Alert archive / Virginia / Mesoscale Discussions in 2007

Mesoscale Discussion 2025

September 27, 20074 states

The Storm Prediction Center issued this mesoscale discussion at Sep 27, 2007, 1:00 PM EDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 27, 2007, 1:00 PM EDT (17:00 UTC)
Expired: Sep 27, 2007, 3:00 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 100 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Garrett County, MD, Montgomery County, MD, Washington County, MD, Adams County, PA, Bedford County, PA, Cumberland County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Perry County, PA, Albemarle County, VA, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Galax, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Giles County, VA, Grayson County, VA, Greene County, VA, Highland County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Montgomery County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Prince William County, VA, Pulaski County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Smyth County, VA, Spotsylvania County, VA, Tazewell County, VA, Warren County, VA, Wythe County, VA, Barbour County, WV, Berkeley County, WV, Fayette County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, McDowell County, WV, Mercer County, WV, Mineral County, WV, Monroe County, WV, Morgan County, WV, Nicholas County, WV, Pendleton County, WV, Pocahontas County, WV, Raleigh County, WV, Randolph County, WV, Summers County, WV, Tucker County, WV, Upshur County, WV, Webster County, WV, Wyoming County, WV

The radar

The Sterling radar (KLWX), 174 km from the middle of the area, began a volume at 17:02 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 691Sep 27, 2:15 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 5.0 hours before the alert went out and 143 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: 272 J/kg
Mixed-layer CIN: -94 J/kg
Mixed-layer LCL: 998 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -29 m²/s²
0-3 km storm-relative helicity: 41 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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 27, 2:11 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Garrett, Washington	8 hr
Sep 27, 12:43 PM EDT	Mesoscale Discussion	SPC	Bradford, Carbon, Columbia, Lackawanna, Luzerne, Lycoming and 11 more	2 hr
Sep 27, 7:01 PM EDT	Mesoscale Discussion	SPC	Adams, Bradford, Carbon, Columbia, Cumberland, Dauphin and 18 more	89 min

Nearby

Mesoscale Discussions in Virginia, 2007 Mesoscale Discussions in West Virginia, 2007 Mesoscale Discussions in Pennsylvania, 2007 Every mesoscale discussion in 2007

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.