Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 2141

September 6, 2011Rockingham County, Stokes County, North Carolina; 9 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Sep 6, 2011, 3:30 AM EDT for Rockingham County, Stokes County, North Carolina; 9 counties in Virginia. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Sep 6, 2011, 3:30 AM EDT (07:30 UTC)
Expired: Sep 6, 2011, 4:30 AM EDT
In force: 60 min
Issued by: the Storm Prediction Center

Counties Rockingham County, NC, Stokes County, NC, Campbell County, VA, Charlotte County, VA, City of Danville, VA, City of Martinsville, VA, Franklin County, VA, Halifax County, VA, Henry County, VA, Patrick County, VA, Pittsylvania County, VA

The radar

The Roanoke radar (KFCX), 79 km from the middle of the area, began a volume at 07:30 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.

Tornado Watch 845Sep 6, 5:20 AM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 7.5 hours before the alert went out and 43 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: -18 J/kg
Mixed-layer LCL: 634 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 108 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 5, 8:36 PM EDT	Mesoscale Discussion	SPC	Anson, Cumberland, Hoke, Montgomery, Moore, Richmond and 3 more	84 min
Sep 5, 11:47 PM EDT	Mesoscale Discussion	SPC	Stokes, Surry	88 min
Sep 6, 4:36 AM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Cabarrus, Caswell, Chatham, Davidson and 22 more	84 min
Sep 6, 5:17 AM EDT	Tornado Watch	SPC	Alamance, Alleghany, Anson, Bladen, Brunswick, Caswell and 43 more	9 hr
Sep 6, 8:35 AM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Bladen, Brunswick, Cabarrus, Catawba and 42 more	85 min
Sep 6, 9:51 AM EDT	Tornado Watch	SPC	Alexander, Avery, Burke, Cabarrus, Caldwell, Catawba and 13 more	6 hr
Sep 6, 12:41 PM EDT	Mesoscale Discussion	SPC	Alamance, Alleghany, Anson, Beaufort, Bertie, Bladen and 55 more	64 min
Sep 6, 1:32 PM EDT	Tornado Watch	SPC	Alamance, Anson, Beaufort, Bertie, Bladen, Brunswick and 48 more	7 hr
Sep 6, 4:41 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Beaufort, Bertie, Bladen, Brunswick and 46 more	64 min
Sep 6, 7:33 PM EDT	Mesoscale Discussion	SPC	Beaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 38 more	117 min

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in North Carolina, 2011 Every mesoscale discussion in 2011

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.