Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 457

April 16, 201112 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Apr 16, 2011, 2:05 PM EDT for 12 counties in Pennsylvania. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: Apr 16, 2011, 2:05 PM EDT (18:05 UTC)
Expired: Apr 16, 2011, 3:00 PM EDT
In force: 55 min
Issued by: the Storm Prediction Center

Counties Adams County, PA, Bedford County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Perry County, PA, York County, PA

The radar

The State College radar (KCCX), 104 km from the middle of the area, began a volume at 18:05 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.

Tornado Watch 152Apr 16, 4:40 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.1 hours before the alert went out and 133 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 533 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 473 m²/s²
0-3 km storm-relative helicity: 699 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 16, 10:43 AM EDT	Mesoscale Discussion	SPC	Fayette, Greene, Washington	62 min
Apr 16, 1:34 PM EDT	Mesoscale Discussion	SPC	Beaver, Crawford, Lawrence, Mercer, Washington	116 min
Apr 16, 4:29 PM EDT	Mesoscale Discussion	SPC	Adams, Chester, Franklin, Fulton, Lancaster, York	31 min
Apr 16, 4:41 PM EDT	Tornado Watch	SPC	Adams, Bedford, Berks, Blair, Chester, Cumberland and 13 more	6 hr
Apr 16, 6:38 PM EDT	Mesoscale Discussion	SPC	Adams, Berks, Chester, Cumberland, Dauphin, Delaware and 13 more	97 min

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.