291
FXUS62 KFFC 211138
AFDFFC

Area Forecast Discussion
National Weather Service Peachtree City GA
638 AM EST Tue Jan 21 2025

...New 12Z Aviation Discussion...

.SHORT TERM...
(Today through Wednesday)
Issued at 403 AM EST Tue Jan 21 2025

Main forecast concerns are timing, extent and magnitude of winter
precip today and tonight.

Monitoring new model guidance but also observed trends upstream
closely this morning, with some notable changes.

First, models and WPC have increased liquid-equivalent QPF, esp
over middle GA this afternoon. Some northward expansion of the
area of QPF > 0.01" and corresponding light snow amounts also
seen in model guidance as well. Temps have trended down just a tad
and models still struggling with how fully north Georgia will see
measurable precip and "wet-bulbing" and moistening due to
diabatic cooling from frozen precip falling into dry air.

Upstream over SE TX, much of LA and even SW MS, we are seeing
reports of snow grains or graupel, light snow and some sleet with
cloud bases as high as 5000ft and as far north as just south of
Shreveport LA. Road impacts hard to tell but if won`t take much
to get some slick spots.

Precipitation type still expected to be all snow with this event.
The only exception will be in the far southeastern corner of the
forecast area late tonight, where sleet could briefly mix in with
the snow. Freezing rain also continues to look increasingly
unlikely at any point during this event, which is in line with
forecast thermal profiles. As such, no more than a trace of ice
accumulation is forecast at this time.

With the uptick in higher amounts, the "reasonable worst case"
amounts (10% or 1/10 chance of exceedence) NBM probabilities and
recent HRRR guidance indicate 3-5 inches of snow not out of the
question for far southern parts of are area towards Cordele,
Hawkinsville and Dublin.

Based on all this, we expanded the advisory and warning a bit
further north and increased accumulations. The end time for precip
is a little faster than previous but did not lower amounts

Cold weather advisory still warranted for tonight and Wednesday
morning based on temps. Freezing of any melted snow or ice will
certainly be an issue tonight and Wednesday morning as well. Temps
wont go above freezing Wednesday until after noon to 2pm.

SNELSON/King

&&

.LONG TERM...
(Wednesday night through Monday)
Issued at 403 AM EST Tue Jan 21 2025

Another cold overnight period is expected Wednesday night into
Thursday morning, with low temperatures expected to drop into the
teen and low 20s across the forecast area. Temperatures will remain
below freezing through Thursday afternoon before rising to highs in
the upper 30s to low 40s. Snow accumulation that occurs during the
short term forecast period will likely persist given the certainty
of refreezing during the overnight and morning hours and the limited
time for melting before temperatures drop below freezing again
Thursday night. Furthermore, large portions of our forecast area
(particularly in north Georgia) will be approaching 80-90 hours
below freezing by Thursday afternoon, at which point impacts could
be seen to pipes that are not properly insulated.

Southwesterly upper level flow will return on Thursday ahead of a
longwave trough extending through the Midwest and into the Great
Plains, as the axis of this trough rotates southeastward, the
weakening Arctic high will continue to get lifted away from the
region to the northeast. This broad trough will then swing through
the Southeast on Friday and through Georgia on Friday afternoon.
However, development of a surface low associated with this trough is
expected to occur well to the east of the forecast area, off the
Atlantic coast. Also, dry air up to 850 mb is expected to further
inhibit precipitation, and PoPs remain less than 10 percent areawide.
The airmass will begin to gradually moderate over the Southeast late
Friday going into into the weekend as surface high pressure settles
in over the Southeast, with high temperatures expected to warm by
few degrees each day.  As moisture returns to the area, the next
chance for precipitation is expected to be Sunday into Monday,
though uncertainty remains with respect to timing and amounts. If
the onset of precipitation is faster, beginning early Sunday, there
is a slight chance for a light wintry mix in far northwest Georgia
before transitioning to all rain by late Sunday morning.

King

&&

.AVIATION...
(12Z TAFS)
Issued at 635 AM EST Tue Jan 21 2025

VFR conds to continue thru the TAF pd, aside from BKN to OVC MVFR
for CSG/MCN in pds of heavier SN. Chances for flurries will
increase for all sites beginning 14-15Z, with -SN (and ocnl low-
VFR to MVFR vsbys) expected by 18-20Z. Light snow showers and
flurries will then linger into the evening before tapering off by
00-02Z for northern TAF sites, 05-06Z for CSG/MCN. Approx 0.5" of
snow is forecast for KATL, but this amount is subject to change
depending on if/how early -SN breaks thru sfc dry layer and begins
accumulating. Winds will remain NNW (perhaps due N at times) at
7-12kts, with an isolated low end gusts to 20kts psbl.


//ATL Confidence...12Z Update...
Low to medium confidence snow timing/duration and associated
cigs/vsbys.
High confidence all other elements.

96

&&

.PRELIMINARY POINT TEMPS/POPS...
Athens          35  16  37  18 /  40  20   0   0
Atlanta         33  16  37  22 /  40  20   0   0
Blairsville     28   5  34  13 /  20  10   0   0
Cartersville    31  10  38  18 /  20  10   0   0
Columbus        36  16  40  19 /  70  30   0   0
Gainesville     34  15  36  19 /  30  20   0   0
Macon           37  17  39  18 /  80  60   0   0
Rome            31  12  38  18 /  10  10   0   0
Peachtree City  33  13  39  18 /  50  20   0   0
Vidalia         43  24  37  21 /  60  90   0   0

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
Cold Weather Advisory until 9 AM EST this morning for GAZ001>009-
011>016-019>025-027-030>039-041>062-066>076-078>086-089>098-
102>113.

Cold Weather Advisory from 10 PM this evening to 9 AM EST
Wednesday for GAZ001>009-011>016-019>025-027-030>039-041>062-
066>076-078>086-089>098-102>113.

Winter Weather Advisory from 10 AM this morning to 7 AM EST
Wednesday for GAZ020>025-027-030>039-041>049-052>055-057-066.

Winter Storm Warning from 10 AM this morning to 7 AM EST
Wednesday for GAZ050-051-056-058>062-067>076-078>086-089>098-
102>113.

&&

$$

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