Alert archive / Louisiana / Mesoscale Discussions in 2017

Mesoscale Discussion 544

April 22, 20174 states

The Storm Prediction Center issued this mesoscale discussion at Apr 22, 2017, 4:16 AM CDT for 4 states. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued: Apr 22, 2017, 4:16 AM CDT (09:16 UTC)
Expired: Apr 22, 2017, 5:45 AM CDT
In force: 89 min
Issued by: the Storm Prediction Center

All 34 counties

Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Columbia County, AR, Desha County, AR, Drew County, AR, Ouachita County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Bolivar County, MS, Sunflower County, MS, Washington County, MS, Angelina County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, San Augustine County, TX, Shelby County, TX

The radar

The Shreveport radar (KSHV), 85 km from the middle of the area, began a volume at 09:20 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 (KBAD), launched 00:00Z, 9.3 hours before the alert went out and 76 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: 828 J/kg
Mixed-layer CIN: -29 J/kg
Mixed-layer LCL: 1486 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 143 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 4.5

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, 7:11 PM CDT	Mesoscale Discussion	SPC	Howard, Little River, Montgomery, Pike, Polk, Scott and 3 more	94 min
Apr 21, 9:28 PM CDT	Mesoscale Discussion	SPC	Garland, Hempstead, Howard, Little River, Miller, Montgomery and 5 more	92 min
Apr 21, 11:39 PM CDT	Mesoscale Discussion	SPC	Calhoun, Clark, Columbia, Dallas, Garland, Hempstead and 13 more	96 min
Apr 22, 12:41 AM CDT	Severe Thunderstorm Watch	SPC	Arkansas, Ashley, Bradley, Calhoun, Chicot, Clark and 22 more	6 hr
Apr 22, 12:51 PM CDT	Mesoscale Discussion	SPC	Chicot	114 min
Apr 22, 4:56 PM CDT	Mesoscale Discussion	SPC	Madison, Tensas	64 min
Apr 22, 3:08 PM CDT	Severe Thunderstorm Watch	SPC	Attala, Carroll, Chickasaw, Choctaw, Clay, Holmes and 16 more	4 hr

Nearby

Mesoscale Discussions in Louisiana, 2017 Mesoscale Discussions in Arkansas, 2017 Mesoscale Discussions in Texas, 2017 Every mesoscale discussion in 2017

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.