Alert archive / Louisiana / Mesoscale Discussions in 2014

Mesoscale Discussion 425

April 27, 201418 parishes in Louisiana; 7 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2014, 4:21 PM CDT for 18 parishes in Louisiana; 7 counties in Mississippi. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Apr 27, 2014, 4:21 PM CDT (21:21 UTC)
Expired: Apr 27, 2014, 6:15 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 25 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Calcasieu Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberville Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Saint Martin Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Franklin County, MS, Jefferson County, MS, Lincoln County, MS, Pike County, MS, Wilkinson County, MS

The radar

The Ft Polk radar (KPOE), 112 km from the middle of the area, began a volume at 21:22 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

Lake Charles Mun, LA (KLCH), launched 12:00Z, 9.4 hours before the alert went out and 145 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: 1467 J/kg
Mixed-layer CIN: -224 J/kg
Mixed-layer LCL: 999 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 213 m²/s²
0-3 km storm-relative helicity: 265 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.1

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 27, 12:25 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Webster	2 hr
Apr 27, 1:46 PM CDT	Tornado Watch	SPC	Bossier, Caddo, Claiborne, Lincoln, Union, Webster	9 hr
Apr 27, 4:52 PM CDT	Mesoscale Discussion	SPC	Bossier, Claiborne, Webster	53 min
Apr 27, 6:11 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Webster	64 min
Apr 27, 6:05 AM CDT	Mesoscale Discussion	SPC	Attala, Bolivar, Calhoun, Carroll, Chickasaw, Choctaw and 36 more	55 min
Apr 27, 4:01 PM CDT	Mesoscale Discussion	SPC	Carroll, Choctaw, Coahoma, Grenada, Leflore, Montgomery and 3 more	89 min
Apr 27, 5:32 PM CDT	Tornado Watch	SPC	Calhoun, Chickasaw, Coahoma, DeSoto, Itawamba, Lafayette and 11 more	3 hr

Nearby

Mesoscale Discussions in Louisiana, 2014 Mesoscale Discussions in Mississippi, 2014 Every mesoscale discussion in 2014

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.