516
FXUS62 KFFC 071900
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
300 PM EDT Tue May 7 2024

...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This afternoon through Wednesday)
Issued at 248 PM EDT Tue May 7 2024

Large 500 mb low is cut off and located over the northern Great
Plains becoming increasingly vertically stacked with surface low in
same area. This storm system was responsible for the severe weather
in the Plains last night, and the organized convection from that has
progressed well ahead of a now stalled cold front and mostly fallen
apart as it pushes through the eastern CONUS. Some convective debris
from that has been traversing the area, and when combined with some
AVA aloft from shortwave ridging, has prevented us from taking off
convectively this afternoon. This is changing into the evening, and
leftover boundary from overnight convection is pushing in, which
could provide a focus from some afternoon showers or thunderstorms,
though expecting these should be very isolated, with best chances to
the north over the higher terrain.

Tonight, moisture continues to push into the area. Some convection
may push in from the west, dependent on whether or not it can get
going over parts of Alabama. North Georgia would be the most likely
to see this per hires guidance. There is a small chance some of this
could be severe for a brief period in far NW GA, as the parameter
space there has decent instability with 40-50 kts of effective bulk
shear. A Marginal Risk (1 out of 5) is in effect for far NW GA as a
result. With sunset, any convection remaining should become
increasingly elevated.

Tomorrow, some hires guidance shows some convection taking place
across northern GA that should be under severe limits, but may have
impacts on overall evolution of convection later in the day.
Guidance shows a piece of the upper level low over the Plains
breaking towards the eastern CONUS as a potent shortwave, allowing
for PVA and decent shear across the CWA Wednesday evening into
Wednesday night. Some general afternoon storms will be possible, but
the bigger "show" may be later in the night and into early Thursday
as a line of storms pushes into northern GA. HRRR and a few other
hires members from this morning show very organized convection with
some UH tracks. This tracks with the parameter space forecasted -
HREF means show MUCAPE of 500-1000+ J/kg still over northern GA by
the early morning hours with 30-40 kts of sfc-500 m shear,
representative of substantial shear within the low levels. This
leads to nearly 100-200 m2/s2 of 0-1 km SRH, which would allow for
ingestion of streamwise vorticity for potential updrafts. Want to
emphasize however that uncertainty remains in how this will evolve -
convective evolution today through tomorrow will have a large
influence on the evolution of the upper levels through diabatic
forcing and the low levels via outflow and other factors. The
environment will be there - it remains to be seen whether any storms
will be able to utilize it.

Lusk

&&

.LONG TERM...
(Thursday morning through next Monday)
Issued at 248 PM EDT Tue May 7 2024

Highlights:

-Potentially active weather will be ongoing at the start of the long
term persisting into Friday.

-Drier weather returns by the weekend persisting into early next
week.

No significant changes with this latest forecast. Still targeting
primarily two rounds of severe potential: the first Wednesday night
into Thursday morning for North GA (1-20 northward) and the second
Thursday evening through early Friday morning for Central Georgia
(south of I-20).

A low pressure system and attendant cold front will be pushing
eastward across the Ohio/TN Valley Regions. This will drive a
complex of showers and thunderstorms, ahead of the front, into the
northern sections of Georgia Thursday morning. Latest hi-res
guidance appears to be slightly quicker with moving this complex
into North GA Thursday morning. The primary threat with any strong
to severe thunderstorms still appears to be damaging winds as a
result of decent deep layer shear and lapse rates accompanying the
complex. Hail and possibly an embedded spin-up tornado are still
threats as well.

This activity will gradually push south through the morning on
Thursday and the question remains if the complex will weaken and/or
be the focus for possible redevelopment during the afternoon as peak
heating occurs. As a reiteration, model guidance typically
struggles with the evolution of convective complexes, thus, still
accounting for some level of uncertainty as far as exact placement
of convective activity beyond Thursday morning. The surface cold
front will still be moving through the forecast area and an
additional surface low looks to develop across the Lower MS
Valley. Latest runs of the 12z hi-res guidance is still picking up
on an additional complex of showers and thunderstorms developing
and translating eastward towards the area Thursday night into
Friday. Again the biggest question will be how this evolves as it
progresses towards the area. Lift from the front, decent lapse
rates, plenty of wind energy in the mid/upper levels accompanying
the main trough may support yet another (third) severe risk late
Thursday into Friday for Central Georgia. Damaging winds and hail
will be the primary hazards for any strong to severe thunderstorms
that develop during the afternoon Thursday or in the evening
through the overnight period. Tornado threat is still fairly low
at this time. Stay tuned for additional updates...

The surface cold front will start to clear the area pushing any
lingering rain/thunder chances out of the forecast area by Friday
afternoon. We return to NW flow aloft with a brief cool down just in
time for the weekend. Some low chance PoPs have been introduced for
next week as some mid-level disturbances look to move through flow
aloft.

07

&&

.AVIATION...
(18Z TAFS)
Issued at 159 PM EDT Tue May 7 2024

VFR to start the TAF period. VFR Cloud cover continues to lift
and scatter across most sites this afternoon and will continue
into the evening, though some SCT040-060 will remain east and west
of ATL. Cigs expected to lower to low MVFR/high IFR tonight
across CSG and metro TAF sites, including ATL during morning
hours, approx 10Z-14Z. Increasing moisture ahead of next system
means BKN cloud cover will likely stick around through afternoon
tomorrow. Some isolated storms will be possible by afternoon hours
as well. Winds will be SW from 5-10 kts through TAF period.

//ATL Confidence...18Z Update...Large 500 mb low is cut off and located over the northern Great
Plains becoming increasingly vertically stacked with surface low in
same area. This storm system was responsible for the severe weather
in the Plains last night, and the organized convection from that has
progressed well ahead of a now stalled cold front and mostly fallen
apart as it pushes through the eastern CONUS. Some convective debris
from that has been traversing the area, and when combined with some
AVA aloft from shortwave ridging, has prevented us from taking off
convectively this afternoon. This is changing into the evening, and
leftover boundary from overnight convection is pushing in, which
could provide a focus from some afternoon showers or thunderstorms,
though expecting these should be very isolated, with best chances to
the north over the higher terrain.

Tonight, moisture continues to push into the area. Some convection
may push in from the west, dependent on whether or not it can get
going over parts of Alabama. North Georgia would be the most likely
to see this per hires guidance. There is a small chance some of this
could be severe for a brief period in far NW GA, as the parameter
space there has decent instability with 40-50 kts of effective bulk
shear. A Marginal Risk (1 out of 5) is in effect for far NW GA as a
result. With sunset, any convection remaining should become
increasingly elevated.

Tomorrow, some hires guidance shows some convection taking place
across northern GA that should be under severe limits, but may have
impacts on overall evolution of convection later in the day.
Guidance shows a piece of the upper level low over the Plains
breaking towards the eastern CONUS as a potent shortwave, allowing
for PVA and decent shear across the CWA Wednesday evening into
Wednesday night. Some general afternoon storms will be possible, but
the bigger "show" may be later in the night and into early Thursday
as a line of storms pushes into northern GA. HRRR and a few other
hires members from this morning show very organized convection with
some UH tracks. This tracks with the parameter space forecasted -
HREF means show MUCAPE of 500-1000+ J/kg still over northern GA by
the early morning hours with 30-40 kts of sfc-500 m shear,
representative of substantial shear within the low levels. This
leads to nearly 100-200 m2/s2 of 0-1 km SRH, which would allow for
ingestion of streamwise vorticity for potential updrafts. Want to
emphasize however that uncertainty remains in how this will evolve -
convective evolution today through tomorrow will have a large
influence on the evolution of the upper levels through diabatic
forcing and the low levels via outflow and other factors. The
environment will be there - it remains to be seen whether any storms
will be able to utilize it.

Medium-high morning cigs, high all others.

Lusk

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          68  88  69  84 /  10  30  40  80
Atlanta         69  87  69  85 /  20  30  50  90
Blairsville     64  82  63  78 /  40  60  80  90
Cartersville    67  87  66  83 /  30  40  60  80
Columbus        70  91  72  89 /  10  20  20  80
Gainesville     69  86  69  82 /  30  50  60  90
Macon           69  90  70  89 /   0  10  10  70
Rome            68  87  67  85 /  40  50  70  90
Peachtree City  69  89  69  86 /  10  20  30  80
Vidalia         69  92  71  92 /   0  10  10  50

&&

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

$$

SHORT TERM...Lusk
LONG TERM....07
AVIATION...Lusk