101
FXUS62 KFFC 170607
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
207 AM EDT Fri May 17 2024


...New 06Z Aviation Discussion...

.SHORT TERM...
(This afternoon through Friday)
Issued at 237 PM EDT Thu May 16 2024

A transient upper-level ridge and associated surface high pressure
are producing dry, warm, mostly sunny conditions this afternoon.
Temperatures are on track to top out in the mid-80s to upper 80s
outside of the mountains.

Scattered to widespread showers are expected to move in from west to
east Friday morning as a shortwave trough and associated upper-
level speed max approach from the west. Showers and ample cloud cover
in the morning and afternoon will likely preclude deep convection
during the day, but depending on the progression of convective
clusters/an MCS upstream over MS and AL, portions of the CWA could
have convection to contend with overnight. SREF has a 25% to 45%
chance of Supercell Composite Parameter (SCP) greater than 5 across
much of the CWA from 00z to 06z Saturday, which indicates the co-
location of ample shear and ample instability. The primary hazard
will be damaging wind gusts with secondary, less-probable hazards of
large hail (1" in diameter or larger) and tornadoes. At this time,
SPC has much of central GA outlooked in a marginal risk with the far
southwestern portion of the CWA (including Columbus and Americus) in
a slight risk. All this said, the severe weather potential is
conditional, as an equally reasonable scenario is that showers during
the day tomorrow will stabilize the environment and produce a cold
pool, which could encourage upstream convection over MS and AL to
weaken and/or migrate southeastward along the cold pool boundary. The
CAMs are all over the place in their handling of precip Friday into
Saturday.

In addition to the conditional threat for severe weather, WPC has an
area encompassing western GA and the Atlanta metro outlooked in a
Slight Risk for excessive rainfall. The current expectation is that
the potential for heavy rain will peak during the afternoon and
evening hours on Friday as the chance for deep convection and/or
training increases while PWAT is progged to reach 1.5" to 1.8".
Additionally, soils across much of the area under the slight risk
are quite saturated from recent rainfall, which could set the stage
for increased runoff. The potential for heavy rain will carry over
into the start of long term period, so the forecasted rainfall totals
are covered in said discussion below.

Martin

&&

.LONG TERM...
(Saturday morning through next Wednesday)
Issued at 237 PM EDT Thu May 16 2024

Looking into the longterm forecast, specifically Saturday,
conditions will be heavily dependent on short term outcomes with the
MCS path and subsequent destabilization potential. Continued shear
and lifting support along the warm front, and with the slowly
approaching shortwave, will mean that any CAPE that does develop will
be readily accessed. We will need to watch closely for a continued
severe threat of damaging winds and hail, although a brief tornado
may not be out of the question. Should we get cut off from the warm
and moist air to the south, conditions will likely behave for the
most part. In either scenario, flooding may become a concern given
the potential deep moisture (PWATs>1.8") and storm motion/flow
parallel to the front through Saturday evening. Current model
guidance already indicates vorticity streamers along the front which
drive efficient precipitation training over small areas. While the
heaviest rains should stick over AL, highly localized values of 4+"
(Friday through Saturday afternoon) are possible. Precipitation
outside of concentrated thunderstorm training will likely see closer
to 2 to 3 inches. Should GA become cutoff from the warm and moist
flow, the potential for localized values of 4+" will be greatly
diminished but not outright removed.

Conditions begin to dry out Sunday with a few remnant showers
lingering on the backside of the low. As the low moves offshore, NE
flow begins to dominate and drier air starts to move in. Models
continue to indicate some minor cyclogenesis with the low as it moves
off the East Coast. This will reinforce NE flow and set much of
North and East Central GA in a pseudo wedge pattern on Monday. Cloudy
conditions and a few sprinkles may be possible with this through mid
next week. The main effect will be felt with the temperatures which
have continued in a downward trend over the last several model runs.
Model uncertainty remains elevated with this scenario (with a model
spread of ~15 degrees for some areas), so will likely continue a
blend of the previous forecast temperatures with continued drop in
Monday`s highs. Temperatures through mid next week will continue to
warm, sending highs into the mid 80s and near 90. Small precipitation
chances return for mostly north GA on Wednesday and into Thursday
morning.

SM

&&

.AVIATION...
(06Z TAFS)
Issued at 206 AM EDT Fri May 17 2024

High clouds will continue to spread from west to east across the
forecast area over the next few hours. Ceilings will gradually lower
through the morning hours, down to 8-10 kft by 10-12Z and further to
MVFR by 15Z. Showers are forecast to spread into the area this
morning, with scattered showers moving into ATL by 12Z and becoming
more widespread around by 15Z. Chances for thunderstorms appear to
be greatest this afternoon with forcing from a disturbance aloft
combined with diurnal instability. As such, a PROB30 for TSRA has
been maintained from 18-00Z at all sites. Winds will be light, at 4
kts or less, and variable to start the period, coming up from E to
SE at 4-8 kts after sunrise. Winds may briefly shift to SW this
afternoon in portions of central Georgia. Ceilings are forecast to
lower to IFR after 00Z at the northern TAF sites.

//ATL Confidence...06Z Update...
Medium confidence on the timing of ceiling lowering and precip
onset.
High confidence on all other elements.

King

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          65  79  63  81 /  80  90  50  60
Atlanta         68  78  65  81 /  80  90  50  40
Blairsville     61  74  59  76 /  80  90  50  60
Cartersville    65  79  62  81 /  80  90  50  40
Columbus        71  79  66  84 /  80  90  50  30
Gainesville     65  76  64  80 /  80  90  50  60
Macon           70  81  66  84 /  70  90  50  50
Rome            66  80  62  84 /  80  80  50  40
Peachtree City  67  78  64  82 /  80  90  50  40
Vidalia         72  87  69  84 /  50  90  70  60

&&

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

$$

SHORT TERM...Martin
LONG TERM....SM
AVIATION...King