Alert archive / Virginia / Mesoscale Discussions in 2013

Mesoscale Discussion 533

April 19, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2013, 1:27 PM EDT for 4 states. It was in force for 63 min.

The area

The outline as issued.

The facts

Issued: Apr 19, 2013, 1:27 PM EDT (17:27 UTC)
Expired: Apr 19, 2013, 2:30 PM EDT
In force: 63 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 109 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Frederick 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, Adams County, PA, Chester County, PA, Lancaster County, PA, York County, PA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, City of Williamsburg, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 78 km from the middle of the area, began a volume at 17:28 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.5 hours before the alert went out and 76 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: 16 J/kg
Mixed-layer CIN: -37 J/kg
Mixed-layer LCL: 705 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 215 m²/s²
0-3 km storm-relative helicity: 226 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 19, 2:31 PM EDT	Tornado Watch	SPC	Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more	7 hr
Apr 19, 4:36 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 9 more	114 min
Apr 19, 6:27 PM EDT	Severe Thunderstorm Watch	SPC	Somerset, Wicomico, Worcester	4 hr
Apr 19, 6:54 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Caroline, Charles, Dorchester, Howard and 7 more	66 min
Apr 19, 3:36 PM EDT	Mesoscale Discussion	SPC	Adams, Berks, Bradford, Carbon, Chester, Columbia and 25 more	54 min
Apr 19, 3:55 PM EDT	Tornado Watch	SPC	Adams, Berks, Bradford, Carbon, Centre, Chester and 30 more	6 hr
Apr 19, 6:02 PM EDT	Mesoscale Discussion	SPC	Adams, Berks, Bradford, Carbon, Chester, Columbia and 21 more	58 min
Apr 19, 7:12 PM EDT	Mesoscale Discussion	SPC	Bucks, Delaware, Montgomery, Philadelphia	93 min
Apr 19, 12:35 PM EDT	Mesoscale Discussion	SPC	Henry, City of Danville	115 min

Nearby

Mesoscale Discussions in Virginia, 2013 Mesoscale Discussions in Maryland, 2013 Mesoscale Discussions in Pennsylvania, 2013 Every mesoscale discussion in 2013

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.