278
FXUS63 KFSD 061724
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1124 AM CST Sat Dec 6 2025

.KEY MESSAGES...

- A quick-moving winter system will bring mainly 3-7" of snow
  today.

- Snowfall rates as high as 1-1.5" inches per hour within the
  heaviest band axis during the afternoon to evening hours will
  lead to rapid accumulations. Visibility reductions and
  hazardous road conditions will lead to minor to moderate
  travel impacts at times affecting the evening commute.

- Cold wind chills will return each night through Monday with
  values as cold as 20 below possible.

- An active pattern aloft will lead to multiple precipitation
  chances through the work week. Continue to monitor the
  forecast moving forward.

&&

.UPDATE...
Issued at 847 AM CST Sat Dec 6 2025

Radar echoes continuing to expand this morning and frontal band
currently remains in it`s infancy stage. 12Z guidance continues
to confirm thoughts that as PV begins to pivot into South
Central South Dakota and Northern Nebraska, warm advection and
frontogenesis will intensify along a NW to SE axis through the
Tri-State area.

Soundings nearby the frontal band show persistent instability
sitting AOA the 700 mb layer, with MUCAPE anywhere from 10-30
J/KG residing along the MO River valley. Several of the 12Z CAMS
are picking up on this instability with simulated reflectivity
showing the convective elements feeding northeast by early
afternoon. Thus, have introduced a low end probability for
thunder along but especially south of I-90 for a few hours.

Totals generally remain on track with the previous forecast, but
have increased QPF slightly along what looks to be the favored
frontal zone. With the potential instability release, expecting
snowfall rates of 1.5" or more per hour in a handful of
counties. The increase of QPF will result in a corridor of 5 to
8" snow potential. Will extend the WSW a couple counties
westward, based on both snow amount, but also rapid worsening of
conditions this afternoon.

&&

.DISCUSSION...
Issued at 255 AM CST Sat Dec 6 2025

TODAY & TONIGHT: A dreary and cooler day ahead! Taking a look across
the area, mainly overcast skies continue this morning with most
areas sitting in the mid to upper 20s. Don`t expect much change
during the day as overcast skies and slight breezy southeasterly
winds keep temperatures locked into the 20s to low 30s with the
warmest conditions along the Missouri River Valley. Taking a
look aloft, the forecast remains on track as a quick mid-level
wave dives across portions of South Dakota, Nebraska, and
Minnesota today bringing our next chances for snow. By daybreak,
should see light returns over central SD become more widespread
across southeastern SD as increasing dPVA and mid-level frontal
forcing interact with the WAA regime ahead of the surface
trough. From here, an enhanced area of snowfall should to begin
to take shape by late morning just south of the I-90 corridor in
southeastern SD and this should be the main driver of our
accumulations going forward. As this developing band of snowfall
gradually pivots southeastwards, HREF guidance continue to show
moderate to high confidence (60%-80%) in 1" in/hr or greater
snowfall rates which should lead to moderate to heavy
accumulations at times especially across far southeastern SD,
northwestern IA, and portions of southwestern MN.

With all of this in mind and collaboration with our neighbors,
decided to upgrade portions of our Winter Weather Advisory in
northwestern IA and southwestern MN into a Winter Storm Warning
where confidence was highest in 6+ inches of accumulations. While 3-
6 inches of accumulations continues to look like the most
likely range for most areas east of the James River, can`t rule
out additional upgrades in far southeastern SD and southwestern
MN if the axis of heaviest snowfall shifts northwards or
southwards. Otherwise, should see most of the snow taper off by
late evening. Shifting gears to impacts, falling snow and rapid
accumulations will lead reductions in visibility and hazardous
travel mainly in the afternoon to evening hours. As a result,
minor to moderate travel impacts are expected especially in the
areas with the highest accumulations so be prepared to post-pone
travel plans where necessary! Looking into the rest of the
night, a fresh snowpack and lighter surface winds will lead to
much colder conditions overnight with lows being on either side
of zero. Nonetheless, wind chill will likely be even colder with
values as low as 20 below possible mainly across southwestern
MN.

SUNDAY ONWARDS: Looking ahead, a surface high will move in to
replace the departing system on Sunday. Unfortunately, so will
another mid-level wave. With this in mind, additional light
accumulations will be possible from Sunday night into Monday mainly
along and north of I-90. The cold air plunge will continue as well
with highs mainly in the single digits to low 20s. From here, the
active pattern aloft will continue for the rest of the week. By
Tuesday, a decently strong clipper wave will dive across the
northern plains bringing our next chances for precipitation.
However, increasing warm air advection (WAA) and southerly surface
winds ahead of this system will likely keep most of the
precipitation as rain or a rain/snow mix given temperatures in the
upper 30s to upper 40s. As long-range guidance starts to diverge
between Wednesday to Thursday, it looks like another clipper will
fly through the northern plains. However, there are still subtle
differences in the timing and placement of features. Lastly,
temperatures will continue to trend colder from Wednesday onwards
with highs mainly in the teens to low 20s.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1121 AM CST Sat Dec 6 2025

Moderate to heavy snow continues to move east of I-29 at mid-
day. Expecting more linear band of snow to begin to pivot and
lift north and east this afternoon, focusing in areas from Huron
to Sioux Falls and Spencer. LIFR or lower visibility expected
with ceilings dropping as low as 500 ft at times. Occasional 20
knot gusts may be possible, which could lead to brief blowing
snow by late afternoon and early evening.

Snow will slide southeast this evening, leaving MVFR ceilings. A
secondary area of light snow may drift southward out of North
Dakota into central and east central South Dakota overnight.
Visibilities may be slightly impacted in areas along Highway 14
into Sunday morning, with flurries elsewhere.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 9 PM CST this evening for SDZ040-
     055-056-069>071.
     Winter Weather Advisory until 6 PM CST this evening for SDZ038-
     039-052>054-058>060-064-065-068.
     Winter Storm Warning until 9 PM CST this evening for SDZ061-
     062-066-067.
MN...Winter Storm Warning until midnight CST tonight for MNZ089-090-
     098.
     Winter Weather Advisory until midnight CST tonight for MNZ071-
     072-080-081-097.
IA...Winter Storm Warning until midnight CST tonight for IAZ001>003-
     012>014-021-022.
     Winter Weather Advisory until midnight CST tonight for IAZ020-
     031-032.
NE...Winter Weather Advisory until 9 PM CST this evening for NEZ013-
     014.

&&

$$

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