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000
FXUS62 KFFC 091141
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
741 AM EDT Sun May 9 2021


.UPDATE...

Updated for the 12Z Aviation Discussion.

&&


.PREV DISCUSSION... /Issued 411 AM EDT Sun May 9 2021/

..Morning Area Forecast Discussion...

SHORT TERM /Today through Monday/...
As the short term period begins, a surface high is moving east away
from Georgia and towards the Atlantic coast. Southerly low level
flow is setting up behind the high, which will contribute to the
advection of warm and moist air into the area. Dewpoints will
increase from mainly the mid to upper 40s as the morning begins into
the 60s after midnight. A warmer day overall is expected in
comparison to the last couple of days, with morning lows starting
out in the 50s and increasing into the 80s across the majority of
the forecast area during the afternoon, with upper 80s forecast
across central Georgia. With a tightening pressure gradient ahead of
the next system, currently moving from the Great Plains towards the
Tennessee Valley, S to SW winds will increase to 10-15 kts with
gusts up to 25 kts across north and central Georgia this afternoon.

While increasing moisture associated with the southerly flow,
relative humidity values should remain outside of critical fire
danger thresholds. However, they could drop to between 25-30 percent
in east Georgia where the deepest mixing is expecting and where
dewpoints where be slowest to rise. In any case, the elevated winds
and dry fuels over the area could lead to the development of high
fire danger conditions, warranting a fire danger statement across
much of the forecast area, with the exception of far northwest
Georgia, where greater cloud coverage is anticipated during the
afternoon.

The upper level shortwave and an associated surface low will be
passing eastward through the Tennessee Valley region towards the mid-
Atlantic Coast tonight into Monday morning. Hi-res guidance
continues to indicate a line of showers and thunderstorms entering
northwest Georgia this evening ahead of a cold front extending from
the surface low. Guidance also indicates this line will be most
organized as it enters the forecast area before steadily weakening
as it pushes to the south and east. While persistent upper level
flow will impede upper level support for storms ahead of the front,
30-40 kt winds at the 850 mb level will contribute to enhanced deep
layer shear. MUCAPE values are moreover anticipated to range from
500-1000 J/kg during the overnight hours. The combination of these
factors will contribute to the potential for strong and gusty winds
in far northwest Georgia as the line enters the area. The threat for
severe thunderstorms will progressively diminish overnight as
showers and storms spread south and east. Locally heavy rainfall is
also possible when the line of storms is at its strongest entering
the far northwest.

Likely PoPs are forecast across much of north and central Georgia by
Monday afternoon as the cold front continues to push southeastward
through the area. MUCAPE values of 1000-1500 J/kg will be sufficient
to support at least scattered thunderstorms during the daytime
Monday, with the best coverage anticipated during the afternoon
hours when peak daytime heating occurs. Dynamics near the front will
be pretty unimpressive. However, considering the deep moisture in
place, combined with enhanced deep layer bulk shear and modestly
steepened mid-level lapse rates of 6.5-7.0 J/kg, there is a chance
that some isolated storms could become strong to severe on Monday
afternoon.

King

LONG TERM /Monday Night through Saturday/...
No major forecast concerns in the long term period. Zonal flow
pattern in place through Thursday night after which 00Z model
guidance generally develops broad troughing over the eastern CONUS
through next weekend, though there is some minor divergence in
forecast solutions after Friday. Not seeing any evidence of
strong/severe convection or heavy rain at this time.

Zonal flow pattern often associated with increased forecast
uncertainty as it is difficult to pick out often subtle upper level
speed maxima to trigger further wave and cyclone development.
Forecast PoPs through Thurs reflect this uncertainty with generally
Chc category SHRA/TSRA, with highest values over middle GA as warm
advection and moisture plume streaming from the WSW most pronounced
in that area.

By Friday, wave developing in eastern CONUS trough moves east of us
with subsidence but strong signal in 00Z guidance of an upstream
wave in NW flow that should bring at least thick clouds on Saturday.
For now, no evidence of measurable precip on Saturday but with
uncertainty that far out, would not be surprised if PoPs trend back
up some in later forecasts.

SNELSON

FIRE WEATHER...
High fire danger conditions are anticipated this afternoon across
much of north and central Georgia, warranting a fire danger
statement to the east of a line from Carrollton to Chatsworth. Dry
fuels remain across the forecast area and southwesterly winds are
forecast between 10-15 mph and gusts as high as 25 mph. Relative
humidity values are moreover expected to decrease to near 25 percent
in east-central Georgia this afternoon.

King

&&

.AVIATION...
12Z Update...
VFR conditions are expected through the period, with mainly mid to
upper level clouds in place over the area today. A cu field
around 5 kft is anticipated during the afternoon hours. Cloud
coverage is expected to increase during the overnight hours and
gradually lower, reaching MVFR by 09-10Z at the metro ATL sites.
SHRA/TSRA is expected to approach ATL overnight and into early
Monday morning. Hi-res guidance remains inconsistent with timing
and coverage. VCSH has been added starting at 05Z with a PROB30
for SHRA after 12Z Monday. Light SW winds will quickly increase
this morning to 10-13 kts with gusts up to 22 kts during the
afternoon hours before diminishing overnight.

//ATL Confidence...12Z Update...
Medium confidence on timing of precipitation and lowering
ceilings.
High confidence on all other elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          84  64  79  58 /   5  30  60  30
Atlanta         83  64  77  59 /   5  50  70  30
Blairsville     78  59  70  51 /  20  60  70  20
Cartersville    83  62  74  53 /  10  60  60  30
Columbus        88  65  78  63 /   5  40  80  40
Gainesville     82  63  76  57 /   5  50  60  30
Macon           89  65  81  63 /   5  20  60  30
Rome            83  63  74  54 /  20  60  60  20
Peachtree City  85  64  78  58 /   5  40  70  30
Vidalia         90  66  85  66 /   0   5  50  30

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...King
LONG TERM....SNELSON
AVIATION...King