Alert archive / Pennsylvania / Mesoscale Discussions in 2013

Mesoscale Discussion 1337

July 7, 20136 states

The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2013, 6:09 PM EDT for 6 states. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Jul 7, 2013, 6:09 PM EDT (22:09 UTC)
Expired: Jul 7, 2013, 7:15 PM EDT
In force: 66 min
Issued by: the Storm Prediction Center

All 59 counties

New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Prince George's County, MD, Queen Anne's County, MD, Bergen County, NJ, Camden County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Westchester County, NY, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lackawanna County, PA, Lancaster County, PA, Lehigh County, PA, Luzerne County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Prince William County, VA

The radar

The Philadelphia radar (KDIX), 114 km from the middle of the area, began a volume at 22:12 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, 10.2 hours before the alert went out and 199 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: 285 J/kg
Mixed-layer CIN: -180 J/kg
Mixed-layer LCL: 1178 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 16 m²/s²
0-3 km storm-relative helicity: 55 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
Jul 7, 12:48 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett, Washington	117 min
Jul 7, 1:16 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Anne Arundel, Baltimore, Carroll, Frederick, Harford and 5 more	6 hr
Jul 7, 3:19 PM EDT	Mesoscale Discussion	SPC	Baltimore, Carroll, Frederick, Harford, Howard, Montgomery and 2 more	116 min
Jul 7, 4:45 PM EDT	Severe Thunderstorm Watch	SPC	Cecil	5 hr
Jul 7, 2:16 PM EDT	Mesoscale Discussion	SPC	Albany, Columbia, Dutchess, Greene, Putnam, Rensselaer and 6 more	119 min

Nearby

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