Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 308

March 27, 200938 parishes in Louisiana; 35 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2009, 11:06 PM CDT for 38 parishes in Louisiana; 35 counties in Mississippi. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: Mar 27, 2009, 11:06 PM CDT (04:06 UTC)
Expired: Mar 28, 2009, 12:30 AM CDT
In force: 84 min
Issued by: the Storm Prediction Center

All 73 counties

Acadia Parish, LA, Allen Parish, LA, Ascension Parish, LA, Assumption Parish, LA, Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Lafourche Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, Saint Tammany Parish, LA, St. Mary Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, Hinds County, MS, Issaquena 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, Neshoba County, MS, Newton County, MS, Pearl River County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS

The watches that followed

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

Tornado Watch 86Mar 28, 2:15 AM CDT

The nearest sounding before it

Jackson, MS (KJAN), launched 00:00Z, 4.1 hours before the alert went out and 136 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: 602 J/kg
Mixed-layer CIN: -31 J/kg
Mixed-layer LCL: 1068 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 66 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 5.7

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
Mar 27, 7:51 PM CDT	Tornado Watch	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Calcasieu and 36 more	9 hr
Mar 27, 8:21 PM CDT	Mesoscale Discussion	SPC	Orleans, Saint Bernard, Saint Tammany, Washington	84 min
Mar 27, 10:24 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, East Carroll and 13 more	96 min
Mar 27, 11:51 PM CDT	Mesoscale Discussion	SPC	Saint Bernard	84 min
Mar 28, 1:33 AM CDT	Mesoscale Discussion	SPC	Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 14 more	27 min
Mar 28, 4:25 AM CDT	Mesoscale Discussion	SPC	Saint Bernard, Saint Tammany	35 min
Mar 27, 10:09 PM CDT	Tornado Watch	SPC	George, Greene, Hancock, Harrison, Jackson, Perry and 2 more	9 hr
Mar 28, 2:20 AM CDT	Tornado Watch	SPC	Clarke, Covington, Forrest, Jasper, Jefferson Davis, Jones and 10 more	3 hr
Mar 28, 3:14 AM CDT	Mesoscale Discussion	SPC	George, Greene, Harrison, Jackson, Perry, Stone and 1 more	61 min
Mar 28, 4:50 AM CDT	Tornado Watch	SPC	George, Greene, Perry, Stone, Wayne	5 hr

Nearby

Mesoscale Discussions in Louisiana, 2009 Mesoscale Discussions in Mississippi, 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.