594
FXUS63 KFSD 021938
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
238 PM CDT Tue Sep 2 2025

.KEY MESSAGES...

- Showers and storms are expected this afternoon and evening. A
  couple strong to severe storms are possible between 5 and 10
  PM with quarter size hail and 60 mph wind gusts being the
  primary threats.

- Additional, more widespread showers are expected later tonight
  into early Wednesday. Isolated rumbles of thunder but no
  severe weather expected.

- Canadian wildfire smoke moves into the region Wednesday. While
  the highest concentration should stay aloft, expect brief
  reductions to surface air quality and visibilities. Use
  caution and limit time outdoors if sensitive to smoke.

- Fall-like temperatures prevail mid to late week as an
  unseasonably strong system brings much colder air to the
  northern Plains and Upper Midwest. Mostly dry and periodically
  breezy conditions anticipated.

&&

.DISCUSSION...
Issued at 237 PM CDT Tue Sep 2 2025

NOW THROUGH TONIGHT: Wave moving through MN has kept some showers
and very isolated thunder across portions of southwestern MN. Expect
this to continue to move to the southeast through the early
afternoon. Attention turns to the cold front dropping south,
currently stretching from Sisseton to Redfield, SD where CU have
begun to develop. Convection has already begun to fire across west
central MN just ahead of the front, and expect more showers and
storms to develop near and along the front later this afternoon and
evening. Most CAMs still show the timing of the convection around 5
PM to 7 PM CDT for the US Hwy 14 corridor (22z-00z). This front
should push south of the area through this evening. A few strong to
severe storms are possible from roughly 5-10 PM with the aid of peak
heating. Instability around 1500 J/kg and shear around 25 knots may
be enough to help support a couple of stronger storms, although the
better shear (west) and instability (east) remain offset in time and
space. Main threats are hail to quarter sized with mid level lapse
rates around 6-6.5 deg C/km and wind gusts to 60 mph. With a weak
and subtle outflow boundary over the area and somewhat low LCL
heights, can`t entirely rule out a tornado; however, risk remains
very low. Could see some locally heavy rainfall with PWATs around
1.25-1.5" but expect storms to be progressive enough to limit any
issues.

Additional rain chances move in behind the main cold front with the
mid/upper level wave and a secondary, weaker lower level front.
Expect most of this precip to be focused across south central SD
into the MO River Valley, but should see widespread showers over the
area. Severe weather is not expected with this area of precip, but
may see some locally heavy rain. Lows tonight in the 50s. Winds
should remain elevated enough to preclude fog development.

MID WEEK: Showers and isolated storms continue to move south through
the morning hours Wednesday with the mid level wave and some focused
WAA near the wave. Showers may linger into the afternoon hours along
US Hwy 20, but should become more sparse in coverage. Otherwise, a
breezy and much cooler day is expected with strong low pressure over
southern Canada. Surface high pressure begins to move into the area,
with north to northwesterly flow through most of the atmosphere.
Given the northwesterly flow, cloud cover, and prevailing CAA have
leaned on the cooler guidance for highs tomorrow - keeping
temperatures in the 60s. You`ll definitely want a jacket as wind
gusts of 25-30 mph will make it feel cooler than the 60s.

One other concern for Wednesday is the Canadian wildfire smoke
filtering in behind the cold front. This could lead to some reduced
visibility and air quality, although the higher concentrations of
smoke should largely remain aloft. If you`re sensitive to smoke,
limit exposure and time outdoors. Smoke pushes south of the area
Wednesday evening and night. Lows Wednesday night fall into the
upper 30s to mid 40s. We may see some patchy frost in the

For Thursday, may see some minor lingering smoke aloft west of I-29,
but not expecting any surface impacts. Cooler temperatures aloft
prevail, with 850 mb temperatures in the lowest 10% of climatology.
However, with surface high pressure, southerly surface flow and
increasing WAA, should see highs moderate in the upper 60s to near
80 (in south central SD. By Thursday afternoon and evening, next
wave pivots southeast around the strong upper level low over Ontario
with a surface low swinging through MN. A cold front moves through
the area Thursday night; however, not expecting much if any
precipitation as low level moisture is lacking. Lows Thursday night
in the 40s.

FRIDAY-THE WEEKEND: Trough axis digs into the Midwest on Friday,
with ridging building to our west. With strong northwesterly flow,
Friday should be cooler with strong northwesterly winds. Should be
dry with surface high pressure. Highs in the 60s with lows in the
40s. Wind gusts 25-35 mph on Friday.

For the weekend, surface high pressure prevails. Still on the cooler
side Saturday as we remain under the influence of the mid/upper
level trough to the east. Similar temperatures Saturday with less
breezy conditions than Friday. By Sunday, this trough has moved into
Quebec, and ridging slides out of the Rockies flattening as it moves
east. We`ll be more in a westerly flow regime with some WAA
overhead with some moderation in temperatures.

EARLY NEXT WEEK: Rain chances return early next week with a short
wave and weak surface low moving through the region Monday into
Tuesday, although guidance is split on timing of this. Guidance then
splits with the GFS/ECMWF bringing ridging back to the area by
Tuesday, while the Canadian shows more troughing. Temperatures
should be near normal during this time.


&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1224 PM CDT Tue Sep 2 2025

A few concerns through the TAF period. Rain showers and isolated
lightning continues across southwestern MN through the early
afternoon hours, near/north of KMML and KTKC.

Next focus is the cold front moving through the region this
evening and into tonight. Scattered showers and storms are
expected to fire near the front. Expect the front near KHON
around 02.22-03.00z, KFSD between 03.01-03z, and KSUX around
09z. Have included a PROB30 mention at KHON and KFSD, but
omitted from KSUX as activity looks to stay to the east of the
airspace. Showers/storms could lead to MVFR conditions.

Showers and isolated storms develop behind the front, with the
heaviest focused for the James and MO River Valleys. Again,
could see MVFR/IFR conditions with this activity but too low
confidence on the timing to include. Showers should exit from
north to south through the late morning hours, lingering into
the afternoon along the MO River.

Finally, wildfire smoke aloft and at the surface move in behind
the front, leading to reduced visibility. Northwesterly winds
toward the end of the period will gust to around 25 knots.

&&

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

&&

$$

DISCUSSION...SG
AVIATION...SG