Alert archive / Iowa / Mesoscale Discussions in 2004

Mesoscale Discussion 381

April 18, 20044 states

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2004, 11:12 PM CDT for 4 states. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2004, 11:12 PM CDT (04:12 UTC)
Expired: Apr 19, 2004, 12:45 AM CDT
In force: 93 min
Issued by: the Storm Prediction Center

All 81 counties

Adair County, IA, Adams County, IA, Allamakee County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clarke County, IA, Clayton County, IA, Dallas County, IA, Delaware County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Fremont County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Howard County, IA, Humboldt County, IA, Jasper County, IA, Madison County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Mitchell County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Webster County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Fillmore County, MN, Houston County, MN, Mower County, MN, Olmsted County, MN, Wabasha County, MN, Winona County, MN, Cass County, NE, Douglas County, NE, Lancaster County, NE, Sarpy County, NE, Adams County, WI, Buffalo County, WI, Crawford County, WI, Jackson County, WI, Juneau County, WI, La Crosse County, WI, Marquette County, WI, Monroe County, WI, Outagamie County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Trempealeau County, WI, Vernon County, WI, Waupaca County, WI, Waushara County, WI, Wood County, WI

The radar

The Des Moines radar (KDMX), 90 km from the middle of the area, began a volume at 04:12 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, 4.2 hours before the alert went out and 289 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: 671 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 2341 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 244 m²/s²
0-3 km storm-relative helicity: 328 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

<!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
Apr 18, 7:05 PM CDT	Mesoscale Discussion	SPC	Audubon, Buena Vista, Calhoun, Carroll, Cass, Cherokee and 29 more	115 min
Apr 18, 9:45 PM CDT	Tornado Watch	SPC	Adair, Adams, Allamakee, Audubon, Benton, Black Hawk and 49 more	4 hr
Apr 18, 7:10 PM CDT	Mesoscale Discussion	SPC	Lincoln, Pipestone, Rock	65 min
Apr 18, 8:28 PM CDT	Mesoscale Discussion	SPC	Brown, Carver, Dakota, Goodhue, Hennepin, Le Sueur and 7 more	92 min
Apr 18, 8:45 PM CDT	Severe Thunderstorm Watch	SPC	Langlade, Marinette	4 hr

Nearby

Mesoscale Discussions in Iowa, 2004 Mesoscale Discussions in Wisconsin, 2004 Mesoscale Discussions in Minnesota, 2004 Every mesoscale discussion in 2004

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.