Alert archive / Virginia / Mesoscale Discussions in 2013

Mesoscale Discussion 1549

July 28, 20135 states

The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2013, 1:34 PM EDT for 5 states. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Jul 28, 2013, 1:34 PM EDT (17:34 UTC)
Expired: Jul 28, 2013, 2:30 PM EDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 58 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Calvert County, MD, Caroline County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Harford County, MD, Kent County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Mercer County, NJ, Salem County, NJ, Bucks County, PA, Delaware County, PA, Philadelphia County, PA, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Richmond, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Goochland County, VA, Hanover County, VA, Henrico County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Middlesex County, VA, New Kent County, VA, Northumberland County, VA, Orange County, VA, Prince William County, VA, Richmond County, VA, Spotsylvania County, VA, Stafford County, VA, Westmoreland County, VA

The radar

The Dover AFB radar (KDOX), 82 km from the middle of the area, began a volume at 17:36 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.6 hours before the alert went out and 99 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: 325 J/kg
Mixed-layer CIN: -85 J/kg
Mixed-layer LCL: 818 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 156 m²/s²
0-3 km storm-relative helicity: 152 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.5

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
Jul 28, 6:33 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	117 min
Jul 28, 11:31 AM EDT	Mesoscale Discussion	SPC	Berks, Carbon, Columbia, Dauphin, Lackawanna, Lancaster and 10 more	59 min

Nearby

Mesoscale Discussions in Virginia, 2013 Mesoscale Discussions in Maryland, 2013 Mesoscale Discussions in New Jersey, 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.