Alert archive / Iowa / Flood Watches in 2026

Flood Watch 2, NWS Sioux Falls, SD

September 6, 2026Lincoln County, Minnehaha County, Union County, South Dakota; 11 counties in Iowa; 6 counties in Minnesota

NWS Sioux Falls, SD issued this flood watch at Sep 6, 2026, 10:23 AM CDT for Lincoln County, Minnehaha County, Union County, South Dakota; 11 counties in Iowa; 6 counties in Minnesota. It was in force for 9 hr.

The area

The counties it named.

The facts

Issued: Sep 6, 2026, 10:23 AM CDT (15:23 UTC)
Expired: Sep 6, 2026, 7:23 PM CDT
In force: 9 hr
Issued by: NWS Sioux Falls, SD
Flood severity: None

Counties Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Ida County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Cottonwood County, MN, Jackson County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Lincoln County, SD, Minnehaha County, SD, Union County, SD

The radar

The Sioux Falls radar (KFSD), 80 km from the middle of the area, began a volume at 15:23 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 nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 3.4 hours before the alert went out and 252 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: 257 J/kg
Mixed-layer CIN: -330 J/kg
Mixed-layer LCL: 1056 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 55 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flood watch went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Sioux Falls, SD wrote its last area forecast discussion before this flood watch went out at Sep 6, 6:36 AM CDT, 3 hours 47 minutes earlier.

Area forecast discussion, Sep 6, 6:36 AM CDT, 3 hours 47 minutes before

<!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>

Hazardous weather outlook, Sep 6, 3:47 AM CDT, 6 hours 36 minutes before

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
347 AM CDT Sun Sep 6 2026

IAZ001>003-012>014-020>022-031-032-MNZ071-072-080-081-089-090-097-
098-NEZ013-014-SDZ038>040-050-052>071-070900-
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-
347 AM CDT Sun Sep 6 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.

Patchy fog may reduce visibility below a mile east of I-29 this
morning.

Thunderstorms return to the area by late morning, continuing through
the late afternoon and evening. Isolated strong storms may produce
hail to the size of a ping pong ball and wind gusts to 65 mph.

Locally heavy rainfall is possible Sunday with isolated totals of 2
to 4 inches. Some locations with multiple rounds of thunderstorms
may exceed 4 inches of rainfall through this evening.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Hot and humid again for Monday with Heat Index values in the 90s to
near 100 for areas along the southern Missouri River Valley.

Periodic storm chances continue into the middle part of the week.
Isolated severe storms and locally heavy rainfall possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed Sunday and again at times early
next week.

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 6, 2:07 PM CDT	Flash Flood Warning	FSD	Brookings, Minnehaha, Moody	4 hr
Sep 6, 11:58 AM CDT	Flash Flood Warning	FSD	Lyon, Osceola	4 hr
Sep 6, 2:11 PM CDT	Flash Flood Warning	FSD	Cherokee	4 hr
Sep 6, 2:34 PM CDT	Severe Thunderstorm Warning	FSD	Buena Vista, Cherokee, Ida	41 min

Nearby

Flood Watches in Iowa, 2026 Flood Watches in Minnesota, 2026 Flood Watches in South Dakota, 2026 Every flood watch in 2026

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.