Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 1377

August 28, 20184 states

The Storm Prediction Center issued this mesoscale discussion at Aug 28, 2018, 3:12 AM CDT for 4 states. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Aug 28, 2018, 3:12 AM CDT (08:12 UTC)
Expired: Aug 28, 2018, 5:45 AM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 5%

All 28 counties

Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Blue Earth County, MN, Cottonwood County, MN, Jackson County, MN, Martin County, MN, Nobles County, MN, Rock County, MN, Watonwan County, MN, Boyd County, NE, Cedar County, NE, Dixon County, NE, Holt County, NE, Knox County, NE, Bon Homme County, SD, Clay County, SD, Hutchinson County, SD, Lincoln County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 46 km from the middle of the area, began a volume at 08:14 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

Omaha, NE (KOAX), launched 00:00Z, 8.2 hours before the alert went out and 210 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: 2005 J/kg
Mixed-layer CIN: -82 J/kg
Mixed-layer LCL: 1801 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 155 m²/s²
0-3 km storm-relative helicity: 345 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 23.4

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
Aug 28, 7:50 AM CDT	Mesoscale Discussion	SPC	Allamakee, Black Hawk, Bremer, Butler, Cerro Gordo, Chickasaw and 15 more	115 min
Aug 28, 12:14 PM CDT	Mesoscale Discussion	SPC	Allamakee, Benton, Black Hawk, Boone, Bremer, Buchanan and 21 more	2 hr
Aug 28, 1:14 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Black Hawk, Bremer, Buchanan, Butler, Cerro Gordo and 18 more	8 hr
Aug 28, 4:45 PM CDT	Mesoscale Discussion	SPC	Appanoose, Cedar, Clarke, Davis, Decatur, Des Moines and 21 more	60 min
Aug 28, 5:06 PM CDT	Severe Thunderstorm Watch	SPC	Appanoose, Benton, Cedar, Clinton, Davis, Des Moines and 20 more	6 hr
Aug 28, 6:07 PM CDT	Mesoscale Discussion	SPC	Cedar, Iowa, Johnson, Keokuk, Muscatine, Washington	53 min
Aug 27, 9:07 PM CDT	Mesoscale Discussion	SPC	Aurora, Brule, Charles Mix, Davison, Douglas, Hanson and 1 more	83 min
Aug 27, 9:08 PM CDT	Mesoscale Discussion	SPC	Aurora, Brule, Charles Mix, Davison, Douglas, Hanson and 1 more	97 min

Nearby

Mesoscale Discussions in Iowa, 2018 Mesoscale Discussions in Minnesota, 2018 Mesoscale Discussions in South Dakota, 2018 Every mesoscale discussion in 2018

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.