Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 991

May 26, 201127 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at May 26, 2011, 8:54 PM EDT for 27 counties in Pennsylvania. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued: May 26, 2011, 8:54 PM EDT (00:54 UTC)
Expired: May 26, 2011, 10:00 PM EDT
In force: 66 min
Issued by: the Storm Prediction Center

All 27 counties

Adams County, PA, Berks County, PA, Bradford County, PA, Carbon County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA, York County, PA

The radar

The Binghamton radar (KBGM), 125 km from the middle of the area, began a volume at 00:57 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 00:00Z, 0.9 hours before the alert went out and 259 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: 935 J/kg
Mixed-layer CIN: -39 J/kg
Mixed-layer LCL: 1937 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 185 m²/s²
0-3 km storm-relative helicity: 146 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 3.9

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
May 27, 12:24 PM EDT	Mesoscale Discussion	SPC	Adams, Berks, Bradford, Carbon, Columbia, Cumberland and 25 more	96 min
May 27, 12:57 PM EDT	Severe Thunderstorm Watch	SPC	Adams, Bedford, Berks, Blair, Bradford, Carbon and 31 more	9 hr
May 27, 6:14 PM EDT	Mesoscale Discussion	SPC	Adams, Bedford, Berks, Bradford, Carbon, Centre and 31 more	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 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.