Alert archive / Virginia / Mesoscale Discussions in 2016

Mesoscale Discussion 1418

July 28, 201618 counties in Virginia; 10 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2016, 1:28 PM EDT for 18 counties in Virginia; 10 counties in West Virginia. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Jul 28, 2016, 1:28 PM EDT (17:28 UTC)
Expired: Jul 28, 2016, 4:00 PM EDT
In force: 3 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 28 counties

Alleghany County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, City of Covington, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Montgomery County, VA, Pulaski County, VA, Roanoke County, VA, Smyth County, VA, Tazewell County, VA, Wythe County, VA, Fayette County, WV, Greenbrier County, WV, McDowell County, WV, Mercer County, WV, Monroe County, WV, Nicholas County, WV, Raleigh County, WV, Summers County, WV, Webster County, WV, Wyoming County, WV

The radar

The Roanoke radar (KFCX), 55 km from the middle of the area, began a volume at 17:28 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.

Severe Thunderstorm Watch 419Jul 28, 2:05 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 5.5 hours before the alert went out and 89 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: 32 J/kg
Mixed-layer CIN: -194 J/kg
Mixed-layer LCL: 1180 m above ground
0-6 km bulk shear: 33 kt
0-1 km storm-relative helicity: 30 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.1

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
Jul 28, 12:58 PM EDT	Mesoscale Discussion	SPC	Albemarle, Arlington, Caroline, Clarke, Culpeper, Essex and 35 more	2 hr
Jul 28, 1:27 PM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 28 more	11 hr
Jul 28, 2:08 PM EDT	Severe Thunderstorm Watch	SPC	Alleghany, Amherst, Appomattox, Bath, Bedford, Bland and 29 more	10 hr
Jul 28, 2:57 PM EDT	Mesoscale Discussion	SPC	Accomack, Amelia, Brunswick, Charles City, Chesterfield, Dinwiddie and 36 more	3 hr
Jul 28, 4:10 PM EDT	Mesoscale Discussion	SPC	Albemarle, Alleghany, Amherst, Arlington, Augusta, Bath and 50 more	95 min
Jul 28, 6:52 PM EDT	Mesoscale Discussion	SPC	Albemarle, Alleghany, Amherst, Appomattox, Arlington, Augusta and 63 more	83 min

Nearby

Mesoscale Discussions in Virginia, 2016 Mesoscale Discussions in West Virginia, 2016 Every mesoscale discussion in 2016

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.