870
FXUS63 KFSD 211730
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1130 AM CST Fri Nov 21 2025

.KEY MESSAGES...

- Warm conditions are expected today through the weekend. Highs
  will be in the 50s today, with 50s and 60s Saturday and
  Sunday.

- A change is coming for next week. There is a moderate (40-70%)
  chance for precipitation beginning Monday morning and
  continuing through Tuesday morning. Uncertainty remains in
  timing and location of highest amounts, but temperature
  profiles indicate that the precipitation type will be rain.

- The changes continues with much colder temperatures expected
  beginning the middle of next week through the weekend.

&&

.DISCUSSION...
Issued at 333 AM CST Fri Nov 21 2025

Patchy dense fog has developed across the region. With lows falling
to below freezing, there is also risk of fog freezing on flat
surfaces and roadways, creating slippery spots. Visibility may fall
to less than one mile at times. The lowest visibilities are mostly
confined to low laying areas and river valleys, west of the James
River, and in northwestern Iowa. Be prepared for rapidly changing
conditions as you make your way this morning. Fog should burn off by
mid-morning.

Today will be a pleasant day thanks to surface high pressure and
moderate warming in the mid-levels. The 925 mb layer is expected to
warm between 6 and 8 degrees C. Mixing this down to the surface will
result in highs in the upper 40s to a few 50s over south central
South Dakota. Lows will fall to the upper 20s and mid 30s overnight.
Scattered to broken clouds will hang around for most of the day as a
mid-level wave passes to our south. Thickest clouds are expected
through the Highway 20 corridor and south. Winds will be light and
variable through the afternoon, gradually becoming southerly as the
high pressure progresses east of the region. Saturday will be even
warmer thanks to WAA and plentiful sunshine. The latest 21.00Z
guidance has remained on track with previous runs indicating high
temperatures will climb into the 50s, with 60s possible along the
southern Missouri River counties. A weak frontal boundary makes its
way southeast through the region during the day, gradually turning
winds to the northwest by the afternoon. Winds will be slightly
breezy behind the boundary, gusting 15 to 20 mph. Winds become light
and variable again overnight. Mostly clear skies will allow for good
radiational cooling, and so lows will fall into the upper 20s to low
30s. Patchy dense fog may be possible again Saturday morning. Sunday
a surface high pressure passes through the region, gradually turning
winds southerly and warming highs once again into the 50s. A few
more 60s may be possible, this time over south central South Dakota.
Clouds build in as an upper low pressure system approaches from
the desert southwest, keeping lows a bit warmer in the mid to
upper 30s.

Meanwhile, the previously mentioned upper low located over the
desert southwest will eject out onto the central Plains late Sunday
afternoon and progress northeastward toward our area. Thermodynamic
profiles indicate the air column to be solidly above freezing,
therefore the precipitation type will be rain. Rain begins as early
as daybreak Monday and continues through early Tuesday morning.
Despite clouds and rain, southerly winds and WAA keep Monday`s highs
in the 50s for most of the region. As the system departs Tuesday
morning another will be right on its heels. A trough digging south
over the eastern Rockies and associated surface low pressure will
drag a strong cold front through much of the central and northern
Plains Tuesday. Winds will turn west-northwesterly and become
strong. By Tuesday afternoon gusts of 25-35 mph will be common for
areas along and east of the James River. Even stronger winds are
possible for the west, with gusts 35-40 mph or stronger. With the
winds comes strong CAA that begins to cool the mid-levels. Highs
will be much closer to seasonal averages, in the upper 30s to low
40s. Continued strong CAA overnight will decrease lows by
Wednesday morning into the low 20s with wind chills in the
single digits.

As the trough axis passes overhead during the day Wednesday there is
a low chance for precipitation along and north of Highway 14. Mid-
term guidance is in low agreement on how far south precipitation
will intrude. What they are in agreement on is the continued cold
weather and gusty winds. Highs for Wednesday will only climb to the
upper 20s to low 30s north of I-90, and mid 30s to the south. Wind
chills will be in the teens to low 20s. Cold weather continues as
you gather for your favorite meals Thursday, with highs only
climbing to the upper 20s and low 30s. Friday highs will be very
similar. Please ensure you are prepared for the cold weather next
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1128 AM CST Fri Nov 21 2025

Any lingering fog will burn off quickly early this afternoon, with
only low (<20%) chance of fog redevelopment early tomorrow morning.
The main reason why fog looks less likely tonight is because winds
will be slightly elevated compared to last night, around 5 kts.
Speaking of winds, look for winds to slightly increase through
tomorrow morning to around 8-12 kts to end of the period. Winds
will be mainly out of the south tonight, turning gradually to
the west through tomorrow morning as a weak frontal boundary
moves into the area.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...Samet