Alert archive / Pennsylvania / Mesoscale Discussions in 2017

Mesoscale Discussion 1211

July 1, 20176 states

The Storm Prediction Center issued this mesoscale discussion at Jul 1, 2017, 12:54 PM EDT for 6 states. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: Jul 1, 2017, 12:54 PM EDT (16:54 UTC)
Expired: Jul 1, 2017, 2:00 PM EDT
In force: 66 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 73 counties

Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Washington County, MD, Warren County, NJ, Broome County, NY, Chemung County, NY, Cortland County, NY, Schuyler County, NY, Tioga County, NY, Tompkins County, NY, Adams County, PA, Berks County, PA, Bradford County, PA, Bucks County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York 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, City of Winchester, VA, Clarke County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Prince William County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The State College radar (KCCX), 102 km from the middle of the area, began a volume at 16:53 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, 4.9 hours before the alert went out and 227 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: 160 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 564 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 95 m²/s²
0-3 km storm-relative helicity: 105 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 1, 1:34 PM EDT	Severe Thunderstorm Watch	SPC	Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 11 more	7 hr
Jul 1, 4:10 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Calvert, Carroll, Cecil, Frederick and 8 more	2 hr
Jul 1, 1:19 PM EDT	Severe Thunderstorm Watch	SPC	Bergen, Essex, Hudson, Passaic, Union	8 hr
Jul 1, 12:32 PM EDT	Mesoscale Discussion	SPC	Albany, Columbia, Fulton, Greene, Montgomery, Rensselaer and 5 more	118 min
Jul 1, 1:18 PM EDT	Mesoscale Discussion	SPC	Lee, Scott, City of Bristol	117 min

Nearby

Mesoscale Discussions in Pennsylvania, 2017 Mesoscale Discussions in Virginia, 2017 Mesoscale Discussions in Maryland, 2017 Every mesoscale discussion in 2017

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.