442
FXUS63 KFSD 030832
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
332 AM CDT Wed Sep 3 2025

.KEY MESSAGES...

- Scattered shower with a few isolated rumble of thunder will
  continue through the late morning mainly across portions of
  southeastern SD.

- Canadian Wildfire smoke will filter into the region today.
  While the highest concentration should stay aloft, Minor
  reductions in surface visibilities and air quality will be
  possible. If you`re apart of a sensitive group, make sure to
  monitor your local air quality.

- Next shower and thunderstorm chances (40%-60%) likely occur
  by Thursday afternoon mainly along and east of I-29. While the
  severe weather risk is low, pockets of locally heavy rainfall
  will be possible.

- Fall-like temperatures will continue into into the weekend as
  an unseasonably strong system brings much cooler air to the
  northern plains/upper midwest.

&&

.DISCUSSION...
Issued at 328 AM CDT Wed Sep 3 2025

TODAY & TONIGHT: Much cooler conditions ahead! Taking a look across
the area, scattered showers continue to progress southeastwards out
of northcentral and northwestern SD this morning mostly in response
to increasing lift with a mid-level wave and the nose of an upper-
level jet. While this could lead to more widespread development
mainly over southeastern SD, limited instability (<300 J/kg) should
keep any severe weather chances at bay. Instead, increasing 700 mb
frontogenesis should lead to an enhanced band of showers developing
somewhere between the Missouri River Valley and I-90 corridor in
southeastern SD. While mostly light accumulations are expected,
there could be a pocket of 0.30" of an inch or higher in the
areas where that band set up. Nonetheless, as this developing
area of showers continues to gradually progress southeastwards
with time; should see most of this activity push out of our area
by the early afternoon (11am-1pm).

From here, the focus shifts towards the smoke as northerly to
northwesterly mid-level flow ushers in another plume of canadian
wildfire smoke. While the higher concentrations will likely stay
aloft, minor reductions to air quality and visibility are expected
especially along and west of I-29. With this in mind, make sure to
keep an eye on your local air quality especially if you`re apart of
a sensitive group and/or have any outdoor events planned. Otherwise,
a much cooler and breezy day will be on tap as highs only peak in
the low to upper 60s with wind gusts in the 15-25 mph range during
the afternoon hours. Lastly, the cooler conditions will continue
overnight as a combination of cold air advection (CAA) aloft and
lighter surface winds lead to temperatures in the upper 30s to mid
40s across the area. With the coldest conditions likely along the
eastern side of the Chateau Des Prairies, can`t completely rule out
some patchy frost in portions of the Buffalo Ridge. With this in
mind, make sure to cover/move any temperature sensitive plants
indoors where possible.

THURSDAY & FRIDAY: Looking into the latter parts of the week, an
active pattern continues aloft by Thursday an a clipper wave rotates
around a parent upper-level low (ULL) sitting over the Ontario
Province in Canada. Dubbed the "angry clipper" by one of our
surrounding offices, we`ll likely see this decently strong wave
aggressively rotate across the Northern Plains and Great Lakes
Regions with its associated cold front bringing increasing rain
chances to the region. For our area specifically, the focus will be
on areas along and east of I-29 as a low CAPE/high shear environment
leads to the development of scattered showers and thunderstorms for
the second half of Thursday. While severe weather is not expected
due to the limited instability (<500 J/kg), can`t rule out pockets
of locally heavy rainfall especially across southwestern MN given
the copious amounts of shear (30-50 kts) in the low levels.

Nonetheless, should see most of this activity continue to progress
southeastwards out of our area during the evening hours (7pm-9pm).
Otherwise, expect much breezier conditions on Thursday as a
tightening SPG leads to wind gusts in the 30-40 mph mainly west of I-
29. By Friday, could see some spotty sprinkles to light showers
develop across areas north of I-90 as another ribbon of lift rotates
around the previously mentioned ULL. While light accumulations will
be possible not expecting much more than a few hundredths at best.
The breezy conditions will also continue by Friday afternoon with
wind gusts between 20-30 mph expected. Lastly, temperatures will
continue to trend below normal for the period with highs mainly in
the 60s and 70s. However, could see a briefly warmer temperatures on
Thursday as a combination of southerly to southwesterly flow and a
strong push of mid-level warm air advection (WAA) leads to a few
low 80s mainly across southcentral SD.

SATURDAY ONWARDS: Heading into the extended period, heights will
continue to rise over the western CONUS as an upper-level ridge
builds and gradually pushes eastwards. surface to mid-level ridging
will move into the Plains by Saturday returning us to much quiet
conditions. While temperatures will continue to stay below normal
for the rest of the weekend, increasing mid-level WAA and an
eventual return to southeasterly surface winds should help highs
gradually recover to upper 60s to 70s by Sunday. Otherwise, expect
rain chances (20%-30%) to temporarily return by late Monday as
another mid-level wave progresses through our area. While the severe
weather risk is low, some long-range guidance does suggest enough
instability (600-1000 J/kg) for some isolated thunderstorm though
shear is rather limited (15-25kts). Nonetheless, this will be our
next period to watch for any organized activity.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1040 PM CDT Tue Sep 2 2025

A couple areas of leftover showers/isolated thunderstorms east
of Interstate 29 will continue to slide to the southeast out of
the area. Otherwise, additional showers and isolated
thunderstorms will push across the area later tonight, with more
of the focus being through the James and MO River Valleys, and
then into parts of northwest IA by Wednesday morning. Guidance
is indicating MVFR stratus developing over these same areas with
this activity on Wednesday morning. These showers will
completely exit the area by late morning on Wednesday.

Behind this, wildfire smoke will work into the region, and some
of this may reach the surface with some reduction in visibility
possible. Winds will transition to northerly behind a frontal
boundary overnight, gusting around 20 kts on Wednesday.

&&

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

&&

$$

DISCUSSION...05
AVIATION...JM