318
FXUS63 KFSD 082352
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
552 PM CST Mon Dec 8 2025

.KEY MESSAGES...

- Fog and low level stratus remains along and east of I-29 this
  afternoon. A Dense Fog Advisory remains in effect until 10 pm
  this evening. Slick spots are possible on roads and untreated
  surfaces.

- Confidence remains high in strong winds impacting the area for
  Tuesday through Wednesday morning. A Winter Storm Watch for
  Blizzard conditions has been issued for the vast majority of
  the area. A High Wind Warning has been issued for Gregory,
  Charles Mix, and Brule counties. Winds up to 50 to 60 mph is
  expected in both headlines. Blowing snow will be the main
  impact where visibilities down to a quarter of a mile is
  possible.

- Chances for snow will persist throughout the week and into the
  weekend. At this time, snowfall amounts look to be light with
  each chance.

- Much colder temperatures are expected from the middle of the
  week through the weekend. Cold Weather headlines may be
  needed.

&&

.DISCUSSION...
Issued at 318 PM CST Mon Dec 8 2025

Low level stratus and fog persists across the area this afternoon.
The fog is being driven by weak southerly moisture advection,
keeping the boundary layer saturated. The stratus and fog have begun
to nudge eastwards as low level winds begin to take on a more
westerly component thanks to an advancing warm front. Thus, have
left the Dense Fog Advisory in effect through 10 pm for locations
along and east of I-29. Trends will be monitored through the rest of
today to see if any further reductions are needed in the Advisories
extent. Tonight will be quiet with low temperatures falling to the
20s to up to about 30F.

Things begin to change on Tuesday as a strong upper level shortwave
trough pushes through the Northern Plains. This will bring a round
of precipitation to the area beginning Tuesday morning. Precipitation
looks to begin as light freezing rain before transitioning to plain
rain as temperatures warm through the morning hours, thanks to
persistent warm air advection (WAA) aloft. A few places might see a
light glaze of ice for a brief period of time during the morning and
early afternoon hours before plain rain melts away the ice. The
afternoon will still see some cooler temperatures across the area
thanks to persistent cloud cover and current snowpack across the
majority of the area. Have highs only warming to the mid 30s east of
the James River up to the 40s and 50s west of the River. The bulk of
the rain will push east of the area by the late afternoon hours. The
other component to Tuesday will be strengthening winds during the
afternoon hours as a strong cold front will pushes through the area.
A strong shot of cold air advection (CAA) is expected with the
passing front, resulting in very strong winds across the entire
area. The strongest winds will come during the evening and overnight
hours where gusts up to 50 to 60 mph is likely (>=70% chance). These
strong winds will be capable of blowing the current snow pack around
which can result in blowing snow across most of the area. The main
uncertainty regarding the extent of the blowing snow is due to the
previously mentioned rain and temperatures warming above freezing.
The rain and warmer temperatures will likely melt some of the snow
pack. Even with the quickly falling temperatures behind the front,
questions remain how blowable the snowpack will be. As such, have
issued a Winter Storm Watch for Blizzard Conditions from noon on
Tuesday through noon Wednesday. A High Wind Warning has been issued
for Gregory, Charles Mix, and Brule counties due to these counties
having a much lower snowpack to non existent snowpack. The High Wind
Warning is in effect from noon Tuesday through 3 am Wednesday.

Winds will be weakening during the morning hours on Wednesday as
high pressure slides through the Northern Plains. Tuesday will be
the last "warm" day across the area before a much colder airmass
settles into place for the rest of the week. Highs will be below
average in the 20s to down to the teens and single digits come
Friday through the weekend. With such cold temperatures in place
along with light winds in place, Cold Weather headlines may be
needed. Highs may trend back towards seasonable come early next
week.

For precipitation chances, there looks to be persistent chances for
snow throughout the week. Currently, the highest chances (30-40%)
for snow looks to come on Thursday. Though additional chances will
persist through the weekend. Given how these are all clipper
systems, light snowfall is most probable with each passing clipper
at this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 551 PM CST Mon Dec 8 2025

Low stratus and patchy dense fog covers much of the region from the
I-29 corridor and east. Here IFR to LIFR ceilings will continue for
the next few hours before relatively warmer and drier air pushes in
from the west clearing stratus and fog.

Around mid-morning a storm system will move into the area from the
northwest. For areas along and north of Highway 14 precipitation
should begin as a wintry mix including freezing rain or drizzle. Ice
accumulation, if any, is expected to be a light glaze to a hundredth
of an inch. As the storm sinks further southeast precipitation will
increase in coverage and transition over to all rain. By the early
evening most of the rain will be located over southwest Minnesota
and northwest Iowa. It will linger here for a few hours and will
likely transition to snow before exiting after midnight.

Lightly breezy southerly winds Tuesday morning will become westerly
then northwesterly as a strong cold front (associated with the
previously mentioned storm) passes through the region. Winds will
increase drastically over a short period of time. Gusts of 35-45 kts
are expected west of the James River by early afternoon. Winds
continue to increase as they progress east. By the end of the
period, gusts of 40-50 kts are expected region wide. Strong winds
continue into Wednesday. Some reductions in visibility due to
blowing and drifting snow are likely. In addition, some LLWS is
possible toward the end of the period, but confidence was too low to
include at this time.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 10 PM CST this evening for SDZ040-055-
     056-062.
     Winter Storm Watch from Tuesday evening through Wednesday
     morning for SDZ067-070-071.
     Winter Storm Watch from Tuesday afternoon through Wednesday
     morning for SDZ038>040-052>056-058>062-064>066-068-069.
     High Wind Warning from noon Tuesday to 3 AM CST Wednesday for
     SDZ050-057-063.
MN...Dense Fog Advisory until 10 PM CST this evening for MNZ071-080-
     081-089-090-097-098.
     Winter Storm Watch from Tuesday evening through Wednesday
     morning for MNZ080-081-089-090-098.
     Winter Storm Watch from Tuesday afternoon through Wednesday
     morning for MNZ071-072-097.
IA...Dense Fog Advisory until 10 PM CST this evening for IAZ001>003-
     012>014-020>022-032.
     Winter Storm Watch from Tuesday evening through Wednesday
     morning for IAZ001>003-012>014-020>022-031-032.
NE...Winter Storm Watch from Tuesday evening through Wednesday
     morning for NEZ013-014.

&&

$$

DISCUSSION...Meyers
AVIATION...AJP