Alert archive / North Carolina / Mesoscale Discussions in 2015

Mesoscale Discussion 239

April 8, 20157 counties in North Carolina; 5 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2015, 6:24 PM EDT for 7 counties in North Carolina; 5 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 8, 2015, 6:24 PM EDT (22:24 UTC)
Expired: Apr 8, 2015, 8:30 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Alamance County, NC, Caswell County, NC, Durham County, NC, Guilford County, NC, Orange County, NC, Person County, NC, Rockingham County, NC, City of Danville, VA, City of Martinsville, VA, Halifax County, VA, Henry County, VA, Pittsylvania County, VA

The radar

The Roanoke radar (KFCX), 101 km from the middle of the area, began a volume at 22:26 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

Roanoke, VA (KRNK), launched 12:00Z, 10.4 hours before the alert went out and 66 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: 57 J/kg
Mixed-layer CIN: -43 J/kg
Mixed-layer LCL: 645 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 156 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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 8, 12:33 PM EDT	Severe Thunderstorm Watch	SPC	Buchanan, Dickenson	5 hr
Apr 8, 1:51 PM EDT	Mesoscale Discussion	SPC	Alleghany, Bath, Bland, Buchanan, Craig, Dickenson and 14 more	84 min
Apr 8, 3:22 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson	83 min

Nearby

Mesoscale Discussions in North Carolina, 2015 Mesoscale Discussions in Virginia, 2015 Every mesoscale discussion in 2015

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.