079
FXUS63 KFSD 091829
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1229 PM CST Tue Dec 9 2025

.KEY MESSAGES...

- A winter system will bring periods of rain, wintry mix, light
  snow, and strong winds to the region today. Strong
  northwesterly winds with gusts between 45-60+ mph could blow
  and/or drift our existing snowpack created near-whiteout to
  whiteout conditions at times this evening and overnight.
  However, some uncertainty remains.

- A busy week will continue with a risk of precipitation nearly
  every 1.5 days. Most of the precipitation events will remain
  light, but the systems on Thursday and Saturday will bear
  watching.

- Confidence is also moderate to high (50%-70%) that arctic air
  will bring near advisory level wind chills to the region by
  next weekend.

&&

.UPDATE...
Issued at 1228 PM CST Tue Dec 9 2025

A strong upper level low is poised to impact the area this evening,
through the overnight hours, and into tomorrow morning. The biggest
impact with this system continues to be the wind. Confidence remains
high a strong cold front pushing through the area this afternoon and
evening, delivering a strong shot of cold advection in its wake.
This shot of cold air advection (CAA) will quickly ramp up northwest
winds with gusts increasing up to 50-60 mph. Isolated higher gusts
exceeding 60 mph is possible as well. The strongest gusts will come
this evening and persist into the overnight hours before beginning
to weaken into the early morning hours. Patchy blowing and drifting
snow is expected across the vast majority of the area due to the
current snowpack in place, resulting in reduced visibility.

Latest hi-resolution guidance continues to show that a second shot
of CAA tonight will steepen low level lapse rates enough to generate
just a hint of instability. This will allow some snow showers to
develop across mainly southwest Minnesota and into adjacent portions
of southeast South Dakota and northwest Iowa. These snow showers may
mix down slightly stronger winds and result in visibilities down a
quarter mile or less in falling snow.

In terms of headlines, have transitioned the Winter Storm Watch to a
High Wind Warning for the entire forecast area. Have also issued a
Winter Weather Advisory for all of southwest Minnesota and parts of
southeast South Dakota and northwest Iowa. Confidence is not high
enough in Blizzard conditions being met given how the current rain
and warm temperatures will modify the current snow pack. Will
continue to closely watch trends through the evening and overnight
hours.

&&

.DISCUSSION...
Issued at 340 AM CST Tue Dec 9 2025

TODAY & TONIGHT: An active day ahead! Taking a look across the area,
high clouds continue to stream into the area with another push of
increasing mid-level warm air advection (WAA) this morning. Between
this and southerly to southwesterly surface winds, this will create
favorable conditions for more milder temperatures today with highs
closer to the upper 30s to mid 40s for most areas and 50s across
southcentral SD. With this, our focus shifts northwards as a quick
moving clipper progresses through the upper plains bringing our next
precipitation chances (50%-70%). With soundings continue to show a
warm nose of +4 to +7 degrees C between 800:900mb, most of the
precipitation will likely start as a wintry mix of freezing rain and
rain initially along and north of I-90 this morning. While this
could lead to a light glaze of ice mainly along and north of the
U.S. Highway-14 corridor, diurnal heating into the early afternoon
should allow things to transition to mainly rain through the early
evening. Now on to the main concern which are the stronger winds.

A tightening SPG and strong push of cold air advection (CAA) with a
cold front will likely lead to increasing winds speeds from this
afternoon into the overnight hours with the strongest winds likely
occurring overnight. Current thoughts are wind gusts between
45-55 mph are expected with pockets of up to 60+ mph possible
mainly across our higher elevation areas. With this in mind, the
blowing and drifting of our remaining snowpack is expected but
to what degree continues to be the plaguing question. Most of
the uncertainty revolves around how the rain and mild temperatures
mentioned above affect the blowable nature of the snow and if a
crust forms to keep most of it in place. While there`s an argument
for both sides the uncertainty with this was enough to keep our
Winter Storm Watch in place for now after collaborating with
neighboring offices this morning. Nonetheless, be prepared for
rapid reductions in visibility on the evening commute as surface
winds continue to strengthen. Lastly, as temperatures continue
to fall overnight, could see some additional snow showers swing
through portions of southwestern MN around midnight (06z).
However, accumulations will likely only amount to a dusting
(<1") if any.

Looking into the rest of the week, Additional chances for snow
return on Thursday and Saturday. However, locational differences
between mid to long-range guidance continues to lead to uncertainty.
Nonetheless mostly light accumulations are expected. Heading
into the weekend, arctic air will filter into the region leading
to colder temperatures and even colder wind chills. With this
in mind, advisory level wind chills aren`t out of the question
especially across southwestern MN by Sunday morning. This
sentiment is agree upon in the ensembles with most members
showing 50%-70% probabilities of wind chills at or less than -25
degree across areas northeast of a Huron to Beresford to Ida
Grove, IA line.,

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1118 AM CST Tue Dec 9 2025

Light rain will continue to move southeast through the CWA early
this afternoon. We`ll continue to watch the progression of a
strong frontal boundary moving southeast later this afternoon,
which will begin bringing 40+ knots gusts into early evening and
falling temperatures.

The arrival of a secondary cold front late this evening will
lead to even higher surges of wind over 50 knots, along with
widespread MVFR to IFR ceilings. Big questions remain on the
potential for blowing snow and then the development of
horizontal convective rolls after midnight. Should the snowpack
be able to be lofted, it will reduce visibilities quickly. For
now, will suggest a persistent MVFR visibility with a lower
probabilities of 1 mile or lower visibility based on HREF
guidance through the core of the peak winds. These will need to
be monitored and amended as needed over the upcoming 18 hours.

Ceilings will gradually improve and winds will weaken Wednesday
morning.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday
     for SDZ040-055-056-062-066-067-069>071.
     Winter Storm Watch Wednesday morning for SDZ038>040-052>056-
     058>062-064>071.
     Winter Weather Advisory from 9 PM this evening to 4 AM CST
     Wednesday for SDZ040-056.
     Winter Storm Watch until 6 PM CST this evening for SDZ038>040-
     052>056-058>062-064>066-068-069.
     High Wind Warning from 6 PM this evening to 3 AM CST Wednesday
     for SDZ038-039-052>054-058>061-064-065-068.
     High Wind Warning until 3 AM CST Wednesday for SDZ050-057-063.
MN...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday
     for MNZ071-097-098.
     Winter Storm Watch Wednesday morning for MNZ071-072-080-081-
     089-090-097-098.
     High Wind Warning from 9 PM this evening to 6 AM CST Wednesday
     for MNZ072-080-081-089-090.
     Winter Weather Advisory from 9 PM this evening to 4 AM CST
     Wednesday for MNZ071-072-080-081-089-090-097-098.
     Winter Storm Watch until 6 PM CST this evening for MNZ071-072-
     097.
IA...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday
     for IAZ001-012-020-031.
     Winter Storm Watch Wednesday morning for IAZ001>003-012>014-
     020>022-031-032.
     High Wind Warning from 9 PM this evening to 6 AM CST Wednesday
     for IAZ002-003-013-014-021-022-032.
     Winter Weather Advisory from 9 PM this evening to 4 AM CST
     Wednesday for IAZ002-003-014.
NE...High Wind Warning from 8 PM this evening to 6 AM CST Wednesday
     for NEZ013-014.
     Winter Storm Watch Wednesday morning for NEZ013-014.

&&

$$

UPDATE...Meyers
DISCUSSION...05
AVIATION...Dux