Severe Thunderstorm Warning 103, NWS Sioux Falls, SD

Area Forecast Discussion
National Weather Service Sioux Falls SD
637 PM CDT Thu Jun 4 2026

.KEY MESSAGES...

- Scattered strong to severe storms remain possible through
  about 1 am tonight mainly near and north of Highway 14 and
  into south-central South Dakota. 70 mph winds and ping pong
  ball sized hail will be the main threats, though tornadoes
  cannot be ruled out.

- Good agreement on the better chance for scattered
  thunderstorms containing heavy rain to be generally near
  Highway 14 into tonight. Saturated grounds from last night's
  storms could lead to some minor flash flooding and potentially minor
  river flooding.

- While details are far more uncertain, an isolated to
  scattered severe storm risk will linger into Friday. The
  greater risks at this time shift southeast into eastern
  Nebraska, Iowa and far southern Minnesota.

- Temperatures heat up next week. There is an increasing chance
  (30-60%) of highs exceeding 95 degrees especially near and
  west of the James River by Wednesday and Thursday.

&&

.DISCUSSION...
Issued at 336 PM CDT Thu Jun 4 2026

Several boundaries, some left behind from yesterday's
storms, are noted across the area by agitated lines of CU and
ongoing thunderstorms. Ample sunshine in these areas prior to
development has led to 1,500-2,000 J/kg to develop with mid-
level lapse rates around 7.5 C/km. Shear is on the weaker side,
but large hail to ping pong balls will still be possible given
the lapse rates. And with the myriad boundaries in place, will
have to watch for the the threat of tornadoes. The main boundary
that will be the focus of storms through this evening into
tonight stretches from western South Dakota into the east-
central part of the state. As a shortwave embedded within the
otherwise zonal flow moves across the Northern Plains through
this evening, there should be an uptick in thunderstorm
development. The storms currently ongoing at the eastern end of
this boundary are going to continue to lift north and continue
to develop with westward extent as the shortwave encroaches the
area. The other concern with these storms will be the heavy rain
threat as areas near and north of Highway 14 already have
saturated grounds. This could lead to some flash flooding if
storms move too slowly over an area. And heavy rain to our north
may also cause some minor river flooding issues downstream
depending on how much rain is seen.

Another area of storms will develop off to our west. The best shear
is located over western South Dakota on the western end of the
main boundary. Guidance shows storms developing out there late
this afternoon/early evening may take on some bowing segments as
it moves eastward towards our area, arriving by 9-10 pm west of
the James River. This is where the best chance of damaging wind
gusts to 70 mph will be, though storms should gradually weaken
as they move eastward as instability wanes through the night. In
other words, after about midnight to 1 am, the severe weather
threat should come to an end. A few showers will be possible
heading into Friday morning, but nothing severe expected.
Another upper-wave moves across the northern Great Lakes region
tomorrow afternoon and evening, and this could set off some
isolated thunderstorms mainly near and east of I-29 and
especially towards the Highway 20 corridor. Can't rule out some
strong to severe thunderstorms with this activity, but this will
be highly dependent on how storms develop tonight. Also, the
greater instability will also be south of the area, likely
keeping the greatest threat to our south.

Ridging aloft builds in Saturday and so we should finally have a dry
day. This will be quickly replaced with another active upper pattern
heading into early next week, which will lead to increased shower
and storm chances Sunday and Monday. Just like the past few events,
ensembles show the instability sufficient for severe weather largely
in place, but there will be questions on how much shear there
will be with and of course any other mesoscale features that
can't be resolved this far out. Heat also looks to build in next
week, especially by Wednesday and Thursday when LREF
probabilities of highs exceeding 95 degrees are around 30-60%
near and west of the James River, with a 10-30% of highs even
exceeding 100 degrees in these areas. Recent rainfall may mean
that the forecast models could be overdoing potential heating,
but this will be something that needs to be watched closely over
the next couple of days.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 637 PM CDT Thu Jun 4 2026

Scattered showers and thunderstorms are ongoing at time of issuance.
Mainly along and north of Highway 14. These are expected to continue
through the evening. A second round of showers and thunderstorms are
possible after midnight into Friday morning. Some could be strong to
severe with large hail and wind gusts the primary threats.

Winds will become light and variable, allowing for patchy dense fog
formation. At times ceilings may degrade down to IFR, especially at
KSUX where fog looks to be thickest. Fog should burn off by mid-
morning. Skies gradually clear through the afternoon.

&&

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

&&

DISCUSSION...Samet
AVIATION...AJP

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
510 PM CDT Thu Jun 4 2026

MNZ071-072-080-081-097-SDZ038>040-050-052>065-068-052215-
Lincoln-Lyon-Murray-Cottonwood-Pipestone-Beadle-Kingsbury-Brookings-
Gregory-Jerauld-Sanborn-Miner-Lake-Moody-Brule-Aurora-Davison-Hanson-
McCook-Minnehaha-Charles Mix-Douglas-Hutchinson-Bon Homme-
510 PM CDT Thu Jun 4 2026

This Hazardous Weather Outlook is for southwest Minnesota, central
South Dakota, east central South Dakota, south central South Dakota
and southeast South Dakota.

.DAY ONE...Tonight.

Strong to severe thunderstorms have begun to form this afternoon
along and north of I-90. These storms will progress northeast over
the next few hours. A second round of strong to severe thunderstorms
is possible late this evening, forming over western South Dakota and
traveling east. The strongest storms may contain hail to ping pong
balls and wind gusts to 70 mph. Tornadoes are unlikely but cannot be
ruled out. Additionally, heavy rain will be possible with isolated
pockets of 1+ inches possible. Localized ponding is possible.

Storms are expected to weaken as they approach the I-29 corridor.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorm chances return for Friday afternoon and evening.
Though confidence is low, some could be strong to severe.

This weekend conditions will dry out and warm up into the 80s and
90s. Monday will be slightly cooler in the 80s. The first half of
next week will be hot, in the mid to upper 90s.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

IAZ001>003-012>014-020>022-031-032-MNZ089-090-098-NEZ013-014-SDZ066-
067-069>071-052215-
Lyon-Osceola-Dickinson-Sioux-O'Brien-Clay-Plymouth-Cherokee-
Buena Vista-Woodbury-Ida-Nobles-Jackson-Rock-Dixon-Dakota-Turner-
Lincoln-Yankton-Union-
510 PM CDT Thu Jun 4 2026

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

.DAY ONE...Tonight.

Scattered showers and thunderstorms will be possible into tonight.
While severe weather is not expected, an isolated storm could produce
hail to the size of half dollars and wind gusts to 60 mph.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Thunderstorm chances return for Friday afternoon and evening. Some
could be strong to severe.

This weekend conditions will dry out and warm up into the 80s and
90s. Monday will be slightly cooler in the 80s. The first half of
next week will be hot, in the mid to upper 90s.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
322 PM CDT Thu Jun 4 2026

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

0250 PM     Hail             5 WSW Bancroft          44.47N 97.84W
06/04/2026  M1.50 Inch       Kingsbury          SD   Trained Spotter

&&

JC

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
339 PM CDT Thu Jun 4 2026

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

0231 PM     Hail             Yale                    44.43N 97.99W
06/04/2026  M2.00 Inch       Beadle             SD   Trained Spotter

&&

JC

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
341 PM CDT Thu Jun 4 2026

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

0247 PM     Hail             6 WSW Bancroft          44.45N 97.86W
06/04/2026  M1.50 Inch       Beadle             SD   Public

&&

JC

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
402 PM CDT Thu Jun 4 2026

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

0239 PM     Hail             4 ENE Yale              44.46N 97.91W
06/04/2026  M2.75 Inch       Beadle             SD   Public

            Various hail size from golf ball to baseball
            via photo.

&&

JC

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