Flash Flood Warning 5, NWS Sioux Falls, SD

899 
WGUS73 KFSD 301152
FFSFSD

Flash Flood Statement
National Weather Service Sioux Falls SD
652 AM CDT Tue Jun 30 2026

IAC193-NEC043-301202-
/O.CAN.KFSD.FF.W.0005.000000T0000Z-260630T1230Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Woodbury IA-Dakota NE-
652 AM CDT Tue Jun 30 2026

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN WOODBURY AND
NORTHEASTERN DAKOTA COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please heed any local road closures. Report flooding to law
enforcement for relay to the National Weather Service.

&&

LAT...LON 4249 9647 4250 9647 4256 9642 4256 9631
      4242 9629 4243 9645 4248 9647 4249 9645

$$

JH

Area Forecast Discussion
National Weather Service Sioux Falls SD
428 AM CDT Tue Jun 30 2026

.KEY MESSAGES...

- Scattered showers and thunderstorms will continue through
  mid-Tuesday morning.

- Warm and humid today with highs in the 80s and 90s. Heat index
  values will climb into the mid to upper 90s. While no
  headlines are anticipated at this time, proper hydration and
  breaks out of the sun remain essential.

- An active pattern continues with chances for strong to severe
  thunderstorms nearly every evening/overnight for the rest of
  the week. Details remain uncertain as storms will depend on
  how the previous day's storms evolved.

&&

.UPDATE...
Issued at 421 AM CDT Tue Jun 30 2026

Another round of strong to severe thunderstorms are ongoing as of
4:00 am CDT. These are the result of a mid-level wave moving through
the region overnight. Increasing mid-level lapse rates ahead of the
wave in an already strongly unstable environment coupled with deep
layer shear of 40-50 kts result in an environment capable of
producing very strong wind gusts of 70-80 mph and heavy rainfall.
Large hail to the size of a ping-pong ball is also possible. Area
most at risk is along and east of I-29. Storms are expected to
continue through daybreak.

Tuesday should be a mostly sunny, lightly breezy day with highs in
the mid 80s to mid 90s. Dew point temperatures will be in the 50s
for southeast South Dakota and southwest Minnesota, and in the mid
60s to low 70s in northeast Nebraska and northwest Iowa. Apparent
temperatures will once again be warm in the low to mid 90s for most
of the region, but in the mid to upper 90s in northwest Iowa. Not
high enough or widespread enough to need a Heat Advisory, but still
enough that proper hydration and breaks out of the heat will be
necessary.

Throughout the day moisture rich air will flow north and pool along
a stationary front draped from south central Nebraska northeast into
the Arrowhead of northeast Minnesota. Steep mid-level lapse rates,
2000-3000 J/kg of MUCAPE, and 30-40 kts of deep layer shear will
work together to result in another environment capable of producing
strong to severe thunderstorms. SPC Day 1 Outlook includes a
Marginal Risk (level 1 of 5) for our CWA Tuesday evening into the
overnight. Similar to the past couple of days, a strong cap will be
in place. However, as the LLJ begins to ramp up in the mid to late
evening a few discrete super cells are possible in northeastern
Nebraska. With initial storm development large hail up to 1 to 1.5
inches are possible. One thing to note, the freezing level is
greater than 13,000 ft AGL. This may have an impact on hail size, as
it will have plenty of time to melt on the way down. Heavy rain and
damaging wind gusts are also possible. Storms are expected to become
elevated as they quickly grow upscale into a QLCS, possibly with
bowing segments. At this point the threats will transition to wind,
with 70 mph gusts possible. Storms will progress northeast through
the overnight into southwest Minnesota where they may linger through
about mid-day.

&&

.DISCUSSION...
Issued at 108 PM CDT Mon Jun 29 2026

Late this afternoon and Tonight:

An unstable environment will be in place today as a weak front works
into areas between about the James River and I-29 this afternoon.
This may be a focus for isolated thunderstorms as a weak wave begins
to move northeast from Nebraska ahead of the main wave to the west
of the area. CAPE values sitting around 3000 J/kg with the 0-3km and
0-6km shear values sitting about 30-40 knots. The questions for the
late afternoon and early evening activity will be getting enough
convergence to overcome the capping inversion. However, given these
parameters and a quick look at the model soundings showing a decent
amount of dry air below about 600mb, wind and heavy rain will be the
main threats. Wind gusts to 80 mph and locally heavy rain will be
the main threats. Hail to half dollar will be a threat as well.

Current thoughts are that there will likely be two areas of
convection to watch for. The first will be from roughly 6 pm to 9 pm
along the surface front and more driven by day time heating. This
will likely be near I-29 and is a bit lower confidence given a
strong capping inversion and weak low level convergence. The next,
increasingly more likely threat will be tied to a weak wave moving
out of Nebraska and an increasing LLJ. The better chances for this
will be from about 11 pm to 4 am and this is also when the threat
for the highest winds is expected.

Tuesday into Wednesday:

Tuesday should prove to be a fairly nice, albeit very warm, summer
day with lighter winds and dew points back into the 50s and 60s and
highs from the upper 80s to mid 90s. Currently do not anticipate any
heat headlines but parts of northwest Iowa do get close to a 100
heat index so there will be some potential at least.

Model output continues to point to Tuesday night into Wednesday as a
period with a good chance for showers and thunderstorms. A wave will
rotate northeast through Nebraska and bring a strong increase in the
LLJ into southern SD by about 6z and northwest IA and southwest MN
shortly after. Given the shear profile and expected instability
around 2500 J/kg, a few severe storms will be possible. The low
level remain fairly dry so given the amount of instability we may
see some potential for 75 to 80 mph winds as well as pin pong ball
sized hail.

Wednesday afternoon and evening may see some scattered showers and
storms with the better chances in northwest IA as a front lingers
after the likely morning showers and storms. With the threat for
clouds and a post outflow air mass, heat headlines are again not
expected.

Thursday into the weekend:

The next good chance for showers and thunderstorms moves in Thursday
into Thursday night as another well agreed upon wave moves through.
Will likely continue the threat for locally heavy rain and isolated
severe thunderstorms depending upon where any outflow boundaries end
up.

Friday into the weekend continues the trends of near daily waves as
the upper level flow transitions to a bit more westerly direction.
This hints at a chance for showers and storms Friday and Saturday
with a potential break by Sunday into Monday as a weak ridge aloft
builds in. For now this time frame is pretty low confidence given
all of the activity tonight through Thursday night.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1219 AM CDT Tue Jun 30 2026

An earlier line of storms over NW IA/SW MN late this evening
will be followed by another round of thunderstorms lifting from
the southwest overnight, impacting SUX 6-9Z and FSD 7-10Z.
Confidence is currently low that storms will extend as far
northwest as HON. High pressure builds over the region behind
the storms Wednesday resulting in light and variable winds.
Outside of thunderstorms, VFR conditions will prevail through
the period.

&&

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

&&

UPDATE...AJP
DISCUSSION...08
AVIATION...AJP

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
432 AM CDT Tue Jun 30 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-010945-
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-
432 AM CDT Tue Jun 30 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.

Scattered showers and thunderstorms will continue through about mid-
Tuesday morning.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Strong to severe thunderstorms are possible Tuesday night. Primary
hazards include large hail, heavy downpours, and damaging wind gusts.
Storms may linger over southwest Minnesota through mid-day Wednesday.

Severe chances continue Wednesday night, but will depend on how long
showers hang around during the day.

Storm chances continue nearly every night for the rest of the week.
Uncertainty is high as each night's storms will depend on how the
previous day's storms evolved.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
251 AM CDT Tue Jun 30 2026

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

0234 AM     Tstm Wnd Gst     3 WNW Spencer           43.17N 95.21W
06/30/2026  M66 MPH          Clay               IA   ASOS

            Automated Equipment at Spencer Airport.

&&

JH

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
307 AM CDT Tue Jun 30 2026

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

0248 AM     Tstm Wnd Gst     1 NNE Jackson           43.64N 94.98W
06/30/2026  M58 MPH          Jackson            MN   Public

            Davis Personal Weather Station.

0250 AM     Tstm Wnd Gst     4 SE Lakefield          43.64N 95.12W
06/30/2026  M62 MPH          Jackson            MN   Mesonet

            Mesonet station MN008 I-90 - Lakefield - Mp
            67.

0255 AM     Tstm Wnd Gst     1 ENE Jackson           43.63N 94.97W
06/30/2026  M73 MPH          Jackson            MN   AWOS

            AWOS station KMJQ Jackson Airport.

0259 AM     Tstm Wnd Gst     2 SW Bergen             43.77N 95.02W
06/30/2026  M71 MPH          Jackson            MN   Public

            Davis Personal Weather Station.

&&

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
324 AM CDT Tue Jun 30 2026

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

0304 AM     Tstm Wnd Gst     2 S Mountain Lake       43.91N 94.92W
06/30/2026  M63 MPH          Cottonwood         MN   Public

            Ambient Personal Weather Station.

0308 AM     Tstm Wnd Gst     3 SSE Mountain Lake     43.89N 94.91W
06/30/2026  M71 MPH          Cottonwood         MN   Public

            Ambient Personal Weather Station.

0309 AM     Tstm Wnd Gst     2 W Mountain Lake       43.94N 94.97W
06/30/2026  M62 MPH          Cottonwood         MN   Public

            Davis Personal Weather Station.

0310 AM     Tstm Wnd Gst     2 ENE Bingham Lake      43.92N 95.00W
06/30/2026  M76 MPH          Cottonwood         MN   Mesonet

            Mesonet station MN150 T.h.60 - Mountain Lake
            - Mp 48.

0310 AM     Tstm Wnd Gst     4 NNW Bergen            43.84N 95.03W
06/30/2026  E67 MPH          Jackson            MN   Mesonet

            NDAWN Station.

&&

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
325 AM CDT Tue Jun 30 2026

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

0240 AM     Tstm Wnd Gst     1 NNE Orleans           43.46N 95.09W
06/30/2026  E74 MPH          Dickinson          IA   Public

            Ambient Personal Weather Station.

&&

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
356 AM CDT Tue Jun 30 2026

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

0235 AM     Tstm Wnd Dmg     Lake Park               43.45N 95.32W
06/30/2026                   Dickinson          IA   Emergency Mngr

            Grain leg down on power lines and numerous
            branches down on city streets in Lake Park.
            Also tree damage to a camper and truck on
            the south side of Silver Lake. No injuries.

0306 AM     Tstm Wnd Dmg     1 NW Bergen             43.80N 95.01W
06/30/2026                   Jackson            MN   Emergency Mngr

            Lots of tree damage and possibly some
            structural damage to house. Will assess
            further in daylight.

&&

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
429 AM CDT Tue Jun 30 2026

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

0130 AM     Hail             2 SE Sioux City         42.49N 96.37W
06/30/2026  M1.00 Inch       Woodbury           IA   Trained Spotter

0131 AM     Hail             2 E South Sioux City    42.47N 96.37W
06/30/2026  M1.00 Inch       Woodbury           IA   Public

0135 AM     Hail             4 SSE Sioux City        42.46N 96.36W
06/30/2026  M1.25 Inch       Woodbury           IA   Public

            Relayed through Broadcast Media with photo.

&&
Delayed Reports from earlier this morning.