856
FXUS63 KFSD 152336
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
536 PM CST Mon Dec 15 2025

.KEY MESSAGES...

- Fog potential for late tonight into Tuesday morning
  increasing. Best chance should be east of the James River and
  especially in northwest IA and nearby locations.

- Wednesday afternoon into Thursday will see strong winds with
  a small chance for light snow/blowing snow. The snow chance
  will come with the cold surge on Wednesday night into Thursday
  morning. Because winds could exceed 50 mph, any snow that
  falls could cause rapid drops in visibility in a short time.

- Cooldown with mid-week system will be brief, with seasonably
  mild temperatures returning Friday into the weekend.

- The chance for impactful precipitation looks to be fairly low
  over the next 2 weeks.

&&

.DISCUSSION...
Issued at 217 PM CST Mon Dec 15 2025

Southerly flow gradually increases tonight ahead of an incoming wave
that will track by to the north of the area. This will continue with
somewhat mild overnight temperatures, although winds at the surface
will remain on the lighter side. With a building inversion and
slightly higher moisture near the surface some fog will be possible
on Tuesday morning. The better chances should be across areas with
melting snowpack, which would be mostly east of the James River, but
really could end up about anywhere. The latest HREF indicating about
a 30-60 percent chance for some lower visibilities in fog late
tonight into Tuesday morning.

The wave tracking by to the north will bring a cool front into the
area but have little effect on temperatures and not bring any
precipitation. Some moisture aloft moves through, but moisture below
about 700 mb is scant.

Wednesday will see a quick return to southerly flow ahead of a much
stronger upper level jet/wave. This will keep mild temperatures in
place and continue to eat away at the snow cover in place. Highs
likely from the upper 30s to lower 40s over the remaining deeper
snow pack to some 50s west of the James River. Winds ahead of this
wave Wednesday afternoon may become very strong, mainly west of the
James River where deeper mixing is more likely. At least a small
chance for some fire weather concerns in these areas. Suspect
southwest winds will gust around 40 mph.

Wednesday night into Thursday morning continues to pose the most
concern over the next several days. While the wind may end up being
the only concern, the potential strength of the wave on the backside
of the upper trough that is driving the very strong cold advection
during this time could generate some light snow via convective and
saturation of the DGZ. This could result in enough light snow to
reduce the visibility with these stronger winds. Not enough
confidence and too far in advance to do anything other than continue
to monitor the trends. Stay tuned to updates for this potentially
short term hazardous weather potential. As for the wind, model
soundings fairly consistent on generating some very strong winds
aloft that in many locations should mix down, especially west of I-
29 where snow should melt the most over the next 3 days. Suspect
wind gusts of 50-60 mph will occur near and west of I-29 from about
9z Thursday through 15z Thursday, with 40 to 50 mph winds more
likely east of I-29. Parts of southwest MN may become snow free by
Thursday as well and could see an increased threat for higher winds
with deeper mixing.

Friday through early next week will see fast upper level jet energy
which supports a pattern of a few ups and downs without much chance
for significant precipitation or major cold outbreaks.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 535 PM CST Mon Dec 15 2025

VFR conditions begin the TAF period. Light and variable winds will
persist through the evening hours before slowly picking up out of
the south for the overnight time frame. At the same time, patchy fog
is possible this evening and night as well. Confidence is only high
enough to include mist at KFSD though trends will be monitored. The
southerly winds will turn to out of the west/northwest by the
afternoon hours tomorrow with gusts increasing up to 15 to 25 knots.
Low level wind shear will prevail throughout the TAF period though
will be most prominent during the afternoon hours tomorrow.

&&

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

&&

$$

DISCUSSION...08
AVIATION...Meyers