Severe Thunderstorm Warning 121, NWS Sioux Falls, SD

Area Forecast Discussion
National Weather Service Sioux Falls SD
145 PM CDT Wed Jun 17 2026

.KEY MESSAGES...

- Strong northwest winds will continue today with gusts of 40
  to 50 mph. A Wind Advisory will be in effect for the entire
  area until 9 pm this evening.

- Isolated to scattered showers this afternoon could result in
  slightly higher wind gusts (to 60 mph) during the afternoon.

- Isolated showers on Thursday could produce wind gusts to 40
  mph.

- Strong to severe storms could return on Saturday along with
  locally heavy rain. Specific details are uncertain, but as of
  now, the highest probabilities for severe storms remains south
  and west of the area.

&&

.DISCUSSION...
Issued at 144 PM CDT Wed Jun 17 2026

A strong jet max continues to wrap around the south side of an upper
level low, bringing strong winds to the area. Peak mixing suggests
that wind gusts could approach 50 mph. Model soundings also indicate
some weaker surface based instability this afternoon, which will
likely generate scattered showers and isolated thunderstorms. The
main concerns from any of this activity will be the potential to mix
down even stronger winds, possibly 60 to 65 mph. These stronger
winds will remain much more isolated.

Thursday will see deep, but weakening northwest flow across the
area. We will likely see a threat for isolated showers with locally
gusty winds to 40 mph as surface based peak mixing CAPE climbs to
about 200 J/kg.

Thursday night into Friday a weak wave will approach and bring some
elevated moisture return and very weak instability. For now any
impacts from this will be very minor.

The next system of interest will come Saturday, but with some
differences from model to model. The 6z EC Ensemble is bringing a 20-
30 percent chance for 2+" of rain to around the Missouri River into
parts of northwest IA while the 12z GFS ensemble and 12z Canadian
ensemble leave these better chances farther south and closer to I-
80. Classically the heavier rain many times falls between roughly
the surface to 850 mb boundary and for now that remains south of the
area, but will need to be monitored in case it drifts north.
Regardless, flooding potential is fairly low as rainfall has been
spotty at best lately.

Below normal temperatures and periodic chances for showers and
thunderstorms are expected Monday through Wednesday next week. A few
shortwaves are expected to move through, with slightly better
chances Monday and Wednesday.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1129 AM CDT Wed Jun 17 2026

MVFR ceilings should gradually lift through mid afternoon.
Northwest winds will gust to 45 to 55 mph at times, diminishing
this evening. Scattered showers and isolated thunderstorms
remain likely through the afternoon into the evening and could
produce localized wind gusts to 60 mph as well as very brief
heavy rain.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 9 PM CDT this evening for SDZ038>040-050-
     052>071.
MN...Wind Advisory until 9 PM CDT this evening for MNZ071-072-080-
     081-089-090-097-098.
IA...Wind Advisory until 9 PM CDT this evening for IAZ001>003-
     012>014-020>022-031-032.
NE...Wind Advisory until 9 PM CDT this evening for NEZ013-014.

&&

DISCUSSION...08
AVIATION...08

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
1020 AM CDT Wed Jun 17 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-181530-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Dixon-Dakota-Beadle-Kingsbury-Brookings-Gregory-
Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-
Minnehaha-Charles Mix-Douglas-Hutchinson-Turner-Bon Homme-Yankton-
Union-
1020 AM CDT Wed Jun 17 2026

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, southwest Minnesota, northeast Nebraska, central South
Dakota, east central South Dakota, south central South Dakota and
southeast South Dakota.

.DAY ONE...Today and tonight.

Strong west to northwest winds are anticipated with gusts averaging
40 and 50 mph at times before weakening this evening. Scattered
showers and isolated are expected this afternoon. While severe
storms are not anticipated, wind gusts could increase in very
localized locations to 50 to 60 mph.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Though uncertain, thunderstorm risks may increase by late Friday and
continue through Saturday. It is uncertain as to if severe storms
will be possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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Preliminary Local Storm Report
National Weather Service Sioux Falls SD
442 PM CDT Wed Jun 17 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0431 PM     Tstm Wnd Gst     4 N Dolton              43.54N 97.39W
06/17/2026  M62 MPH          McCook             SD   Mesonet

            Mesonet station 322 SD RWIS STANLEY CORNER.

&&

JC