776
FXUS63 KFSD 082119
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
319 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 /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1134 AM CST Mon Dec 8 2025

Latest satellite imagery shows low level stratus and fog across the
majority of the area. Ceilings and visibilities range through the
entire set of flight categories from VFR to LIFR. VFR conditions are
present across parts of south central South Dakota with all other
lower categories along and north of I-90 and the entirety of
northwest Iowa. With weak southerly low level winds in place, think
the fog and stratus will persist through the rest of the daylight
hours. Winds then begin to take on a westerly component late this
afternoon and evening. Think that the fog and stratus will begin to
push eastwards and clear all TAF terminals and the entire area as
this westerly component kicks in.

Winds will turn back to out of the south/southwest by tomorrow
morning. The next chance for precipitation looks to return to the
area by the end of the TAF period. This looks to be generally along
and north of highway-14. Precipitation will be in the form of light
freezing rain before transitioning to plain rain. Low level wind
shear (LLWS) is also possible to end the period as well by KHON.

&&

.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...Meyers