Alert archive / Mississippi / Mesoscale Discussions in 2018

Mesoscale Discussion 1746

December 31, 201820 parishes in Louisiana; 32 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Dec 31, 2018, 7:02 AM CST for 20 parishes in Louisiana; 32 counties in Mississippi. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: Dec 31, 2018, 7:02 AM CST (13:02 UTC)
Expired: Dec 31, 2018, 9:00 AM CST
In force: 118 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 52 counties

Allen Parish, LA, Avoyelles Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Helena Parish, LA, Tensas Parish, LA, Washington Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Choctaw County, MS, Claiborne County, MS, Copiah County, MS, Covington County, MS, Franklin County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Jefferson Davis County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Marion County, MS, Neshoba County, MS, Oktibbeha 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, Winston County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 135 km from the middle of the area, began a volume at 13:05 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

Jackson, MS (KJAN), launched 12:00Z, 1.0 hours before the alert went out and 130 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: 316 J/kg
Mixed-layer CIN: -25 J/kg
Mixed-layer LCL: 601 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 332 m²/s²
0-3 km storm-relative helicity: 423 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 2.5

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
Dec 31, 11:22 AM CST	Mesoscale Discussion	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 34 more	83 min
Dec 31, 11:47 AM CST	Tornado Watch	SPC	Alcorn, Attala, Benton, Calhoun, Chickasaw, Choctaw and 31 more	5 hr
Dec 31, 1:54 PM CST	Mesoscale Discussion	SPC	Clarke, Jasper, Kemper, Lauderdale, Lowndes, Monroe and 7 more	2 hr

Nearby

Mesoscale Discussions in Mississippi, 2018 Mesoscale Discussions in Louisiana, 2018 Every mesoscale discussion in 2018

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.