Alert archive / Virginia / Mesoscale Discussions in 2013

Mesoscale Discussion 1685

August 10, 201320 counties in North Carolina; 72 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 10, 2013, 11:56 AM EDT for 20 counties in North Carolina; 72 counties in Virginia. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Aug 10, 2013, 11:56 AM EDT (15:56 UTC)
Expired: Aug 10, 2013, 1:30 PM EDT
In force: 94 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 92 counties

Bertie County, NC, Camden County, NC, Caswell County, NC, Chowan County, NC, Currituck County, NC, Durham County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Halifax County, NC, Hertford County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Rockingham County, NC, Vance County, NC, Warren County, NC, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Franklin County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Richmond County, VA, Rockbridge County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 26 km from the middle of the area, began a volume at 15:59 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 490Aug 10, 1:50 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 3.9 hours before the alert went out and 199 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: 536 J/kg
Mixed-layer CIN: -46 J/kg
Mixed-layer LCL: 640 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 3 m²/s²
0-3 km storm-relative helicity: 25 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.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 10, 1:22 PM EDT	Mesoscale Discussion	SPC	Caswell, Gates, Hertford, Northampton, Person, Vance and 1 more	53 min
Aug 10, 1:48 PM EDT	Severe Thunderstorm Watch	SPC	Amelia, Brunswick, Charles City, Chesterfield, Cumberland, Dinwiddie and 38 more	5 hr
Aug 10, 4:17 PM EDT	Mesoscale Discussion	SPC	Amelia, Brunswick, Charles City, Chesterfield, Cumberland, Dinwiddie and 36 more	58 min

Nearby

Mesoscale Discussions in Virginia, 2013 Mesoscale Discussions in North Carolina, 2013 Every mesoscale discussion in 2013

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.