Alert archive / Virginia / Mesoscale Discussions in 2005

Mesoscale Discussion 2239

September 20, 2005Charles County, Montgomery County, Prince George's County, Maryland; 5 counties in North Carolina; 41 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 20, 2005, 12:39 PM EDT for Charles County, Montgomery County, Prince George's County, Maryland; 5 counties in North Carolina; 41 counties in Virginia. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued: Sep 20, 2005, 12:39 PM EDT (16:39 UTC)
Expired: Sep 20, 2005, 2:15 PM EDT
In force: 96 min
Issued by: the Storm Prediction Center

All 49 counties

Charles County, MD, Montgomery County, MD, Prince George's County, MD, Caswell County, NC, Granville County, NC, Guilford County, NC, Person County, NC, Rockingham County, NC, Albemarle County, VA, Amelia County, VA, Appomattox County, VA, Arlington County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charlotte County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Danville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Goochland County, VA, Halifax County, VA, Hanover County, VA, Henry County, VA, King George County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Spotsylvania County, VA, Stafford County, VA

The radar

The Roanoke radar (KFCX), 154 km from the middle of the area, began a volume at 16:42 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 804Sep 20, 2:00 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 4.7 hours before the alert went out and 83 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: 14 J/kg
Mixed-layer CIN: -264 J/kg
Mixed-layer LCL: 1141 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 78 m²/s²
0-3 km storm-relative helicity: 83 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
Sep 20, 2:00 PM EDT	Severe Thunderstorm Watch	SPC	Saint Mary's, Somerset, Wicomico, Worcester	7 hr
Sep 20, 4:14 PM EDT	Mesoscale Discussion	SPC	Calvert, Caroline, Dorchester, Talbot, Wicomico	2 hr
Sep 20, 6:52 PM EDT	Mesoscale Discussion	SPC	Alamance, Caswell, Chatham, Durham, Edgecombe, Franklin and 17 more	83 min

Nearby

Mesoscale Discussions in Virginia, 2005 Mesoscale Discussions in North Carolina, 2005 Mesoscale Discussions in Maryland, 2005 Every mesoscale discussion in 2005

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.