Severe Thunderstorm Warning 150, NWS Sioux Falls, SD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1247 AM CDT Wed Jul 1 2026

.KEY MESSAGES...

- Above normal temperatures continue through the rest of this
  week and into the weekend, with humidity increasing daily.
  However, we'll remain below heat advisory levels.

- Severe weather risks develop after midnight bringing pockets
  of strong winds and severe hail into Wednesday morning. Some
  uncertainty lingers on coverage of strongest storms.

- An unsettled pattern continues into the holiday weekend with
  nearly daily risks for convection focused in the evening and
  overnight hours.

- Beyond Wednesday's evening isolated to scattered severe risks,
  concerns are growing for more widespread severe storms
  Thursday evening into Friday and again Friday into Saturday
  with one or more overnight storm complexes possible.

&&

.UPDATE...
Issued at 905 PM CDT Tue Jun 30 2026

The forecast for tonight remains on track. Moisture rich air
continues to flow into the region on southerly winds, pooling along
the south side of a quasi-stationary boundary. A compact shortwave
has begun to move out of the central Rockies onto the central
Plains. Convection initiation has begun over eastern Colorado and
western Kansas and Nebraska. This wave will move northeast through
the evening. As the wave pushes into south central South Dakota
around to shortly after midnight, the nose of the LLJ works to help
focus convection initiation along the boundary. As the wave
continues northeast it kicks the boundary into motion again and
convection will progress northeast with it. Updraft helicity tracks
continue to indicate potential for stronger rotating updrafts along
the leading edge of convection. Scattered severe thunderstorms
capable of producing large hail up to the size of ping-pong balls
and damaging wind gusts to 70 mph are possible with these.
Precipitable water is high (90-97th percentile per climatology) at 1
to 1.7 inches. With a deep warm cloud layer of over 14,000 ft AGL,
heavy rain will also be a risk with these storms. HREF ensemble
guidance indicates 0.25 to 0.5 inch per hour rainfall rates at
times. With heavier rainfall in the recent past, localized ponding
and urban roadway flooding may be possible. Risks for flash flooding
remain low at this time, but as always we will continue to monitor
rivers and streams for changes. Discrete supercells are expected to
gradually grow upscale into a QLCS. At this point threats for hail
will diminish and damaging wind gusts become the primary threat.
Gusts to 60-70 mph are possible with any stronger embedded cells.
With this round of storms, widespread rain of between roughly a
quarter of an inch up to an inch are possible, with highest amounts
targeted over the James River Valley east to I-29.

By roughly 6-8 am Wednesday morning storms will have pushed into
Minnesota. Some guidance has storms lingering there through part of
the day, while others have them clearing out with the wave. Storm
evolution from this point will have an impact on Wednesday evening's
chance for storms. Please see the Discussion below for further
details.

&&

.DISCUSSION...
Issued at 1247 PM CDT Tue Jun 30 2026

THIS AFTERNOON/EVENING:  Overnight storms have driven drier air
southeast into the CWA this afternoon, both at the surface but also
aloft.  Richer low-lvl theta-e airmass isn't too far away though
focused along Highway 20 into portions of southwestern Nebraska.
Therefore expect a continuation of quiet conditions, but still above
normal temperatures into this evening. One thing to note today is
the arrival of wildfire smoke through the region.  This smoke layer
is producing a milky sky, but also some minor downward mixing of
smoke to the surface creating air quality impacts.

TONIGHT:  Short term guidance continues to show a shortwave ejecting
out of the Central Rockies later this evening. The approach of
this wave will do two things. Firstly inducing a 40+ knot LLJ
through the Plains which will begin the northward advancement of
richer and more unstable air into the CWA after midnight.
Secondly, inducing convection across southwestern and southern
Nebraska by mid-evening. The approach of this wave will push
convection northward into the MO River valley after midnight,
with additional scattered convection forming on the advancing
elevated warm front further east into Iowa. Soundings do show an
increase in MUCAPE towards the 2000 J/KG mark ahead of this
wave. Anticipating some stronger wind gusts forming with
convection as it crosses Nebraska later this evening and any new
updraft on the leading edge of advancing low-lvl moisture could
produce some severe hail. The uncertainty tonight is just how
focused any stronger cluster development could become. Latest
HREF 2-5km updraft helicity plots suggest that at least a
narrow corridor through SE South Dakota into portions of the
Tri-State area could see some higher severe weather potential as
mid-lvl flow turns parallel to storm movement. That said, would
expect fairly widespread 30 to 50 mph wind gusts into the James
River valley, with potential for a more localized pocket or
more intense gusts that approach 70 mph with hail. The storm
risk will continue through 12Z into SW Minnesota where we'll
need to watch redeveloping updrafts try to form on the veering
LLJ.

WEDNESDAY: Morning convection could do one of two things. Completely
dissipate with the passage of the mid-lvl shortwave, or fester
deeper into the morning hours as the LLJ continues to converge into
SW Minnesota.  Lingering convection could continue a low end hail
risk.  A more likely scenario is that we see some stabilization
behind the departing wave with an EML beginning to build in by early
afternoon.  Guidance has backed off slightly on the potential for
widespread redevelopment in the afternoon and evening.  This is
likely due to a lack of a strong lifting mechanism, continued
lingering EML into the evening, and departure of mid-lvl jet.  The
nearby presence of mid-lvl vorticity across central and northern
South Dakota and potential of left over boundary from morning
convection, and then redevelopment of the evening LLJ will force at
least a 20-40% POP for convection by the evening into the overnight
hours mostly along and east of I-29 and north of Highway 14.  Given
instability and presence of sufficient remaining effective shear,
isolated to scattered supercells could be possible, potentially
merging into one or more eastward progressing clusters in the
late evening. This would be favored over portions of southern
Minnesota. Greatest concerns would be 2" hail but with
significant mid-lvl dry air and steep 0-2km lapse rates strong
winds would also be likely.

THURSDAY-FRIDAY: We'll stay in a highly unstable environment
for the end of the week and into the upcoming holiday weekend
the combination of the SERN ridge and western CONUS trough keeps
southwest to quasi-zonal flow through the Plains. This pattern
is one that will keep temperatures above normal, but also allow
dew points to remain in the upper 60s to lower 70s. The
combination will allow moderate to high instability to build
each afternoon and continue into the overnight. By Thursday
afternoon, we'll be keeping an eye on the development of a
stationary front lifting northward as a warm front in the
afternoon and evening. While and EML will be in place, any
subtle wave could trigger isolated to scattered strong
convection in the Tri-state area. Greater confidence however in
the development of severe convection on the western High Plains
and Black Hills region in the afternoon that would translate
east as a strong to severe forward propagating high wind
potential MCS into Friday morning.

We'll need to see how things play out Thursday into Friday to have a
strong handle on the severe potential that may develop Friday
evening and overnight.  Some guidance this morning hints at the
overnight MCS laying out a strong outflow boundary that could serve
as a focus for renewed severe convection Friday evening and
overnight.

4th of July:  Confidence lowers each day given the uncertainty in
the convective development the previous days.  That said, the
overall synoptic pattern remains problematic as a stationary
boundary linger in the area and the flattened mid-lvl flow brings
increased potential for daily shortwave activity eastward into the
Plains. Temperatures remain near to above normal with humid, but not
oppressive conditions favored.  Bottom line is anyone with outdoor
plans the 3rd and 4th needs to be aware of the forecast and the
storm potential that may develop.  Additionally, with the potential
for multiple MCS, there may be some concerns for excessive rainfall
in areas that see repeated convection.  Continue to monitor this
risk.

SUNDAY-MONDAY:  The synoptic pattern shifts by Sunday into next week
as mid-lvl ridging builds through the Plains. NBM probabilistic data
would suggest a fairly normal 25/75th spread for high temperatures
from the mid 80s to the lower 90s into early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1247 AM CDT Wed Jul 1 2026

Strong to severe thunderstorms are moving northeast out of Nebraska
and western Iowa. These storms look to enter into south central
South Dakota and northwestern Iowa roughly between 01.06-01.08Z.
Storms could produce very strong wind gusts to 70 mph, heavy rain,
and possibly large hail to the size of golf balls. Showers and
thunderstorms may linger into Wednesday afternoon, but the severe
threat should be over by around 01.12Z.

VFR conditions are expected to prevail for the period. Under
thunderstorms a brief period of MVFR to IFR is possible. Wednesday
afternoon southwest winds will be light to breezy with gusts to 22
kts possible for areas of northwest Iowa. Winds will become light
and variable toward the end of the period.

&&

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

&&

UPDATE...AJP
DISCUSSION...Dux
AVIATION...AJP

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
644 PM 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>071-012345-
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-
644 PM 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...Tonight.

A cluster of storms will develop in Nebraska later this evening and
lift north into the area, reaching northeast Nebraska, northwest Iowa
and the Missouri River around midnight to 1 am. Southeast South
Dakota and southwest Minnesota will see the better chances from about
2 am to 6 am. Wind gusts around 70 mph are possible as well as hail
to the size of golf balls. The stronger storms should diminish
between 4 to 6 am and lift northeast.

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

Severe thunderstorm chances continue Wednesday late afternoon through
late evening, 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 evolve.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed.

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
233 AM CDT Wed Jul 1 2026

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

0226 AM     Tstm Wnd Gst     2 NW Orange City        43.02N 96.08W
07/01/2026  E59 MPH          Sioux              IA   Public

            Davis personal weather station.

&&

SG

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
236 AM CDT Wed Jul 1 2026

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

0204 AM     Tstm Wnd Gst     1 WSW Fairfax           43.02N 98.91W
07/01/2026  M66 MPH          Gregory            SD   Public

            Personal weather station reported 66 mph
            wind gust at 2:04 am CDT.

&&

AJP

Preliminary Local Storm Report
National Weather Service Sioux Falls SD
241 AM CDT Wed Jul 1 2026

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

0223 AM     Tstm Wnd Gst     13 NE Burke             43.31N 99.10W
07/01/2026  E61 MPH          Gregory            SD   Public

            Personal weather station reported 61 mph
            wind gust at 2:23 am CDT.

&&

AJP