404
FXUS63 KFSD 270955
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
355 AM CST Thu Nov 27 2025

.KEY MESSAGES...

- A dry and chilly Thanksgiving is expected, with highs ranging
  from the mid-20s where there is a snowpack to the mid-30s
  along the Missouri River Valley.

- Our next storm system remains on track for Friday through
  Saturday, with a slight southward shift in the heaviest
  snowfall projections. With a potential for moderate to
  briefly heavy snowfall rates across portions of southeast
  South Dakota and Siouxland with the initial snow band Friday
  afternoon/night, the Winter Storm Watch has been expanded to
  cover most of our forecast area for Friday afternoon through
  Saturday evening.

- This system will cause disruptions to post-Thanksgiving Day
  travel, so be sure to keep up to date with the latest forecast
  and be prepared to adjust your travel plans.

- It turns much colder at the start of next week, with the
  potential for lows below zero degrees Sunday night/Monday
  morning.

&&

.DISCUSSION...
Issued at 355 AM CST Thu Nov 27 2025

THANKSGIVING DAY: A quiet day for those traveling today with
partly to mostly cloudy skies and relatively light winds. Low
clouds drifting south into northern parts of the forecast area
may persist much of the day and combined with recent snowpack,
will hold high temperatures in the mid to even lower 20s north
of the I-90 corridor. Mid-level clouds currently sliding across
our southwest counties are expected to see more thinning, with
more afternoon sun over snow-free ground which should allow for
highs in the mid 30s through the Missouri River Valley.

FRIDAY-SATURDAY NIGHT: Main focus for the post-holiday period
remains on a strengthening storm system which will impact a
large portion of the northern Plains-Upper Midwest. The event
will begin for the local area with expansion/development of a
narrow band of snow west of I-29 by midday Friday in response to
increasing warm advection/mid-level frontogenesis beneath the
right entrance region of a 100+ kt upper jet. Model soundings
also indicate a neutrally stable to slightly unstable layer
above the frontal surface, which could aid in narrowing the snow
band with a potential for briefly heavy snowfall rates by Friday
afternoon and evening. This currently appears to be focused from
northwest to southeast across southeast South Dakota into the
Sioux City area. HREF localized probability matched mean (LPMM)
QPF for just Friday afternoon shows bands of 0.10 to 0.25" of
liquid with isolated higher pockets, which could translate to a
quick 1 to 3 inches of snow by Friday evening.

This band would then pivot northeastward through Friday evening,
with forcing for the snowband gradually weakening overnight as
the lead jet exits east and mid-level front begins to weaken.
Energy will become refocused across eastern Nebraska and Iowa
later Friday night through Saturday as the mid-upper trough
digs southeast into Iowa, becoming slightly negatively tilted
as a stronger upper jet digs into the base of the trough through
the central Plains. A broad area of light snow will continue
across much of southeast South Dakota and southwest Minnesota
during this time as the inverted trough slides through the area.
However, the greater potential for heavier rates has shifted a
bit south, still clipping areas along and east of the IA/MN
Highway 60 corridor with 70-90% probabilities of exceeding 6
inches of snow, and 40-70% probabilities of exceeding 8 inches.

Although probability of greater than 6 inches is lower across
southeast South Dakota/Siouxland (30-60% along and east of the
James River Valley), the potential for a heavier burst Friday
afternoon/evening is concerning given Friday is the start of the
post-holiday travel period. Add in that light snow will persist
through the following 24-30 hours into Saturday evening, opted
for expansion of the Winter Storm Watch across all but a few of
our counties in south central South Dakota.

Will also have to watch wind speeds/gusts, though it looks like
a good portion of this event will have our area in a slacker
pressure gradient along the inverted trough. As such, while
localized areas of blowing snow are possible, the greatest
impacts to visibility and travel will come from the falling
snow, with widespread blowing snow not currently anticipated.

Snow will gradually taper off from west to east through Saturday
afternoon/evening as the system moves into the Great Lakes.

SUNDAY ONWARD: Sunday could still be a little breezy to start
the day, but winds decrease through the day as high pressure
slides into the area. Overall, this should be the better travel
day of the 3-day post-Thanksgiving weekend for the local area
with regard to weather conditions. However, cannot predict how
quickly roads will improve so be sure to check the latest road
conditions before heading out.

The first half of next week will feature a much colder air
mass, with temperatures further limited by expected widespread
snow cover. Low level (925-850MB) temperatures Sunday-Monday
will reside in the favored temperature range (DGZ: -12 to -18C)
for what I like to call insta-flurries, so cannot rule out
scattered flurries with any low cloud coverage. However, models
differ on the amount of moisture within this layer, so will not
introduce this to the forecast at this time.

The colder low levels will translate to surface temperatures
well below normal as we head into early December, though the
latest models do not keep the significant cold around for long
with an upward trend in temperatures by the middle of next week.
Still, will have to watch for possible sub-zero low temperatures
Sunday night in response to clearing skies/light winds and fresh
snowcover.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1017 PM CST Wed Nov 26 2025

VFR across most of the region. An area of MVFR and IFR due to a
thickening and lowering layer of stratus over east central South
Dakota and southwestern Minnesota. This area of stratus is expected
to expand southwest into southeastern South Dakota. At the same time
a region of low to mid clouds is flowing southeast from central
South Dakota. These clouds will work together to lower ceilings for
KHON and KFSD down to MVFR to high IFR at times. It is also possible
some patchy dense fog may form along and north of Highway 14 and
southwestern Minnesota where snowpack exists. Stratus and fog are
slow to burn off with most guidance holding on until late morning.
VFR conditions Thursday afternoon through the end of the period.

Winds will be light out of the north-northwest.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Watch from Friday afternoon through Saturday
     evening for SDZ040-055-056-061-062-065>071.
     Winter Storm Watch from Friday afternoon through Saturday
     afternoon for SDZ038-039-052>054-058>060.
MN...Winter Storm Watch from Friday afternoon through Saturday
     evening for MNZ071-072-080-081-089-090-097-098.
IA...Winter Storm Watch from Friday afternoon through Saturday
     evening for IAZ001>003-012>014-021-022.
     Winter Storm Watch from Friday afternoon through Saturday
     evening for IAZ020-031-032.
NE...Winter Storm Watch from Friday afternoon through Saturday
     evening for NEZ013-014.

&&

$$

DISCUSSION...JH
AVIATION...AJP