Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 2056

August 25, 201156 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 25, 2011, 2:47 PM EDT for 56 counties in Virginia. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Aug 25, 2011, 2:47 PM EDT (18:47 UTC)
Expired: Aug 25, 2011, 3:45 PM EDT
In force: 58 min
Issued by: the Storm Prediction Center

All 56 counties

Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline 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 Fredericksburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Roanoke, VA, City of Salem, VA, City of Waynesboro, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greene County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, King George County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Montgomery County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Roanoke County, VA, Rockbridge County, VA, Spotsylvania County, VA, Stafford County, VA

The radar

The Norfolk radar (KAKQ), 148 km from the middle of the area, began a volume at 18:49 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 807Aug 25, 3:25 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 6.8 hours before the alert went out and 109 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: 459 J/kg
Mixed-layer CIN: -147 J/kg
Mixed-layer LCL: 1055 m above ground
0-6 km bulk shear: 22 kt
0-1 km storm-relative helicity: 124 m²/s²
0-3 km storm-relative helicity: 77 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 25, 3:23 PM EDT	Severe Thunderstorm Watch	SPC	Accomack, Albemarle, Amelia, Amherst, Appomattox, Arlington and 61 more	5 hr
Aug 25, 6:24 PM EDT	Mesoscale Discussion	SPC	Accomack, Amelia, Brunswick, Caroline, Charles City, Chesterfield and 45 more	96 min

Nearby

Mesoscale Discussions in Virginia, 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.