Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 1602

July 13, 201130 counties in North Carolina; 74 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 13, 2011, 1:43 PM EDT for 30 counties in North Carolina; 74 counties in Virginia. It was in force for 92 min.

The area

The outline as issued.

The facts

Issued: Jul 13, 2011, 1:43 PM EDT (17:43 UTC)
Expired: Jul 13, 2011, 3:15 PM EDT
In force: 92 min
Issued by: the Storm Prediction Center

All 104 counties

Alamance County, NC, Alexander County, NC, Alleghany County, NC, Caldwell County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Forsyth County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Iredell County, NC, Johnston County, NC, Lee County, NC, Nash County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wilkes County, NC, Yadkin County, NC, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Carroll County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Roanoke, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Sussex County, VA, Warren County, VA

The radar

The Roanoke radar (KFCX), 67 km from the middle of the area, began a volume at 17:44 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 638Jul 13, 2:20 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 5.7 hours before the alert went out and 22 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: 989 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 863 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: -46 m²/s²
0-3 km storm-relative helicity: -13 m²/s²
Significant tornado parameter: -0.1
Supercell composite: -1.5

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
Jul 13, 2:21 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Alexander, Anson, Caswell, Catawba, Chatham and 32 more	8 hr
Jul 13, 4:30 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Cabarrus, Caswell, Catawba, Chatham and 36 more	90 min
Jul 13, 7:36 PM EDT	Mesoscale Discussion	SPC	Alamance, Bertie, Bladen, Caswell, Chatham, Columbus and 33 more	54 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.