Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 559

April 24, 201111 counties in Maryland; 30 counties in Virginia; 13 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 24, 2011, 9:02 PM EDT for 11 counties in Maryland; 30 counties in Virginia; 13 counties in West Virginia. It was in force for 58 min.

The area

The outline as issued.

The facts

Issued: Apr 24, 2011, 9:02 PM EDT (01:02 UTC)
Expired: Apr 24, 2011, 10:00 PM EDT
In force: 58 min
Issued by: the Storm Prediction Center

All 54 counties

Anne Arundel County, MD, Calvert County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Arlington County, VA, Augusta County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Barbour County, WV, Braxton County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Lewis County, WV, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Tucker County, WV, Upshur County, WV, Webster County, WV

The radar

The Sterling radar (KLWX), 46 km from the middle of the area, began a volume at 01:05 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, 1.0 hours before the alert went out and 220 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: 3309 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 147 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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 25, 1:52 PM EDT	Mesoscale Discussion	SPC	Brooke, Hancock, Ohio	83 min
Apr 25, 2:47 PM EDT	Severe Thunderstorm Watch	SPC	Brooke, Hancock, Marshall, Ohio	7 hr
Apr 25, 6:00 PM EDT	Mesoscale Discussion	SPC	Brooke, Hancock, Marshall, Ohio	60 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.