Alert archive / Nebraska / Mesoscale Discussions in 2007

Mesoscale Discussion 1838

August 21, 200712 counties in Iowa; 17 counties in Nebraska; 4 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 21, 2007, 6:17 PM CDT for 12 counties in Iowa; 17 counties in Nebraska; 4 counties in South Dakota. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued
Aug 21, 2007, 6:17 PM CDT (23:17 UTC)
Expired
Aug 21, 2007, 7:45 PM CDT
In force
88 min
Issued by
the Storm Prediction Center
All 33 counties

Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Sac County, IA, Sioux County, IA, Woodbury County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Greeley County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Platte County, NE, Stanton County, NE, Thurston County, NE, Wayne County, NE, Wheeler County, NE, Clay County, SD, Lincoln County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 140 km from the middle of the area, began a volume at 23:18 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.

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.3 hours before the alert went out and 140 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-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2007-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 174 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 12:00Z on 2007-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 46 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
174 J/kg
Mixed-layer CIN
-479 J/kg
Mixed-layer LCL
1438 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
46 m²/s²
0-3 km storm-relative helicity
61 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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.

IssuedProductOfficeCountiesLasted
Aug 20, 7:03 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Buena Vista, Calhoun, Carroll and 17 more117 min
Aug 20, 7:35 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Calhoun, Carroll, Cass and 15 more85 min
Aug 20, 8:10 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Audubon, Black Hawk, Boone and 50 more5 hr
Aug 20, 10:06 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Boone, Buena Vista, Calhoun and 43 more84 min
Aug 21, 4:50 PM CDTMesoscale DiscussionSPCDickinson, Emmet, Howard, Mitchell, Osceola, Winnebago and 1 more85 min
Aug 21, 6:47 PM CDTTornado WatchSPCAudubon, Black Hawk, Boone, Bremer, Buena Vista, Butler and 34 more7 hr
Aug 21, 2:47 PM CDTMesoscale DiscussionSPCAntelope, Blaine, Boone, Boyd, Brown, Buffalo and 44 more118 min
Aug 21, 3:45 PM CDTTornado WatchSPCAntelope, Boone, Boyd, Cedar, Colfax, Cuming and 14 more6 hr
Aug 21, 3:50 PM CDTSevere Thunderstorm WatchSPCAdams, Buffalo, Custer, Dawson, Franklin, Frontier and 16 more6 hr
Aug 21, 5:53 PM CDTMesoscale DiscussionSPCBuffalo, Dawson, Frontier, Furnas, Gosper, Harlan and 5 more97 min

Nearby

Mesoscale Discussions in Nebraska, 2007Mesoscale Discussions in Iowa, 2007Mesoscale Discussions in South Dakota, 2007Every mesoscale discussion in 2007

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.