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FXUS62 KFFC 061853
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
253 PM EDT Mon May 6 2024


...Afternoon Area Forecast Discussion...

.SHORT TERM...
(This afternoon through Tuesday)
Issued at 251 PM EDT Mon May 6 2024

Notable shortwave is currently traversing the southeastern CONUS
with remnant outflow boundary from this morning`s convection
stationed over northern GA. Deep layer moisture is punching in ahead
of the shortwave in a region of strong PVA across northern and
eastern GA, allowing for some steepening lapse rates under a region
of broad ascent with the afternoon sunshine. Isolated storms are
already firing across northern GA with some focus along the terrain,
though so far these are certainly feeling our somewhat worked over
environment aloft and haven`t lasted too long, despite 15-25 kts of
bulk shear analyzed on the SPC mesoanalysis. A more impressive
storm is going in Jefferson County where a differential heating
boundary is likely aiding in convective initiation. Expect
isolated storms to continue through the evening hours, with
slightly higher coverage possible in parts of northern GA. A
Marginal (1 out of 5) risk has been issued for northern GA. The
primary threats are isolated large hail and damaging winds.
Continued afternoon heating will allow for MLCAPE values to rise
into the 1500-2000 J/kg range, which combined with effective bulk
shear values of 20-25 kts as the shortwave continues to move
through should allow for a few storms that could become more
organized. The tornado threat isn`t zero, but it is very low -
overall forecast soundings show that low level shear struggles to
be streamwise in nature, so a mesoscale accident along a boundary
would likely be necessary.

Tonight, the shortwave is expected to move by and this should help
suppress the continuation of any convection as region of AVA
moves in and shortwave ridging builds. Concerns tonight will be
how much rain falls today and how much clearing occurs to allow
for some potential vsby and low ceiling issues. Currently have
kept any haze or fog out of the forecast, but this could change
tonight.

Tomorrow, the shortwave ridging is expected to remain in place
over the area during the morning hours ahead of the next system
ejecting out of the Plains. This should help keep things in check
as far as convection goes for part of the day. However, strong jet
streak within an elongating jet over the CONUS will move to the
NW of the area, driving height falls and push a cold
front/convective outflow into the SE during the afternoon. Some
hires guidance redevelops convection along this and pushes into NW
GA by the evening hours. This seems like a realistic scenario,
though it will certainly be impacted in part by the convective
evolution with the Great Plains this afternoon and tonight.
Diabatic pumping of the downstream ridge combined with the strong
PV gradient along the jet/jet streak is leading to multiple rossby
wave breaks, which is known to be a struggle for models to
properly capture.

PoP chances have been concentrated over northern GA as a result of
all this, with a Marginal Risk (1 out of 5) currently in place. A
tongue of instability will creep into portions of northern GA with
HREF showing means of 1500-2000 J/kg of CAPE by the afternoon. Best
shear is currently forecast to remain just to the NW of the region,
but organized convection may find its way into NW GA as the evening
progresses that may be able to squeeze out some severe wind or hail
before becoming more disorganized.

Highs today will be in the 80s with lows overnight in the 60s across
the CWA. Tomorrow, highs will be in the 80s with even a few 90s
possible in portions of central GA.

Lusk

&&

.LONG TERM...
(Wednesday morning through next Sunday)
Issued at 251 PM EDT Mon May 6 2024

The start of the long term forecast period is quite busy as the
upper level ridging gives way to a series of disturbances rounding a
strong upper level low over the northern Plains/Great Lakes Region
through Friday. As a result, several rounds of active weather with
the potential for strong to severe storms is expected through the
end of the work week. Wednesday, a stationary boundary will be
draped to our north over the Ohio River Valley. As the first
shortwave traverses eastward over the northern Plains, a mesoscale
convective system is expected to take aim for locations north of the
I-20 corridor Wednesday afternoon into the overnight hours.
Depending on the strength of the cold pool, the line of storms may
hold on through Thursday morning. At this juncture, SPC has included
locations across our far north in a Slight Risk (Level 2 out of 5)
and locations further south to the I-20 corridor in a Marginal Risk
(Level 1 out of 5) for severe weather. With bulk shear between 40-50
KT and elevated mid level lapse rates through the overnight hours
exceeding 7 C/km, the primary hazards with these storms will be
damaging wind gusts and hail up to 1 inch. The next round of strong
to severe thunderstorms will be associated with the upper level low
progressing over the Great Lakes Region and the aforementioned
boundary sagging southward towards our forecast area. At this time,
SBCAPE is forecast to be running between 1000-2500+ J/kg, bulk shear
between 35-50 KT, and lapse rates between 6-7+ C/km through the
afternoon Thursday into Friday. For now, SPC has placed much of
north and central Georgia into a 15% probability for severe weather
Thursday through Friday morning. The primary hazards in storms would
be damaging wind gusts and 1 inch hail (though there is a chance for
hail stones to be larger should storms fire across south central
Georgia where there is a swath of higher lapse rates around the 8
C/km mark progged). While the risk for flash flooding and river
flooding is low at this time, locations across north Georgia could
see as much as 2 to 2.5" of rainfall over the next 5 days where
locally higher amounts are possible.

While the current trends signal the potential for severe weather
through the first half of the forecast period, it is important to
note that there is some uncertainty in the overall synoptic pattern
moving forward. Additionally, the severe weather threat each day may
be limited by any ongoing convection that could inhibit recovery and
destabilization. Unfortunately these systems are often notoriously
difficult to forecast this far out. We will be closely monitoring
how the forecast evolves in the coming days with respect to our
severe weather threat. Beyond Friday, we will transition into quasi-
zonal flow where drier conditions are anticipated.

KAL

&&

.AVIATION...
(18Z TAFS)
Issued at 134 PM EDT Mon May 6 2024

Convective towers with some lightning now in and around metro TAF
sites. Expect this to continue for next several hours - TEMPOs
for TSRA will likely be extended through the evening until
approximately 02Z for isolated threat. Otherwise, VFR through the
period, but one caveat: Tuesday morning has the potential for some
MVFR cigs to creep into the metro TAF sites and MCN/CSG.
Uncertainty is high on this, as evolution of ongoing storms as
well as other factors will potentially mitigate potential. Winds
will be from the SW through the period, 5-10 kts during day going
lighter at night.

//ATL Confidence...18Z Update...
Medium confidence morning cigs, high all others.

Lusk

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          64  87  68  88 /  20  10  20  30
Atlanta         66  86  69  88 /  20  10  30  40
Blairsville     60  81  64  82 /  30  20  60  60
Cartersville    64  86  66  88 /  20  20  40  50
Columbus        66  90  69  92 /  20  10  10  10
Gainesville     65  86  69  87 /  30  10  30  50
Macon           65  89  69  91 /  20   0   0  10
Rome            65  86  67  88 /  20  30  50  50
Peachtree City  65  88  68  89 /  20  10  20  30
Vidalia         67  91  69  93 /  20   0   0  10

&&

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

$$

SHORT TERM...Lusk
LONG TERM....KAL
AVIATION...Lusk