Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 737

May 11, 201119 counties in Iowa; 14 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 11, 2011, 2:31 PM CDT for 19 counties in Iowa; 14 counties in Nebraska. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 11, 2011, 2:31 PM CDT (19:31 UTC)
Expired: May 11, 2011, 3:30 PM CDT
In force: 59 min
Issued by: the Storm Prediction Center

All 33 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Carroll County, IA, Cass County, IA, Crawford County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Harrison County, IA, Ida County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Woodbury County, IA, Burt County, NE, Butler County, NE, Cass County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dodge County, NE, Douglas County, NE, Lancaster County, NE, Sarpy County, NE, Saunders County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 62 km from the middle of the area, began a volume at 19:33 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.

Tornado Watch 282May 11, 2:55 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 7.5 hours before the alert went out and 62 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: 909 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 1123 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 177 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.2

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
May 10, 8:45 PM CDT	Mesoscale Discussion	SPC	Allamakee, Howard, Mitchell, Winneshiek, Worth	90 min
May 11, 8:09 AM CDT	Mesoscale Discussion	SPC	Allamakee, Appanoose, Benton, Black Hawk, Bremer, Buchanan and 32 more	66 min
May 11, 1:23 PM CDT	Severe Thunderstorm Watch	SPC	Allamakee, Benton, Buchanan, Cedar, Clayton, Clinton and 17 more	6 hr
May 11, 2:53 PM CDT	Tornado Watch	SPC	Adair, Adams, Appanoose, Audubon, Boone, Carroll and 33 more	6 hr
May 11, 3:38 PM CDT	Mesoscale Discussion	SPC	Allamakee, Appanoose, Benton, Black Hawk, Buchanan, Cedar and 26 more	2 hr
May 11, 5:03 PM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more	57 min
May 11, 6:17 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Davis, Decatur, Jasper, Lucas and 9 more	28 min
May 11, 12:16 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Buffalo, Butler, Cass, Clay, Colfax and 37 more	5 hr
May 11, 3:57 PM CDT	Mesoscale Discussion	SPC	Nemaha, Pawnee, Richardson	48 min
May 11, 4:52 PM CDT	Tornado Watch	SPC	Dundy, Furnas, Harlan, Hitchcock, Red Willow	6 hr

Nearby

Mesoscale Discussions in Iowa, 2011 Mesoscale Discussions in Nebraska, 2011 Every mesoscale discussion in 2011

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.