Alert archive / Louisiana / Mesoscale Discussions in 2009

Mesoscale Discussion 699

May 4, 20094 states

The Storm Prediction Center issued this mesoscale discussion at May 4, 2009, 1:34 PM CDT for 4 states. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: May 4, 2009, 1:34 PM CDT (18:34 UTC)
Expired: May 4, 2009, 2:30 PM CDT
In force: 56 min
Issued by: the Storm Prediction Center

All 33 counties

Baldwin County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Mobile County, AL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Ascension Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, George County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Pearl River County, MS, Stone County, MS

The radar

The Mobile radar (KMOB), 58 km from the middle of the area, began a volume at 18:35 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

Slidell Radar S, LA (KSIL), launched 12:00Z, 6.6 hours before the alert went out and 92 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: 2102 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 577 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 170 m²/s²
0-3 km storm-relative helicity: 242 m²/s²
Significant tornado parameter: 1.6
Supercell composite: 9.9

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
May 4, 1:30 AM CDT	Mesoscale Discussion	SPC	Barbour, Bullock, Butler, Choctaw, Clarke, Coffee and 13 more	3 hr
May 4, 2:12 AM CDT	Mesoscale Discussion	SPC	Baldwin, Coffee, Covington, Dale, Escambia, Geneva and 2 more	93 min
May 4, 2:34 AM CDT	Tornado Watch	SPC	Baldwin, Butler, Clarke, Conecuh, Covington, Crenshaw and 5 more	5 hr
May 4, 4:58 AM CDT	Mesoscale Discussion	SPC	Baldwin, Barbour, Butler, Clarke, Coffee, Conecuh and 10 more	2 hr
May 4, 7:33 AM CDT	Tornado Watch	SPC	Baldwin, Butler, Coffee, Conecuh, Covington, Crenshaw and 6 more	6 hr
May 4, 10:38 AM CDT	Mesoscale Discussion	SPC	Barbour, Dale, Geneva, Henry, Houston	67 min
May 4, 3:24 PM CDT	Mesoscale Discussion	SPC	Bibb, Chilton, Choctaw, Clarke, Clay, Coosa and 7 more	66 min
May 4, 12:02 PM CDT	Severe Thunderstorm Watch	SPC	Baker, Columbia, Gadsden, Hamilton, Jefferson, Leon and 4 more	7 hr

Nearby

Mesoscale Discussions in Louisiana, 2009 Mesoscale Discussions in Alabama, 2009 Mesoscale Discussions in Florida, 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; radar from the NEXRAD Level II archive.