112
FXUS63 KFSD 221040
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
540 AM CDT Sat Aug 22 2026

.KEY MESSAGES...

- Slightly cooler weather for the weekend. Today will remain dry
  with moderate rain chances (40-70%) returning to portions of
  the area Sunday through Sunday night. Rainfall amounts could
  exceed a tenth to a quarter of an inch.

- Additional chances for rain, and potentially strong to severe
  thunderstorms (5-15%), are possible through next week, though
  details are uncertain. Continue to check the latest forecast
  for the most up to date information.

&&

.UPDATE...
Issued at 420 AM CDT Sat Aug 22 2026

A quiet night continues and thunderstorms have remained south
of the forecast area as anticipated. Light winds and optimized
radiational cooling have allowed for shallow/patchy fog
development in portions of northwest Iowa. Will monitor trends,
but at this time, do not expect any headlines will be needed.

Today should be a pleasant day with abundant sunshine. While
there may still be a slight haze from smoke aloft, models show
lower concentrations working into the area through the day.

Daytime rain/storm chances for Sunday remain focused mainly west
of the James River Valley, with increased chances expanding east
through the evening into Monday morning. SPC has maintained a
Level 1 of 5 risk for severe storms in areas west of I-29 for
this activity, with isolated damaging winds/large hail possible.
However, model soundings would also indicate a potential for
locally heavier rainfall with moistening profiles leading to
precipitable water approaching 2 inches.

&&

.DISCUSSION...
Issued at 139 PM CDT Fri Aug 21 2026

Quiet conditions persist this afternoon as temperatures have warmed
to the 70s and 80s across the area. Quiet conditions are expected to
continue for the rest of the day as the cold front has fully pushed
through the area. This will keep storm chances south and west of the
forecast area. Can`t rule out the low possibility (less than 20%) of
a shower or weak storm passing along and south of the Missouri River
this afternoon, evening, and potentially into the overnight hours.
Should this occur, the chance for a severe storm is low. Surface
ridging will begin to slide into the forecast area tonight,
resulting in light and variable winds with lows falling to the upper
50s to low 60s. Patchy fog is again on the table but with drier air
in place, think that any fog that does develop will once again be
tied to a few river valley`s.

Saturday begins the weekend on the quiet side as high pressure
pushes through the Northern Plains. High temperatures will be a bit
cooler in the upper 70s to low to mid 80s, with a continuation of
light northerly winds. This will make for a wonderful Saturday,
perfect for outdoor activities! Rain chances will increase late
Saturday night through Sunday as a weak shortwave trough rounds the
top of a building upper level ridge. This will result in increasing
chances for rain across the area for the day on Sunday. Cloud cover
with the associated chances for rain will keep high temperatures a
bit cooler in the upper 70s to low 80s. While some showers are
possible during the morning timeframe, the highest chances for rain
will come Sunday evening and night as the main shortwave pushes
through the area. The ensembles show a broad 40-70% chance for
rainfall totals to exceed a tenth of an inch. Soundings show some
elevated instability in place so thunderstorms are possible, though
severe storms are not expected at this time due to weak shear
profiles. With non-severe storms on the table, rainfall amounts
could be locally higher depending on how storms track.

An active pattern continues aloft for next week. Medium range
guidance shows shortwave troughs continuing to push through the
Northern Plains within the northwest flow regime. This will lead to
chances for rain almost every day next week. However, the ensembles
show a large variance in rainfall probabilities due to the
differences in these upper level features. Latest machine learning
(ML) guidance does show low probabilities (5-15%) for severe weather
throughout the week. Details for severe weather remains uncertain so
continue to check the forecast for the most up to date information.
Aside from rain and storm chances, high temperatures look to remain
in the upper 70s and 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 540 AM CDT Sat Aug 22 2026

Patchy early morning fog, mainly in northwest Iowa, will locally
reduce visibility to IFR levels early in the period. Otherwise,
VFR conditions and light north winds generally at or below 12kt
through sunset. Winds become light and variable tonight with VFR
conditions expected to dominate across the area.

&&

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

&&

$$

UPDATE...JH
DISCUSSION...Meyers
AVIATION...JH