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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KFFC 171044
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
644 AM EDT Wed Apr 17 2024



...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Thursday)
Issued at 342 AM EDT Wed Apr 17 2024

As the morning begins, the 500 mb ridge over the Southeast continues
to move eastward towards the Atlantic coast. Upper level flow across
the region will become more zonal on the back side of the ridge.
Meanwhile, a closed and vertically stacked low pressure system over
the Midwest continues to track northeastward towards the Great Lakes
region. A cold front extending from the low will advance towards
north Georgia today, advancing into the Tennessee Valley region by
this afternoon. Upper level clouds continue to stream across the
area, and will thicken and lower as the front moves closer to the
area. Low temperatures will start the morning primarily in the low
60s, and high temperatures this afternoon will range from the upper
70s in far north Georgia (where cloud cover will be the thickest) to
the mid 80s in central Georgia. With continued warm air advection
from the southerly low-level flow, dewpoints are forecast to be in
the 50s across the area today. As a result, relative humidity values
are forecast to range from 30-40 percent across the majority of the
area, which should inhibit fire danger concerns in spite of dry 10-
hour fuels.

An outflow ahead of the front is expected to advance into northwest
Georgia by mid-afternoon. Hi-res guidance continues to indicate a
broken line of showers and thunderstorms ahead of this outflow
boundary. Warm, humid conditions will contribute to SBCAPE values of
800-1200 J/kg during peak heating hours this afternoon. 0-6 km bulk
shear values are furthermore progged to range from 40-50 kts while
mid-level lapse rates steepen up to 7 C/km. The combination of these
factors indicates that isolated storms within this line will have
the potential to become strong to severe, capable of producing
damaging wind gusts and hail up to 1 inch. Precipitable water values
are furthermore likely to increase to over 1.5" immediately ahead of
the outflow. While, the outflow/storms should have quick southward
progression, stronger storms could produce locally heavy rainfall.
The boundary will then continue into central portions of the state
this evening into tonight, at which point it is anticipated
dissipate and precipitation will diminish in coverage.

On Thursday, a weak upper ridge will move across the east-central
CONUS. The subsidence under this ridge will inhibit rain chances
through much of the daytime on Thursday and diminish cloud coverage,
even though there will be little change to the airmass over the
region. Low temperatures on Thursday morning will start out in the
low 60s once again. With plenty of sunshine, high temperatures are
forecast to be warmer than today, reaching into the mid 80s in north
Georgia and upper 80s in central Georgia. As the ridge quickly moves
away to the east on Thursday afternoon, a shortwave traversing the
upper level flow will move through the Ozarks region. Showers and
thunderstorms ahead of this feature will begin to approach the
forecast area from the west as the long term period begins.

King

&&

.LONG TERM...
(Thursday night through Tuesday)
Issued at 342 AM EDT Wed Apr 17 2024

4/17 LONG TERM

At a glance:

    - Low-end chance of a strong to severe storm Friday afternoon

    - Very warm until frontal passage Sunday

As we enter the extended on Friday, flow has become quasi-zonal at
the mid-levels. The eastward movement of a closed low/associated
trough rotating across central Canada will send several shortwaves
(and accompanying pulses of moisture) across the Southeast Friday
through Sunday, culminating in a full cold-frontal passage. As a
result, slight chance to chance PoPs will linger across a majority
of the forecast area through the weekend. A Marginal (1/5) Risk for
severe weather is in effect for the northern half of the state on
Friday. Meager (~1000 J/kg) surface-based CAPE and ~30-40kts of bulk
shear will support the development of a few strong to severe storms
during the afternoon, capable of producing isolated large hail or
damaging wind gusts. Not expecting big things as far as
precipitation totals, and the multi-day total rainfall through the
weekend currently looks to be between 0.25 and 0.8".

From Monday on, high pressure moves back in at the surface, and the
mid-levels trend toward a more tranquil pattern. For now, it looks
like a dry start to the work week.

Highs will be quite warm through Saturday -- in the 80s areawide
-- which is as much as 8-14 degrees above average for late April.
Lows will be comparatively warm, in the upper 50s to 60s. In the
wake of the front on Sunday and Monday, expect a return to more
seasonable (trending toward unseasonably cool) temperatures: highs
in the 60s to lower-70s, and lows in the upper-40s to 50s.

96

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 634 AM EDT Wed Apr 17 2024

Upper level clouds will persist across north and portions of
central Georgia through much of the day, and will gradually lower
this afternoon. VFR ceilings around 060-070 are anticipated by 21Z
ahead of a line of precip approaching from the north. -SHRA is
anticipated from 23-04Z at the ATL sites as the showers advance
through the area. Isolated thunderstorms will be possible, but at
this time, confidence remains too low to warrant mention of
thunder in the TAFs. Winds will be nearly due S at 3-6 kts in the
early morning, shifting to SW after sunrise. Winds will increase
through the early afternoon until peaking at 9-12 kts with gusts
of 18-22 kts in the mid to late afternoon. Winds will shift to W
and diminish to 3-6 kts tonight into the early Thursday morning.
MVFR clouds will be possible in the early morning hours on
Thursday after 09-10Z.

//ATL Confidence...12Z Update...
Medium confidence on all elements.

King
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Athens          60  88  63  85 /  30  10  20  40
Atlanta         62  86  65  82 /  50  10  30  50
Blairsville     55  83  58  77 /  20  10  40  70
Cartersville    59  86  62  81 /  50  10  40  60
Columbus        64  87  65  87 /  10  10  10  30
Gainesville     60  86  63  81 /  30  10  30  50
Macon           64  87  65  88 /  10  10  10  30
Rome            60  86  63  81 /  30  20  50  60
Peachtree City  61  87  64  84 /  40  10  20  50
Vidalia         65  88  66  89 /  10  10   0  20
-- End Changed Discussion --

&&

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

$$

SHORT TERM...King
LONG TERM....96
AVIATION...King