Alert archive / Virginia / Mesoscale Discussions in 2011

Mesoscale Discussion 1820

August 1, 20116 states

The Storm Prediction Center issued this mesoscale discussion at Aug 1, 2011, 3:22 PM EDT for 6 states. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued: Aug 1, 2011, 3:22 PM EDT (19:22 UTC)
Expired: Aug 1, 2011, 4:45 PM EDT
In force: 83 min
Issued by: the Storm Prediction Center

All 98 counties

Kent County, DE, New Castle County, DE, Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Garrett County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Washington County, MD, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Salem County, NJ, Somerset County, NJ, Warren County, NJ, Adams County, PA, Bedford County, PA, Berks County, PA, Bucks County, PA, Chester County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Mifflin County, PA, Montgomery County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, York County, PA, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Charlottesville, 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 Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, King George County, VA, Loudoun County, VA, Louisa 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, Westmoreland County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV

The radar

The Sterling radar (KLWX), 90 km from the middle of the area, began a volume at 19:23 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

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 7.4 hours before the alert went out and 84 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: 307 J/kg
Mixed-layer CIN: -150 J/kg
Mixed-layer LCL: 1512 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: -192 m²/s²
0-3 km storm-relative helicity: -166 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -1.5

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
Aug 1, 6:18 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	57 min
Aug 1, 2:15 PM EDT	Mesoscale Discussion	SPC	Bergen, Morris, Passaic, Sussex, Warren	90 min
Aug 1, 3:47 AM EDT	Mesoscale Discussion	SPC	Crawford, Erie, Warren	58 min
Aug 1, 8:01 AM EDT	Mesoscale Discussion	SPC	Bradford, Cameron, Clarion, Crawford, Elk, Erie and 7 more	89 min
Aug 1, 12:07 PM EDT	Mesoscale Discussion	SPC	Bradford, Cameron, Lackawanna, Lycoming, McKean, Potter and 5 more	53 min
Aug 1, 1:06 PM EDT	Mesoscale Discussion	SPC	Beaver, Lawrence	24 min
Aug 1, 1:19 PM EDT	Severe Thunderstorm Watch	SPC	Brooke, Hancock, Marshall, Ohio	6 hr
Aug 1, 3:39 PM EDT	Mesoscale Discussion	SPC	Brooke, Hancock, Ohio	66 min

Nearby

Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in Pennsylvania, 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.