137
FXUS63 KFSD 231750 AAB
AFDFSD

Area Forecast Discussion...UPDATED
National Weather Service Sioux Falls SD
1150 AM CST Sun Nov 23 2025

.KEY MESSAGES...

- Another round of fog is expected overnight tonight through
  Monday morning, particularly over the James River Valley east
  through southwestern Minnesota and northwestern Iowa.

- High temperatures today will range from the mid 50s to low
  60s, highest west of the James River Valley. These reading are
  around 15 degrees above normal. Highs Wednesday through at
  least next Sunday will be around 10 degrees below normal.
  Highs will be mainly in the mid 20s and 30s.

- There is around a 40 percent chance of light rain over far
  southeastern South Dakota, northwestern Iowa, and southwestern
  Minnesota on Monday. Total rainfall amounts are expected to
  stay under a tenth of an inch.

- There is a 40 percent chance of mainly light snow Tuesday
  afternoon into Tuesday evening over mainly east central South
  Dakota. Snowfall amounts are currently forecast to be less
  than 1 inch.

- Winds Tuesday will be out of the northwest gusting 25 to 35
  mph over far northeastern Nebraska, southwestern Minnesota,
  and northwestern Iowa. The strongest winds, gusting 35 to
  around 45 mph will be west of the James River. The combination
  of little to no precipitation and strong winds may result in
  high Grassland Fire Danger Index values over portions of south
  central South Dakota on Tuesday (mainly Gregory County).

&&

.UPDATE...
Issued at 1140 AM CST Sun Nov 23 2025

Updated discussion for the 18Z TAFs below.

&&

.DISCUSSION...
Issued at 425 PM CST Sat Nov 22 2025

A surface trough will push across western and central South
Dakota during the day today. Dry weather will continue.
Temperatures today will again rise into the mid 50s to low 60s.

Winds today will be out of the south 10 to 15 mph with gusts up
to around 25 mph. Relative humidity values will fall to around
50 percent, except fall into the 35 to 45 percent range west of
the James River.

Increased moisture will move in Monday and remain through the
rest of the week. Patchy fog is expected Monday morning over
much of the area. There is around a 40 percent chance of light
rain over far southeastern South Dakota, northwestern Iowa, and
southwestern Minnesota on Monday as a surface low crosses the
Central Plains. Total rainfall amounts are expected to stay
under a tenth of an inch.

A cold front sinking across the area Monday will result in
slightly cooler air, with highs Monday still in the 50s.

The main concern for Monday evening onward is snow and winds on
Tuesday and falling temperatures through the week. To start, there
will be rain moving into northern SD Monday night that will slowly
change over to a rain/snow mix then snow Tuesday morning, with 50-
70% chance for precipitation to occur over northeastern SD during
the day Tuesday. There is a 20-45% chance for precipitation to occur
over southeast SD, southwest MN, and northwest IA during the day
Tuesday. For this area, the transition from rain to a rain/snow mix
is forecast to occur Tuesday afternoon then snow late in the
afternoon. Snow chances then move out of eastern SD as well as
southwest MN, and northwest IA during Tuesday evening. The surface
low pressure that will be moving this precipitation into the area
has shifted more to the north in the past few models runs, which has
caused the higher snowfall amounts to move further to the north than
previous forecast. There is a 30-60% chance for greater than an inch
of snow to fall over northeastern SD, with the highest chances over
the northern Prairie Coteau around 3 inches. Additionally the
probability for a half inch or more of snowfall is around or greater
than 20% north of US HWY 14, with the chances increasing to the
north.

With the stronger low pressure to the northeast and high pressure
building to the west of SD, a tight pressure gradient over the state
forms Monday night into Tuesday. This tight pressure gradient along
with the stronger CAA occurring during this time will help to develop
strong winds and get these winds down to the surface. Model
ensembles are showing a 30-50% chance for winds to gust greater than
45mph over areas west of the James River Tuesday morning and
afternoon. South central SD has the highest chances for these wind
gusts, around 50-70% chance for greater than 45mph and 30-50% chance
for greater than 50mph. These stronger winds could cause blowing
snow to occur Tuesday, which would create hazardous traveling
conditions in areas by reducing visibilities.

The cold air advecting in to the area will cause our above average
temperatures to drop Monday evening through the week. By Thursday
and into the weekend, the temperature will be 5-10 degrees colder
than normal, with highs in the low 20s to low 30s and low
temperatures in the teens to single digits. High surface pressure is
forecast to move over central and eastern SD, northwest IA,
southwest MN, and northeast NE Tuesday night. This high pressure
will help to keep things dry Wednesday and Thursday. After this, the
models have a lot of variability in the next system that could move
through the area, creating a lot of uncertainty. An eye will have to
be kept on this time period in the next couple of days to see if the
models start to come to a better agreement.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1140 AM CST Sun Nov 23 2025

VFR conditions are forecast to prevail through this evening as
fog is forecast to develop over the region late tonight through
Monday morning, particularly over the James River Valley east
through southwestern Minnesota and northwestern Iowa. Drop in
cigs to IFR to possibly LIFR is forecast at this time for areas
that could receive fog.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

UPDATE...MMM
DISCUSSION...06/12
AVIATION...MMM