Alert archive / Virginia / Mesoscale Discussions in 2018

Mesoscale Discussion 268

April 15, 201826 counties in North Carolina; Chesterfield County, Dillon County, Marlboro County, South Carolina; 27 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2018, 2:29 PM EDT for 26 counties in North Carolina; Chesterfield County, Dillon County, Marlboro County, South Carolina; 27 counties in Virginia. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Apr 15, 2018, 2:29 PM EDT (18:29 UTC)
Expired: Apr 15, 2018, 4:00 PM EDT
In force: 91 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 56 counties

Alamance County, NC, Anson County, NC, Caswell County, NC, Chatham County, NC, Cumberland County, NC, Davidson County, NC, Durham County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Harnett County, NC, Hoke County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Robeson County, NC, Rockingham County, NC, Scotland County, NC, Stanly County, NC, Stokes County, NC, Vance County, NC, Wake County, NC, Chesterfield County, SC, Dillon County, SC, Marlboro County, SC, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Danville, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Halifax County, VA, Henry County, VA, Mecklenburg County, VA, Montgomery County, VA, Nelson County, VA, Patrick County, VA, Pittsylvania County, VA, Prince Edward County, VA, Roanoke County, VA, Rockbridge County, VA

The radar

The Raleigh/Durham radar (KRAX), 108 km from the middle of the area, began a volume at 18:30 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, 6.5 hours before the alert went out and 37 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, 11:15 AM EDT	Mesoscale Discussion	SPC	Alexander, Anson, Cabarrus, Catawba, Davidson, Davie and 11 more	2 hr
Apr 15, 12:13 PM EDT	Tornado Watch	SPC	Alexander, Alleghany, Ashe, Burke, Cabarrus, Caldwell and 16 more	9 hr
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
Apr 15, 6:14 PM EDT	Tornado Watch	SPC	Amelia, Brunswick, Chesterfield, Cumberland, Dinwiddie, Fluvanna and 8 more	7 hr

Nearby

Mesoscale Discussions in Virginia, 2018 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.