Alert archive / Mississippi / Mesoscale Discussions in 2013

Mesoscale Discussion 526

April 18, 201318 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2013, 6:52 PM CDT for 18 counties in Mississippi. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued: Apr 18, 2013, 6:52 PM CDT (23:52 UTC)
Expired: Apr 18, 2013, 8:15 PM CDT
In force: 83 min
Issued by: the Storm Prediction Center

Counties Attala County, MS, Calhoun County, MS, Carroll County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Grenada County, MS, Holmes County, MS, Leake County, MS, Madison County, MS, Montgomery County, MS, Neshoba County, MS, Oktibbeha County, MS, Pontotoc County, MS, Webster County, MS, Winston County, MS, Yalobusha County, MS, Yazoo County, MS

The radar

The Columbus AFB radar (KGWX), 119 km from the middle of the area, began a volume at 23:55 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

Jackson, MS (KJAN), launched 12:00Z, 11.9 hours before the alert went out and 135 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: 73 J/kg
Mixed-layer CIN: -438 J/kg
Mixed-layer LCL: 606 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 228 m²/s²
0-3 km storm-relative helicity: 351 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.

Issued	Product	Office	Counties	Lasted
Apr 18, 12:48 PM CDT	Mesoscale Discussion	SPC	Benton, Bolivar, Coahoma, DeSoto, Grenada, Humphreys and 13 more	87 min
Apr 18, 1:43 PM CDT	Tornado Watch	SPC	Adams, Attala, Bolivar, Carroll, Choctaw, Claiborne and 28 more	8 hr
Apr 18, 4:56 PM CDT	Mesoscale Discussion	SPC	Attala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 27 more	94 min
Apr 18, 5:52 PM CDT	Tornado Watch	SPC	Calhoun, Chickasaw, Itawamba, Lafayette, Lee, Monroe and 6 more	5 hr

Nearby

Mesoscale Discussions in Mississippi, 2013 Every mesoscale discussion in 2013

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.