101
FXUS63 KFSD 081657
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1057 AM CST Wed Jan 8 2025

.KEY MESSAGES...

- Moderating temperatures for today and Thursday.

- A round of snow is expected on Thursday. There will be a
  60-80% probability for an inch of snow through the Highway
  corridor, with lesser amounts to the south.

- A second round of light snow is possible over the weekend,
  with 70-80% probabilities of amounts remaining below an inch.

- Temperatures fall back to below normal levels for the
  beginning of next week.

&&

.DISCUSSION...
Issued at 350 AM CST Wed Jan 8 2025

A narrow band of stratus has developed over portions of south
central SD overnight. With the very cold temperatures in place across
the area, the clouds have been able to squeeze out occasional
flurries. Latest hi-res guidance would indicate this stratus breaking
up during the early morning hours.

Otherwise, we will begin to see a slight moderation in temperatures
today - this in response to warm air advection as the surface high
presently centered over our area shifts eastward while winds aloft
take on a more west/southwesterly direction. With that, 925 mb
temperatures will rise to 0 to -9 C across the area, and this will
yield highs in the lower 20s east of Interstate 29 to around 30 over
south central SD.

For tonight and Thursday, models are in good agreement on an upper
level shortwave and surface trough tracking through the region by
later tonight into Thursday. With increasing lift and saturation
with in the DGZ, light snow is expected to develop through central
SD after midnight tonight, then pushing across our area on Thursday
into Thursday evening. A couple of the hi-res models would produce
freezing rain in some locations at the onset of precipitation late
tonight with a shallow layer of warmer air aloft, but soundings
indicate that wet bulbing would result in any precipitation quickly
turning to snow. In any event, snowfall looks to be light with a
current forecast of around an inch through the Highway 14 corridor,
to a half an inch or less to the south of there. This is supported
well by the latest HREF ensembles which show a 60-80% probability of
greater than a half an inch through the Highway 14 corridor. With
continuing warm air advection out ahead of the aforementioned
features, highs for Thursday will be even milder - in the lower to
mid 30s. In response to cold air advection and an increasing SPG
behind the aforementioned surface trough, northwesterly winds will
pick up in the afternoon, gusting 25 to 35 mph in the afternoon -
strongest in the west. This could result in a bit of blowing snow in
areas that have a snowpack - though the somewhat milder temperatures
may keep this at bay.

Behind this system, an upper level trough swings through the region
on Friday. With cooler air feeding in behind Thursday`s frontal
passage, temperatures will fall back a bit with highs back into the
20s. No precipitation is expected during the day.

The next system to affect our area will come in on Saturday into
early Sunday as another shortwave/clipper system drops into the
Northern Plains. This will bring the potential for another round of
light snow across the area during that period. Snowfall again looks
to be on the lighter side - most likely an inch or less - with
current ensembles showing only a 20-30% probability of receiving
greater than an inch. Temperatures on Saturday look close to
seasonal averages (mid to upper 20s). Behind the system, much colder
air will sweep into the region on Sunday, with highs falling back to
the teens to lower 20s.

A broad upper level trough will develop over the CONUS for the
beginning of next week, holding our temperatures to below normal
levels. Little if any precipitation is expected through the period.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1053 AM CST Wed Jan 8 2025

VFR this afternoon and much of tonight. Light snow will
overspread the area late tonight into Thursday, beginning
earliest in central SD, then likely weakening/dissipating a bit
and shifting into areas east of I-29 late afternoon into the
evening. Outside of the snowfall will be increasing northwest
winds on Thursday with gusts around 40 mph possible. The
strongest winds will be west of I-29 before sunset and near and
east after sunset. If enough snow falls there will be reductions
in visibility at times with the stronger wind gusts, especially
in areas with existing snow cover that can get closer to an inch
of new snow. MVFR and possible IFR conditions expected tomorrow
with the snow.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...JM
AVIATION...08