Alert archive / South Dakota / Mesoscale Discussions in 2025

Mesoscale Discussion 1839

July 29, 20258 counties in Iowa; 7 counties in Nebraska; 10 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 29, 2025, 7:30 PM CDT for 8 counties in Iowa; 7 counties in Nebraska; 10 counties in South Dakota. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued: Jul 29, 2025, 7:30 PM CDT (00:30 UTC)
Expired: Jul 29, 2025, 9:00 PM CDT
In force: 90 min
Issued by: the Storm Prediction Center
Concerning: Severe thunderstorm watch 557

All 25 counties

Cherokee County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cedar County, NE, Dakota County, NE, Dixon County, NE, Knox County, NE, Pierce County, NE, Thurston County, NE, Wayne County, NE, Bon Homme County, SD, Clay County, SD, Hanson County, SD, Hutchinson County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 91 km from the middle of the area, began a volume at 00:30 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 559Jul 29, 8:25 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.5 hours before the alert went out and 166 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 5070 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 1351 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 10 m²/s²
0-3 km storm-relative helicity: 74 m²/s²
Significant tornado parameter: 1.4
Supercell composite: 14.2

Open this sounding in Storm Lab

The text

As transmitted.

<!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>

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 8:24 PM CDT	Severe Thunderstorm Watch	SPC	Audubon, Buena Vista, Calhoun, Carroll, Cherokee, Clay and 16 more	6 hr
Jul 29, 9:26 PM CDT	Mesoscale Discussion	SPC	Audubon, Buena Vista, Calhoun, Carroll, Cass, Cherokee and 14 more	94 min
Jul 29, 9:48 PM CDT	Severe Thunderstorm Watch	SPC	Fremont, Mills, Montgomery, Page, Pottawattamie	5 hr
Jul 29, 11:55 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Calhoun, Carroll, Cass and 14 more	2 hr
Jul 30, 1:23 AM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Black Hawk, Boone, Cass and 24 more	5 hr
Jul 30, 1:28 AM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Benton, Boone, Buchanan and 43 more	2 hr
Jul 30, 4:49 AM CDT	Mesoscale Discussion	SPC	Appanoose, Davis, Des Moines, Henry, Iowa, Jefferson and 10 more	56 min
Jul 29, 7:08 PM CDT	Severe Thunderstorm Watch	SPC	Box Butte, Dawes, Scotts Bluff, Sioux	6 hr
Jul 29, 8:36 PM CDT	Mesoscale Discussion	SPC	Adams, Boone, Buffalo, Butler, Cass, Clay and 29 more	84 min
Jul 29, 9:43 PM CDT	Mesoscale Discussion	SPC	Butte, Custer, Lawrence, Meade, Pennington	2 hr

Nearby

Mesoscale Discussions in South Dakota, 2025 Mesoscale Discussions in Iowa, 2025 Mesoscale Discussions in Nebraska, 2025 Every mesoscale discussion in 2025

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.