  30   0
Peachtree City  80  64  80  61 /  50  40  50  10
Vidalia         81  68  81  64 /  70  40  70  20

&&

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

$$

SHORT TERM...King
LONG TERM....KAL
AVIATION...King