Alert archive / South Dakota / Dense Fog Advisories in 2021

Dense Fog Advisory 17, NWS Sioux Falls, SD

December 15, 202118 counties in South Dakota; 11 counties in Iowa; 8 counties in Minnesota

NWS Sioux Falls, SD issued this dense fog advisory at Dec 15, 2021, 2:56 AM CST for 18 counties in South Dakota; 11 counties in Iowa; 8 counties in Minnesota. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued: Dec 15, 2021, 2:56 AM CST (08:56 UTC)
Expired: Dec 15, 2021, 9:00 AM CST
In force: 6 hr
Issued by: NWS Sioux Falls, SD

All 37 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, Lincoln County, MN, Lyon County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Beadle County, SD, Bon Homme County, SD, Brookings County, SD, Clay County, SD, Davison County, SD, Hanson County, SD, Hutchinson County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 18 km from the middle of the area, began a volume at 09:01 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 00:00Z, 8.9 hours before the alert went out and 277 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 803 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 337 m²/s²
0-3 km storm-relative helicity: 309 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 dense fog advisory 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 dense fog advisory went out at Dec 14, 11:02 PM CST, 3 hours 54 minutes earlier.

Area forecast discussion, Dec 14, 11:02 PM CST, 3 hours 54 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, Dec 14, 4:15 PM CST, 10 hours 41 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>

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 15, 9:01 AM CST	Dense Fog Advisory	FSD	Beadle, Brookings, Davison, Hanson, Kingsbury, Lake and 4 more	119 min
Dec 15, 3:23 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Union	67 min
Dec 15, 4:00 PM CST	Tornado Warning	FSD	Union	45 min
Dec 15, 4:26 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Union	34 min
Dec 15, 4:05 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Buena Vista, Cherokee, Ida, Plymouth, Woodbury	55 min
Dec 15, 4:17 PM CST	Tornado Warning	FSD	Plymouth, Woodbury	28 min
Dec 15, 4:31 PM CST	Tornado Warning	FSD	Ida, Plymouth, Woodbury	29 min
Dec 15, 4:32 PM CST	Tornado Warning	FSD	Plymouth, Woodbury	28 min
Dec 15, 4:42 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay, Ida, O'Brien, Plymouth and 1 more	33 min
Dec 15, 4:51 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	O'Brien, Sioux	39 min
Dec 15, 4:56 PM CST	Severe Thunderstorm Warning Destructive damage threat	FSD	Buena Vista, Cherokee, Clay, Ida	46 min
Dec 15, 5:08 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay	37 min
Dec 15, 5:15 PM CST	Tornado Warning	FSD	Buena Vista, Cherokee, Clay, O'Brien	30 min
Dec 15, 5:29 PM CST	Severe Thunderstorm Warning Considerable damage threat	FSD	Dickinson	46 min

Nearby

Dense Fog Advisories in South Dakota, 2021 Dense Fog Advisories in Iowa, 2021 Dense Fog Advisories in Minnesota, 2021 Every dense fog advisory in 2021

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.