Alert archive / Virginia / Mesoscale Discussions in 2008

Mesoscale Discussion 642

April 11, 200811 counties in Virginia; Pendleton County, Pocahontas County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2008, 6:56 PM EDT for 11 counties in Virginia; Pendleton County, Pocahontas County, West Virginia. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: Apr 11, 2008, 6:56 PM EDT (22:56 UTC)
Expired: Apr 11, 2008, 8:00 PM EDT
In force: 64 min
Issued by: the Storm Prediction Center

Counties Alleghany County, VA, Augusta County, VA, Bath County, VA, Botetourt County, VA, City of Buena Vista, VA, City of Covington, VA, City of Lexington, VA, City of Staunton, VA, City of Waynesboro, VA, Highland County, VA, Rockbridge County, VA, Pendleton County, WV, Pocahontas County, WV

The radar

The Roanoke radar (KFCX), 134 km from the middle of the area, began a volume at 22:57 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 nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 10.9 hours before the alert went out and 108 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1034 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 249 m²/s²
0-3 km storm-relative helicity: 249 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
Apr 11, 4:53 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Wise, City of Norton	67 min
Apr 11, 5:04 PM EDT	Severe Thunderstorm Watch	SPC	Alleghany, Bath, Buchanan, Dickenson, City of Covington	4 hr

Nearby

Mesoscale Discussions in Virginia, 2008 Mesoscale Discussions in West Virginia, 2008 Every mesoscale discussion in 2008

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.