Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 576

April 25, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2011, 6:00 PM EDT for 4 states. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued: Apr 25, 2011, 6:00 PM EDT (22:00 UTC)
Expired: Apr 25, 2011, 7:00 PM EDT
In force: 60 min
Issued by: the Storm Prediction Center

All 52 counties

Chemung County, NY, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Coshocton County, OH, Guernsey County, OH, Harrison County, OH, Holmes County, OH, Jefferson County, OH, Mahoning County, OH, Monroe County, OH, Morgan County, OH, Muskingum County, OH, Noble County, OH, Portage County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Tuscarawas County, OH, Wayne County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Elk County, PA, Forest County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lawrence County, PA, Lycoming County, PA, Mercer County, PA, Mifflin County, PA, Potter County, PA, Snyder County, PA, Tioga County, PA, Union County, PA, Venango County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marshall County, WV, Ohio County, WV

The radar

The Pittsburgh radar (KPBZ), 25 km from the middle of the area, began a volume at 22:00 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

Pittsburgh, PA (KPIT), launched 12:00Z, 10.0 hours before the alert went out and 22 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: 4 J/kg
Mixed-layer CIN: -53 J/kg
Mixed-layer LCL: 698 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 66 m²/s²
0-3 km storm-relative helicity: 87 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 25, 1:52 PM EDT	Mesoscale Discussion	SPC	Ashland, Belmont, Carroll, Columbiana, Coshocton, Cuyahoga and 21 more	83 min
Apr 25, 2:47 PM EDT	Severe Thunderstorm Watch	SPC	Belmont, Carroll, Columbiana, Coshocton, Guernsey, Harrison and 12 more	7 hr
Apr 24, 9:02 PM EDT	Mesoscale Discussion	SPC	Barbour, Braxton, Grant, Hampshire, Hardy, Jefferson and 7 more	58 min

Nearby

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