Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 172

February 28, 20117 counties in Maryland; 70 counties in Virginia; 13 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2011, 8:36 AM EST for 7 counties in Maryland; 70 counties in Virginia; 13 counties in West Virginia. It was in force for 24 min.

The area

The outline as issued.

The facts

Issued: Feb 28, 2011, 8:36 AM EST (13:36 UTC)
Expired: Feb 28, 2011, 9:00 AM EST
In force: 24 min
Issued by: the Storm Prediction Center

All 90 counties

Allegany County, MD, Carroll County, MD, Frederick County, MD, Garrett County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Albemarle County, VA, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, City of Bristol, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Galax, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Norton, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Giles County, VA, Grayson County, VA, Greene County, VA, Henry County, VA, Highland County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Montgomery County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Prince William County, VA, Pulaski County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Russell County, VA, Scott County, VA, Shenandoah County, VA, Smyth County, VA, Tazewell County, VA, Warren County, VA, Washington County, VA, Wythe County, VA, Berkeley County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, McDowell County, WV, Mercer County, WV, Mineral County, WV, Monroe County, WV, Morgan County, WV, Pendleton County, WV, Summers County, WV

The radar

The Roanoke radar (KFCX), 136 km from the middle of the area, began a volume at 13:37 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.

Tornado Watch 32Feb 28, 9:00 AM EST

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 1.6 hours before the alert went out and 102 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: 4 J/kg
Mixed-layer CIN: -263 J/kg
Mixed-layer LCL: 825 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 268 m²/s²
0-3 km storm-relative helicity: 373 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
Feb 28, 8:57 AM EST	Tornado Watch	SPC	Allegany, Calvert, Carroll, Charles, Frederick, Howard and 4 more	9 hr
Feb 28, 12:49 PM EST	Mesoscale Discussion	SPC	Calvert, Caroline, Charles, Dorchester, Saint Mary's, Somerset and 2 more	56 min
Feb 28, 5:47 AM EST	Tornado Watch	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Washington and 3 more	5 hr
Feb 28, 6:59 AM EST	Tornado Watch	SPC	Lee, Russell, Scott, Washington, Wise, City of Bristol and 1 more	7 hr
Feb 28, 12:25 PM EST	Mesoscale Discussion	SPC	Russell, Scott, Washington, City of Bristol	95 min
Feb 28, 4:36 PM EST	Mesoscale Discussion	SPC	City of Danville	84 min
Feb 28, 5:31 AM EST	Mesoscale Discussion	SPC	Boone, Braxton, Brooke, Cabell, Calhoun, Clay and 27 more	29 min

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in West Virginia, 2011 Mesoscale Discussions in Maryland, 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.