Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 116

February 20, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Feb 20, 2011, 11:50 PM EST for 4 states. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Feb 20, 2011, 11:50 PM EST (04:50 UTC)
Expired
Feb 21, 2011, 4:45 AM EST
In force
5 hr
Issued by
the Storm Prediction Center
All 63 counties

Sussex County, NJ, Allegany County, NY, Broome County, NY, Cattaraugus County, NY, Chautauqua County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Delaware County, NY, Erie County, NY, Genesee County, NY, Livingston County, NY, Ontario County, NY, Orange County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Sullivan County, NY, Tioga County, NY, Tompkins County, NY, Ulster County, NY, Wyoming County, NY, Yates County, NY, Ashtabula County, OH, Geauga County, OH, Mahoning County, OH, Portage County, OH, Trumbull County, OH, Bradford County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Carbon County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Crawford County, PA, Elk County, PA, Erie County, PA, Forest County, PA, Indiana County, PA, Jefferson County, PA, Lackawanna County, PA, Lawrence County, PA, Luzerne County, PA, Lycoming County, PA, McKean County, PA, Mercer County, PA, Monroe County, PA, Montour County, PA, Northumberland County, PA, Pike County, PA, Potter County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Venango County, PA, Warren County, PA, Wayne County, PA, Wyoming County, PA

The radar

The Buffalo radar (KBUF), 114 km from the middle of the area, began a volume at 04:52 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 00:00Z, 4.8 hours before the alert went out and 242 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-pSkew-T log-p diagram, Pittsburgh, PA at 00:00Z on 2011-02-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Pittsburgh, PA at 00:00Z on 2011-02-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 615 square meters per square second.1939587897117136Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
455 m above ground
0-6 km bulk shear
73 kt
0-1 km storm-relative helicity
615 m²/s²
0-3 km storm-relative helicity
1010 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.

IssuedProductOfficeCountiesLasted
Feb 20, 7:46 PM ESTMesoscale DiscussionSPCAllegany, Cattaraugus, Chautauqua, Chemung, Erie, Livingston and 4 more4 hr
Feb 21, 10:20 AM ESTMesoscale DiscussionSPCAllen, Ashland, Auglaize, Champaign, Crawford, Darke and 30 more5 hr
Feb 21, 6:33 PM ESTMesoscale DiscussionSPCBelmont, Fairfield, Franklin, Guernsey, Hocking, Licking and 8 more5 hr
Feb 21, 5:58 PM ESTMesoscale DiscussionSPCAdams, Allegheny, Armstrong, Bedford, Blair, Cambria and 12 more4 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2011Mesoscale Discussions in New York, 2011Mesoscale Discussions in Ohio, 2011Every 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.