Alert archive / Oklahoma / Mesoscale Discussions in 2020

Mesoscale Discussion 428

April 21, 202019 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2020, 6:17 PM CDT for 19 counties in Oklahoma. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Apr 21, 2020, 6:17 PM CDT (23:17 UTC)
Expired: Apr 21, 2020, 7:15 PM CDT
In force: 58 min
Issued by: the Storm Prediction Center
Chance of a watch: 95%

Counties Beckham County, OK, Blaine County, OK, Caddo County, OK, Canadian County, OK, Cleveland County, OK, Comanche County, OK, Custer County, OK, Dewey County, OK, Garvin County, OK, Grady County, OK, Greer County, OK, Kiowa County, OK, McClain County, OK, Murray County, OK, Oklahoma County, OK, Pottawatomie County, OK, Roger Mills County, OK, Stephens County, OK, Washita County, OK

The radar

The Norman radar (KTLX), 108 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.

Severe Thunderstorm Watch 130Apr 21, 6:50 PM CDT

The nearest sounding before it

Dodge City, (KDDC), launched 12:00Z, 11.3 hours before the alert went out and 295 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: 2524 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 103 m²/s²
0-3 km storm-relative helicity: 97 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Apr 21, 2:17 PM CDT	Mesoscale Discussion	SPC	Cimarron, Texas	58 min
Apr 21, 3:11 PM CDT	Severe Thunderstorm Watch	SPC	Beaver, Cimarron, Texas	6 hr
Apr 21, 5:27 PM CDT	Mesoscale Discussion	SPC	Beaver, Beckham, Cimarron, Ellis, Greer, Harmon and 2 more	93 min
Apr 21, 6:50 PM CDT	Severe Thunderstorm Watch	SPC	Beckham, Blaine, Caddo, Canadian, Carter, Cleveland and 23 more	7 hr

Nearby

Mesoscale Discussions in Oklahoma, 2020 Every mesoscale discussion in 2020

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.