Alert archive / Louisiana / Mesoscale Discussions in 2017

Mesoscale Discussion 93

January 21, 201722 parishes in Louisiana; 21 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Jan 21, 2017, 2:34 PM CST for 22 parishes in Louisiana; 21 counties in Mississippi. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 21, 2017, 2:34 PM CST (20:34 UTC)
Expired: Jan 21, 2017, 5:00 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 43 counties

Allen Parish, LA, Ascension Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberville Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Vernon Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wilkinson County, MS

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 8.6 hours before the alert went out and 126 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: 1327 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 508 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 275 m²/s²
0-3 km storm-relative helicity: 323 m²/s²
Significant tornado parameter: 2.4
Supercell composite: 11.2

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
Jan 20, 6:37 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 3 more	113 min
Jan 20, 7:32 PM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 9 more	6 hr
Jan 20, 10:04 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Calcasieu, Cameron, Evangeline and 7 more	116 min
Jan 20, 10:44 PM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more	61 min
Jan 20, 11:00 PM CST	Tornado Watch	SPC	Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberville and 17 more	8 hr
Jan 21, 1:41 AM CST	Mesoscale Discussion	SPC	Acadia, Avoyelles, Cameron, Evangeline, Iberia, Jefferson Davis and 5 more	64 min
Jan 21, 2:55 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more	2 hr
Jan 21, 6:35 AM CST	Mesoscale Discussion	SPC	Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 1 more	55 min
Jan 21, 2:33 PM CST	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more	2 hr
Jan 21, 3:29 PM CST	Tornado Watch	SPC	Acadia, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 22 more	6 hr
Jan 21, 3:41 PM CST	Tornado Watch	SPC	Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more	7 hr
Jan 21, 5:32 PM CST	Mesoscale Discussion	SPC	Avoyelles, Bienville, Bossier, Caddo, Caldwell, Catahoula and 23 more	118 min

Nearby

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