Severe Thunderstorm Warning 117, NWS Sioux Falls, SD

Area Forecast Discussion
National Weather Service Sioux Falls SD
847 PM CDT Mon Jun 15 2026

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms move southeast
  through late evening, diminishing after sunset and ending
  around midnight. Gusty winds of 40 to 50 mph may accompany
  these showers/storms through sunset.

- A band of showers and isolated thunderstorms are likely Tuesday
  evening and night, with the better chances northeast of a
  Huron to Spencer IA line. Severe weather is not expected.

- Wednesday will be windy as a spring-like system moves through.
  Gusts of 45 to 50 mph are likely. Scattered afternoon and
  evening showers may also bring additional gusty wind threats.

&&

.UPDATE...
Issued at 846 PM CDT Mon Jun 15 2026

Scattered showers and very isolated thunderstorms move southeast
through this evening, diminishing through the late evening hours.
Showers have been producing gusts at times earlier in the evening to
around 55 mph, but highest recent gusts have been closer to 50 mph
over the last hour. Rainfall amounts have been light given the very
high cloud bases - generally a couple hundredths of an inch or less
(outside thunderstorms). Activity should move out of the area by
midnight or a bit after.

Temperatures behind these showers are falling into the 60s, and fall
into the 50s later tonight. With some clouds around, it will be
another pleasant June night. Winds become a bit lighter overnight,
which may lead to some fog development in the James and MO River
Valleys, as well as between the James River Valley and the Buffalo
Ridge. Confidence is low given the spread in the models, but patchy
fog may reduce visibility into the early part of the Tuesday morning
commute.

No significant changes to Tuesday onward; see below for details.

&&

.DISCUSSION...
Issued at 1257 PM CDT Mon Jun 15 2026

Model soundings and the latest hi-res models continue to indicate
the potential for strong wind gusts with any shower and thunderstorm
activity that develops this afternoon and evening. These wind gusts
will be tied to surface based instability of about 200-500 J/kg.
Given the diurnal nature of this activity, the best chance for the
strong wind gusts will be roughly 4 pm to 9 pm. Only very isolated
activity will linger through about 10 pm to midnight. Otherwise a
little patchy fog will be possible around the Kingsbury and
Brookings county areas late tonight and early Tuesday morning.

An unseasonably strong jet max will dive southeast Tuesday into
Wednesday. As this jet max moves into the area Tuesday, warm
advection will increase with the chances for showers and isolated
thunderstorms arriving possibly during the afternoon, but the better
chances will be at night. While forcing is fairly strong,
instability is lacking due to a fairly deep dry layer in the lower
levels. However, with the EML running around 7.5 C and some decent
forcing, showers and isolated thunderstorms will be possible with
this shot of lift. The better chances appear to be near and
northeast of a Huron to Spencer IA line with the best chances in
southwest MN.

This almost spring or fall like system will bring strong surface
winds to the area Wednesday. Gusts of 45 to 50 mph will be likely
during the day as mixing brings down some very strong winds aloft.
The latest models show a 130 knot jet around 300 mb, with
unidirectional flow from the west northwest throughout the
atmosphere. While we will have a small convective threat on
Wednesday afternoon and evening, model soundings indicate weaker
instability than today, but still some 100-300 J/kg surface based
CAPE mainly north of I-90. With the strong, unidirectional winds,
wind gusts around 50 mph with these showers will be possible.

Broad troughiness moves through Thursday and should bring quieter
weather and seasonably cool conditions.

Weak upper level ridging builds on Friday and will keep quiet weather
in place with temperatures back into the upper 70s to mid 80s.

Saturday will see a system pass by, possibly a bit to the south.
However this will be the next better chance for showers and storms
with isolated severe storms possible. Something worth keeping an eye
on.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 618 PM CDT Mon Jun 15 2026

Showers and very isolated thunderstorms continue to move
southeast through the evening and may produce briefly stronger
wind gusts around 35-45 knots. Heavier precipitation may also
lead to a brief period of MVFR conditions. A storm moving into
northern Jerauld/southern Beadle county at the time of this
discussion should remain just south of KHON, so have left
mention of -TS out for now. Showers/isolated storms taper off
through the evening hours.

Otherwise, VFR conditions prevail through the period. Winds
through Tuesday afternoon generally remain northwesterly,
becoming more west-southwesterly from west to east to end the
period. Gusts tomorrow afternoon around 20 knots expected.

&&

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

&&

UPDATE...SG
DISCUSSION...08
AVIATION...SG

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
852 PM CDT Mon Jun 15 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-170200-
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-
852 PM CDT Mon Jun 15 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...Tonight.

Scattered showers and very isolated thunderstorms continue to move
southeast late this evening, diminishing around midnight. These
showers and isolated storms may produce wind gusts between 40 and 50
mph through 10 pm.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Better chances exist for more widespread showers and thunderstorms
Tuesday night into Wednesday morning. While the severe weather
potential is low at this time (10%), an occasional strong wind gust
up to 50 mph will be possible with some activity.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service Sioux Falls SD
508 PM CDT Mon Jun 15 2026

IAZ001>003-MNZ071-072-080-081-089-090-097-098-SDZ038>040-052>062-
064>067-160015-
Lyon-Osceola-Dickinson-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Beadle-Kingsbury-Brookings-Jerauld-Sanborn-Miner-
Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-Minnehaha-Douglas-
Hutchinson-Turner-
Including the cities of Rock Rapids, George, Inwood, Larchwood,
Sibley, Spirit Lake, Milford, Arnolds Park, Tyler, Hendricks,
Lake Benton, Ivanhoe, Marshall, Slayton, Fulda, Windom,
Mountain Lake, Worthington, Jackson, Lakefield, Pipestone,
Luverne, Huron, De Smet, Arlington, Lake Preston, Brookings,
Wessington Springs, Alpena, Woonsocket, Howard, Madison, Orland,
Flandreau, Chamberlain, Kimball, Plankinton, White Lake,
Stickney, Mitchell, Alexandria, Emery, Salem, Canistota,
Bridgewater, Montrose, Sioux Falls, Armour, Corsica, Delmont,
Parkston, Freeman, Menno, Tripp, Clayton, Parker, Centerville,
Marion, Viborg, Irene, Hurley, Chancellor, Canton, Lennox, Tea,
and Harrisburg
508 PM CDT Mon Jun 15 2026

...STRONG WIND GUSTS WITH INCOMING SHOWERS AND ISOLATED
THUNDERSTORMS EARLY THIS EVENING...

Scattered showers and isolated thunderstorms will bring occasional
wind gusts of 40 to 60 mph near and north of the Interstate 90
corridor early this evening. The main threat will be near and
west of I-29 through 7 pm, spreading east of I-29 from 6 pm to 8
pm.

If you have outdoor activities during this time and see showers
approaching, be prepared for a quick increase in the winds.

BP

Special Weather Statement
National Weather Service Sioux Falls SD
706 PM CDT Mon Jun 15 2026

IAZ001>003-MNZ071-072-080-081-089-090-097-098-SDZ038>040-052>062-
064>067-160215-
Lyon-Osceola-Dickinson-Lincoln-Murray-Cottonwood-Nobles-Jackson-
Pipestone-Rock-Beadle-Kingsbury-Brookings-Jerauld-Sanborn-Miner-
Lake-Moody-Brule-Aurora-Davison-Hanson-McCook-Minnehaha-Douglas-
Hutchinson-Turner-
Including the cities of Rock Rapids, George, Inwood, Larchwood,
Sibley, Spirit Lake, Milford, Arnolds Park, Tyler, Hendricks,
Lake Benton, Ivanhoe, Marshall, Slayton, Fulda, Windom,
Mountain Lake, Worthington, Jackson, Lakefield, Pipestone,
Luverne, Huron, De Smet, Arlington, Lake Preston, Brookings,
Wessington Springs, Alpena, Woonsocket, Howard, Madison, Orland,
Flandreau, Chamberlain, Kimball, Plankinton, White Lake,
Stickney, Mitchell, Alexandria, Emery, Salem, Canistota,
Bridgewater, Montrose, Sioux Falls, Armour, Corsica, Delmont,
Parkston, Freeman, Menno, Tripp, Clayton, Parker, Centerville,
Marion, Viborg, Irene, Hurley, Chancellor, Canton, Lennox, Tea,
and Harrisburg
706 PM CDT Mon Jun 15 2026

...STRONG WIND GUSTS WITH SHOWERS AND ISOLATED THUNDERSTORMS
THIS EVENING...

Scattered showers and isolated thunderstorms continue to bring
occasional wind gusts of 40 to 60 mph near and north of the
Interstate 90 corridor this evening. Showers and storms diminish
near and after sunset.

If you have outdoor activities through this evening and see
showers approaching, be prepared for a quick increase in the
winds.

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
733 PM CDT Mon Jun 15 2026

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

0650 PM     Tstm Wnd Gst     3 S Chamberlain         43.77N 99.32W
06/15/2026  M54 MPH          Brule              SD   ASOS

            ASOS station K9V9 Chamberlain Municipal
            Airport.

&&

AS