Alert archive / Virginia / Mesoscale Discussions in 2016

Mesoscale Discussion 1431

July 28, 201621 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2016, 9:22 PM EDT for 21 counties in Virginia. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Jul 28, 2016, 9:22 PM EDT (01:22 UTC)
Expired: Jul 28, 2016, 10:15 PM EDT
In force: 53 min
Issued by: the Storm Prediction Center

All 21 counties

Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Campbell County, VA, City of Buena Vista, VA, City of Covington, VA, City of Danville, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Roanoke County, VA

The radar

The Roanoke radar (KFCX), 51 km from the middle of the area, began a volume at 01:24 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 nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 1.4 hours before the alert went out and 21 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: 1057 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 1168 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 58 m²/s²
0-3 km storm-relative helicity: 133 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.9

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 28, 10:46 PM EDT	Mesoscale Discussion	SPC	Accomack, Amelia, Charles City, Chesterfield, Dinwiddie, Essex and 26 more	89 min

Nearby

Mesoscale Discussions in Virginia, 2016 Every mesoscale discussion in 2016

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.