167
FXUS63 KFSD 261122
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
622 AM CDT Wed Aug 26 2026

.KEY MESSAGES...

- Seasonable temperatures and dry weather prevails through
  Thursday with highs in the upper 70s and 80s, and lows in the
  50s to lower 60s.

- Warmer and more humid air returns Friday through the weekend
  with moderate (40-60%) chances for storms late Friday into
  Friday night.

- Periodic shower and storm chances continue this weekend into
  early next week. Confidence on any details is low.

&&

.UPDATE...
Issued at 435 AM CDT Wed Aug 26 2026

A quiet night continues with clear skies and light winds. Seeing
some shallow valley fog creep northward through western Iowa, so
may have to watch for this toward Highway 20 to perhaps Highway 3
by daybreak, but webcams still look pretty clear to this point.

Still seeing a moderate (40-60%) chance for storms developing
Friday evening, especially west of I-29. SPC has outlined this
area in the latest Day 3 outlook, with a Level 1 of 5 risk for
severe storms. A lower confidence scenario due to variability in
timing of a mid-level wave and location of the nocturnal low level
jet, but late day instability and deep layer shear could support
a few stronger storms if the other parameters come together. With
high school football now underway, those with outdoor plans will
want to monitor the forecast closely and stay weather aware.

&&

.DISCUSSION...
Issued at 1244 PM CDT Tue Aug 25 2026

Wednesday and Thursday both look dry and seasonally warm as surface
pressure noses in and slowly drifts east. With relatively light
northerly flow in place both days, lows will generally be in the
50s, a few 60s on Wednesday morning, with highs in the lower to mid
80s.

Thursday night into Friday weaker upper level ridging moves through
as a trough of low pressure deepens over the Northern Rockies. This
trough will continue to dig into the weekend, then expected to
spread across the Canadian border later Sunday into Monday.

This pattern change to southwest flow aloft continues into next
week and will likely bring periods of showers and thunderstorms.
The best chance for now looks to be Friday night as the upper
level ridge is shoved east and warmer and more moist airs builds
in. Initially Friday the area looks too capped to produce showers
and thunderstorms. Maybe some ACCAS activity on Friday morning
but even that looks like a low probability.

The main piece of energy with this initial push moves through Friday
night and should bring scattered showers and thunderstorms. For now
the severe weather threat appears to be fairly low. Another wave
moves into the Western High Plains on Saturday which should bring
enhanced heating ahead of a weak front. This could be a brief period
of thunderstorms and isolated severe, but too far out to determine
just yet. Moderate shear and minor to moderate instability are
possible.

Sunday into Monday gets a bit messier with some timing difference on
the exiting and lifting northeast of the main upper level jet. The
models suggest that the right entrance region will exit to the
northeast sometime Sunday night into Monday afternoon which could
serve as our next better chance for showers and thunderstorms.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 620 AM CDT Wed Aug 26 2026

VFR conditions will prevail through the period, with perhaps a few
afternoon cumulus around 4-6kft AGL. The afternoon hours may also
see occasional gusts 18-25kt out of the northwest to north, but
any gusts will quickly subside before sunset.

&&

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

&&

$$

UPDATE...JH
DISCUSSION...08
AVIATION...JH