Alert archive / Arkansas / Mesoscale Discussions in 2009

Mesoscale Discussion 421

April 9, 20099 counties in Arkansas; Lincoln Parish, Morehouse Parish, Union Parish, Louisiana

The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2009, 11:47 PM CDT for 9 counties in Arkansas; Lincoln Parish, Morehouse Parish, Union Parish, Louisiana. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Apr 9, 2009, 11:47 PM CDT (04:47 UTC)
Expired: Apr 10, 2009, 12:45 AM CDT
In force: 58 min
Issued by: the Storm Prediction Center

Counties Arkansas County, AR, Ashley County, AR, Desha County, AR, Drew County, AR, Jefferson County, AR, Lincoln County, AR, Monroe County, AR, Prairie County, AR, Woodruff County, AR, Lincoln Parish, LA, Morehouse Parish, LA, Union Parish, LA

The radar

The Little Rock radar (KLZK), 147 km from the middle of the area, began a volume at 04:46 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

Shreveport, LA (KSHV), launched 00:00Z, 4.8 hours before the alert went out and 200 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: 938 J/kg
Mixed-layer CIN: -186 J/kg
Mixed-layer LCL: 814 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 370 m²/s²
0-3 km storm-relative helicity: 290 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 4.5

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 9, 7:21 PM CDT	Tornado Watch	SPC	Arkansas, Baxter, Boone, Bradley, Calhoun, Clark and 39 more	5 hr
Apr 9, 8:44 PM CDT	Mesoscale Discussion	SPC	Arkansas, Baxter, Boone, Bradley, Calhoun, Clark and 40 more	61 min
Apr 9, 9:10 PM CDT	Tornado Watch	SPC	Columbia, Hempstead, Howard, Lafayette, Little River, Miller and 3 more	4 hr
Apr 9, 9:43 PM CDT	Mesoscale Discussion	SPC	Arkansas, Ashley, Baxter, Bradley, Calhoun, Chicot and 51 more	2 hr
Apr 9, 10:48 PM CDT	Tornado Watch	SPC	Ashley, Chicot, Clay, Craighead, Crittenden, Cross and 8 more	4 hr
Apr 10, 1:24 AM CDT	Mesoscale Discussion	SPC	East Carroll, Madison	96 min

Nearby

Mesoscale Discussions in Arkansas, 2009 Mesoscale Discussions in Louisiana, 2009 Every mesoscale discussion in 2009

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.