Alert archive / Virginia / Mesoscale Discussions in 2018

Mesoscale Discussion 1277

August 12, 201812 counties in North Carolina; 44 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Aug 12, 2018, 2:18 PM EDT for 12 counties in North Carolina; 44 counties in Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Aug 12, 2018, 2:18 PM EDT (18:18 UTC)
Expired: Aug 12, 2018, 4:45 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 56 counties

Caswell County, NC, Davie County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Person County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wilkes County, NC, Yadkin County, NC, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Danville, VA, City of Fredericksburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Roanoke, VA, City of Salem, VA, City of Waynesboro, VA, Culpeper County, VA, Cumberland County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Goochland County, VA, Greene County, VA, Halifax County, VA, Hanover County, VA, Henry County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 6.3 hours before the alert went out and 68 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: 715 J/kg
Mixed-layer CIN: -36 J/kg
Mixed-layer LCL: 838 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 1 m²/s²
0-3 km storm-relative helicity: 27 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

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Nearby

Mesoscale Discussions in Virginia, 2018 Mesoscale Discussions in North Carolina, 2018 Every mesoscale discussion in 2018

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.