078
FXUS62 KFFC 161845
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
245 PM EDT Thu May 16 2024



...Afternoon Area Forecast 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 tomorrow (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...
(18Z TAFS)
Issued at 127 PM EDT Thu May 16 2024

Expect the Cu field to produce FEW/SCT 030-050 cloud bases
through the afternoon. Gradually lowering CIGs will move in from
the W overnight thru tomorrow (Friday) morning. Current thinking
is that all sites except for AHN and MCN will see MVFR CIGs by
late morning as -SHRA move in, and that MVFR will persist thru
much of the day. Have introduced a PROB30 from 18z-00z tomorrow
for -TSRA at ATL, but confidence is relatively low given the
anticipated OVC mid-level cloud deck hampering destabilization.
Winds will be WNW to NNW this afternoon and will become LGT to
calm overnight. Tomorrow, winds will generally be SSE, but could
occasionally teeter over to SSW.

//ATL Confidence...18Z Update...
Medium to high confidence on all elements.

Martin


&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          62  76  65  79 /   0  70  80  90
Atlanta         66  75  68  78 /  10  80  80  90
Blairsville     58  71  61  74 /  10  80  80  90
Cartersville    62  74  65  79 /  10  80  80  90
Columbus        67  80  71  79 /  20  70  80  90
Gainesville     63  73  65  76 /   0  80  80  90
Macon           64  80  70  81 /   0  70  70  90
Rome            62  74  66  80 /  20  80  80  80
Peachtree City  63  76  67  78 /  10  80  80  90
Vidalia         67  85  72  87 /   0  30  50  90

&&

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

$$

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