Alert archive / Virginia / Mesoscale Discussions in 2007

Mesoscale Discussion 1771

August 16, 200776 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 16, 2007, 2:55 PM EDT for 76 counties in Virginia. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Aug 16, 2007, 2:55 PM EDT (18:55 UTC)
Expired: Aug 16, 2007, 5:30 PM EDT
In force: 3 hr
Issued by: the Storm Prediction Center

All 76 counties

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, 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 Emporia, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, 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 Staunton, VA, City of Suffolk, VA, City of Waynesboro, VA, City of Williamsburg, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mathews County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 89 km from the middle of the area, began a volume at 18:57 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 606Aug 16, 4:45 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 6.9 hours before the alert went out and 177 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: 182 J/kg
Mixed-layer CIN: -257 J/kg
Mixed-layer LCL: 1638 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 92 m²/s²
0-3 km storm-relative helicity: 86 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.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 16, 4:44 PM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Amelia, Amherst, Appomattox, Augusta, Bedford and 74 more	6 hr
Aug 16, 7:39 PM EDT	Severe Thunderstorm Watch	SPC	Alleghany, Bath, Craig, Giles, Highland, City of Covington	3 hr
Aug 16, 7:48 PM EDT	Mesoscale Discussion	SPC	Accomack, Albemarle, Amelia, Amherst, Appomattox, Arlington and 97 more	57 min

Nearby

Mesoscale Discussions in Virginia, 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.