Alert archive / Mississippi / Mesoscale Discussions in 2017

Mesoscale Discussion 709

May 12, 201718 parishes in Louisiana; 45 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 12, 2017, 1:43 PM CDT for 18 parishes in Louisiana; 45 counties in Mississippi. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: May 12, 2017, 1:43 PM CDT (18:43 UTC)
Expired: May 12, 2017, 4:15 PM CDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 63 counties

Ascension Parish, LA, Assumption Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Carroll County, MS, Choctaw County, MS, Claiborne County, MS, Clarke County, MS, Clay County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Oktibbeha County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Warren County, MS, Webster County, MS, Wilkinson County, MS, Winston County, MS, Yazoo County, MS

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 6.7 hours before the alert went out and 127 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: 550 J/kg
Mixed-layer CIN: -11 J/kg
Mixed-layer LCL: 685 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 8 m²/s²
0-3 km storm-relative helicity: 14 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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
May 12, 4:24 AM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 4 more	3 hr
May 12, 9:56 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, Jefferson, Lafourche, Livingston, Orleans and 8 more	3 hr
May 12, 10:35 AM CDT	Severe Thunderstorm Watch	SPC	Assumption, Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard and 5 more	5 hr
May 12, 10:59 AM CDT	Mesoscale Discussion	SPC	Morehouse, West Carroll	3 hr
May 12, 1:42 PM CDT	Mesoscale Discussion	SPC	Saint Bernard	108 min

Nearby

Mesoscale Discussions in Mississippi, 2017 Mesoscale Discussions in Louisiana, 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.