311
FXUS63 KFSD 262009
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
309 PM CDT Mon Oct 26 2026

.KEY MESSAGES...

- Rain is beginning to taper off south of I-90. Rain will
  continue to taper off from southwest to northeast through the
  overnight.

- There is around a 20-30% probability for overnight fog
  development in river valleys and low areas. Visibility may
  briefly decrease to 2 miles or less. Fog should burn off by
  mid-morning.

- An active pattern aloft will lead to additional rain chances
  on Wednesday and potentially over the weekend. Monitor your
  local forecast if you have any outdoor plans

- Near to slightly above normal temperatures will return from
  Wednesday onwards with daily highs in the low to upper 60s
  with a few low 70s at times.

&&

.DISCUSSION...
Issued at 306 PM CDT Mon Oct 26 2026

Light, periodic rain showers will continue through the remainder of
this afternoon and into the overnight, gradually dissipating
from southwest to northeast. A period of light drizzle is
possible as moisture wraps around the low in the early morning
hours of Tuesday. There is potential for fog to develop
overnight along river valleys and low areas. There is
approximately a 20-30% probability that visibility may briefly
fall to 2 miles or less. All shower activity should be northeast
of the CWA by around sunrise, and fog should burn off shortly
after. Overnight lows will dip into the upper 30s to mid 40s.
Thick, low stratus clouds linger into early Tuesday afternoon
before being swept away by a second shortwave moving through
western North Dakota. Winds become southerly and increase in
response to the tightened SPG. Gusts of 20-30 mph are possible
along and west of the James River Valley, with gusts generally
less than 20 mph to the east. Shallow mixing will tap into
strong WAA in the 925-850 mb layer. At the surface we can expect
highs to warm nicely into the low 50s to low 60s. The warmest
temperatures are expected over central South Dakota and
northeastern Iowa.

Wednesday morning lows will be warm for late October, in the 40s to
low 50s. Average lows this time of year are in the lower 30s.
Another day of light to breezy southerly winds and strong WAA will
warm our afternoon highs in the 60s and 70s. Similar to the lows, we
are quite warm for this time of year when average highs are
generally in the mid 50s. Around mid-morning a broad upper wave and
weak surface low will take shape over central Canada. An associated
cold front will drape from there southwest through central South
Dakota into southeast Wyoming. Light rain is expected to develop
along the front, mainly west of the James River late in the morning.
As the wave and frontal system move southeast rain will move into
the I-29 corridor and into western Minnesota and Iowa. Rain is
expected to be spotty in nature with little accumulation. Only a few
hundredths to a tenth or two. Showers clear out to the east after
midnight. Behind the front winds become northwesterly and light.
This will allow for good radiational cooling and lows will drop into
the mid 30s over central South Dakota to the upper 40s east of I-29.

Thursday winds aloft will become zonal to south-southwest. At the
surface high pressure builds in from the northwest. Winds will turn
southeasterly as that high scoots off to the east, but remain light.
Dry and mostly sunny conditions with highs in the low to mid 60s.
The majority of the day Friday will be dry with highs in the 60s.
Friday late afternoon and into Saturday another shortwave system
moves through bringing additional chances for rain. While currently
rainfall looks to be spotty and light, this could impact outdoor
Halloween plans. A brief break on Sunday before a much more
pronounced upper trough brings wide spread chances for
accumulating rainfall to the area Monday into late Tuesday.
While uncertainty is very high at this juncture, long term
ensemble guidance indicates the potential for widespread 0.5 to
1 inch. Stay tuned as we monitor the trends with this system and
details emerge.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1257 PM CDT Mon Oct 26 2026

A mix of VFR to IFR conditions will continue to degrade as clouds
thicken and lower. IFR ceilings and visibility are expected to
prevail through the late afternoon and overnight hours, with brief
periods of LIFR possible. Along with the low, thick clouds periodic
rain showers will continue into the early hours of Tuesday. As the
system responsible moves to the northeast showers will gradually
become lighter with periods of drizzle possible before moving east
of the CWA altogether, around sunrise. Though precipitation will
end, ceilings remain in the IFR category for much of the remaining
period.

Winds are out of the northeast and slightly breezy with gusts of 15-
20 kts expected. Winds will decrease after sunset as the surface low
pushes through the region, becoming light and variable through
Tuesday morning. Breezy southwest winds gusting to 25 kts will push
into central South Dakota near the end of the period.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...AJP