811
FXUS63 KFSD 251245
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
645 AM CST Tue Nov 25 2025

.KEY MESSAGES...

- Areas of dense fog have been expanding in portions of
  northwest Iowa and Siouxland early this morning. A Dense Fog
  Advisory is in effect along/south of a Vermillion SD to Orange
  City and Spencer IA line until 9 AM.

- Strong northwest winds are expected today with gusts 45 to 60
  mph. The strongest winds will impact south central South
  Dakota, where a High Wind Warning is in effect.

- A southward trend in the storm track has increased forecast
  snow totals, especially north of I-90. Accumulations of 2 to 4
  inches are now expected in portions of southwest Minnesota,
  tapering to an inch or less along and south of South Dakota
  portions of I-90.

- The combination of strong winds and snowfall will lead to
  reduced visibility (1/2 mile or less at times) in falling
  and/or blowing snow, especially in portions of east central
  South Dakota/southwest Minnesota where Winter Storm Warnings
  and Winter Weather Advisories have been issued.

- Watch for flash freeze this evening as temperatures plunge
  into the 20s. Much colder air persists for the rest of the
  week and through the Thanksgiving holiday weekend.

- While details remain unclear, chances for accumulating snow
  return Friday into the weekend.

&&

.DISCUSSION...
Issued at 505 AM CST Tue Nov 25 2025

Focus for this morning, beyond the areas of dense fog expanding
in southeast portions of the CWA, will be on a southward trend
in accumulating snow potential for later today and tonight. 00Z
models show remarkable agreement that the southern end of the
precipitation shield associated with a compact storm system will
extend farther south than previous model runs, though still only
moderate confidence in snowfall totals given the abrupt change
and an expected sharp southern edge to precipitation which is
still expected to be somewhere in our central to northern CWA.

Precipitation amounts across the northern 2-3 tiers of counties
(east central SD and southwest MN) more than doubled over just
12 hours ago as the storm trended slightly farther south and
slower than previous forecasts. This now results in moderate to
high probabilities (50-90% south to north) of snowfall exceeding
1 inch north of I-90, with low to moderate (20-50% west to east)
probability of exceeding 4 inches along the Highway 14 corridor
and into portions of MN Highway 30.

Unfortunately, the potential for strong winds accompanying the
storm system has not changed, and as such, we are looking at a
period of gusts 45 to 55 mph today into tonight, coincident with
and following the transition from rain to snow. 00Z HREF shows
low to moderate (30-40%) probability that snowfall rates could
reach an inch per hour in the aforementioned areas (Highway 14
and into MN Highway 30) during the late afternoon to early
evening, or about evening commute time. These snowfall rates
alone could drop visibility to a half mile or less, but when
combined with the expected strong winds, we cannot rule out the
possibility of brief blizzard or snow squall conditions. For
now, given some lingering uncertainty due to the sudden change
in the models, coordinated with neighbors to issue a Winter
Storm Warning where the greatest snowfall (2 to 4 inches) is
more likely in southwest Minnesota. This will be buffered by a
narrow Winter Weather Advisory, with both headlines covering the
combination of accumulating snow and blowing snow.

Snow should exit the area after midnight tonight, but the strong
winds gusting 40 to 50 mph will taper off more slowly, with
patchy blowing snow remaining a factor into early Wednesday
morning.

Limited time to look at the latter part of the Thanksgiving
holiday weekend this morning, but models continue to show a
moderate (50-70%) chance for additional accumulating snow moving
across the area Friday into Saturday/Saturday night. Confidence
is higher that below normal temperatures will persist through
the holiday weekend and into early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 641 AM CST Tue Nov 25 2025

An area of dense fog with VLIFR visibility and LIFR ceilings
blankets much of northwest Iowa and adjacent areas to start this
period. This should improve rather quickly from west to east by
mid-morning as winds begin to increase from the west-northwest.

Otherwise a sharp cold front will move across the area today,
followed by strong to damaging northwest winds gusting 40-50kt
at times. Areas of light rain will change to snow as the colder
temperatures move in, producing IFR-LIFR visibility in -SN and
areas of BLSN. Worst conditions with regard to snow are expected
north of I-90.

Sub-VFR conditions begin to improve west of I-29 late in this
period, though wind gusts 30-35kt are expected to continue
through daybreak Wednesday.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 9 AM CST this morning for SDZ070-071.
     Wind Advisory until midnight CST tonight for SDZ068>071.
     Wind Advisory until 6 PM CST this evening for SDZ038-052-053-
     058-059-064.
     Winter Weather Advisory from noon today to midnight CST
     tonight for SDZ038>040-055-056.
     Wind Advisory from noon today to midnight CST tonight for
     SDZ039-040-054>056-060>062-065>067.
     High Wind Warning until 6 PM CST this evening for SDZ050-057-
     063.
MN...Wind Advisory from 3 PM this afternoon to 3 AM CST Wednesday
     for MNZ089-090-097-098.
     Winter Storm Warning from 3 PM this afternoon to 3 AM CST
     Wednesday for MNZ071-072-080-081.
     Winter Weather Advisory from 3 PM this afternoon to 3 AM CST
     Wednesday for MNZ089-090-097.
IA...Wind Advisory from 3 PM this afternoon to 3 AM CST Wednesday
     for IAZ001>003-012>014-021-022-032.
     Dense Fog Advisory until 9 AM CST this morning for IAZ012>014-
     020>022-031-032.
     Wind Advisory until midnight CST tonight for IAZ020-031.
NE...Dense Fog Advisory until 9 AM CST this morning for NEZ013-014.
     Wind Advisory until midnight CST tonight for NEZ013-014.

&&

$$

DISCUSSION...JH
AVIATION...JH