Alert archive / North Carolina / Mesoscale Discussions in 2018

Mesoscale Discussion 266

April 15, 201817 counties in North Carolina; 14 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2018, 11:15 AM EDT for 17 counties in North Carolina; 14 counties in South Carolina. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 15, 2018, 11:15 AM EDT (15:15 UTC)
Expired: Apr 15, 2018, 1:15 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 31 counties

Alexander County, NC, Anson County, NC, Cabarrus County, NC, Catawba County, NC, Davidson County, NC, Davie County, NC, Forsyth County, NC, Gaston County, NC, Iredell County, NC, Lincoln County, NC, Mecklenburg County, NC, Montgomery County, NC, Richmond County, NC, Rowan County, NC, Stanly County, NC, Union County, NC, Yadkin County, NC, Barnwell County, SC, Calhoun County, SC, Chester County, SC, Chesterfield County, SC, Fairfield County, SC, Kershaw County, SC, Lancaster County, SC, Lee County, SC, Lexington County, SC, Newberry County, SC, Orangeburg County, SC, Richland County, SC, Sumter County, SC, York County, SC

The radar

The Columbia radar (KCAE), 112 km from the middle of the area, began a volume at 15:17 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 watches that followed

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

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 3.3 hours before the alert went out and 151 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: 28 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 638 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 98 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Apr 15, 12:13 PM EDT	Tornado Watch	SPC	Alexander, Alleghany, Ashe, Burke, Cabarrus, Caldwell and 16 more	9 hr
Apr 15, 2:29 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Caswell, Chatham, Cumberland, Davidson and 20 more	91 min
Apr 15, 3:02 PM EDT	Tornado Watch	SPC	Alamance, Anson, Bladen, Brunswick, Caswell, Chatham and 34 more	8 hr
Apr 15, 3:17 PM EDT	Mesoscale Discussion	SPC	Anson, Cabarrus, Davidson, Davie, Forsyth, Rowan and 3 more	88 min
Apr 15, 5:45 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Cabarrus, Caswell, Chatham, Cumberland and 24 more	90 min
Apr 15, 6:28 PM EDT	Mesoscale Discussion	SPC	Cumberland, Franklin, Granville, Halifax, Johnston, Nash and 4 more	62 min

Nearby

Mesoscale Discussions in North Carolina, 2018 Mesoscale Discussions in South Carolina, 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.