Alert archive / West Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1390

July 4, 20125 states

The Storm Prediction Center issued this mesoscale discussion at Jul 4, 2012, 4:04 PM EDT for 5 states. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued: Jul 4, 2012, 4:04 PM EDT (20:04 UTC)
Expired: Jul 4, 2012, 5:00 PM EDT
In force: 56 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 44 counties

Allegany County, MD, Garrett County, MD, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Guernsey County, OH, Harrison County, OH, Jefferson County, OH, Monroe County, OH, Noble County, OH, Allegheny County, PA, Beaver County, PA, Butler County, PA, Fayette County, PA, Greene County, PA, Lawrence County, PA, Somerset County, PA, Washington County, PA, Westmoreland County, PA, City of Winchester, VA, Frederick County, VA, Shenandoah County, VA, Barbour County, WV, Brooke County, WV, Doddridge County, WV, Grant County, WV, Hampshire County, WV, Hancock County, WV, Hardy County, WV, Harrison County, WV, Marion County, WV, Marshall County, WV, Mineral County, WV, Monongalia County, WV, Morgan County, WV, Ohio County, WV, Pendleton County, WV, Preston County, WV, Randolph County, WV, Taylor County, WV, Tucker County, WV, Tyler County, WV, Upshur County, WV, Wetzel County, WV

The radar

The Pittsburgh radar (KPBZ), 71 km from the middle of the area, began a volume at 20:05 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.

Severe Thunderstorm Watch 461Jul 4, 4:25 PM EDT

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 8.1 hours before the alert went out and 59 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: 1056 J/kg
Mixed-layer CIN: -119 J/kg
Mixed-layer LCL: 1050 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 197 m²/s²
0-3 km storm-relative helicity: 237 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.3

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
Jul 4, 4:26 PM EDT	Severe Thunderstorm Watch	SPC	Garrett	6 hr
Jul 4, 8:38 AM EDT	Mesoscale Discussion	SPC	Ashtabula, Columbiana, Cuyahoga, Geauga, Lake, Mahoning and 3 more	2 hr
Jul 4, 7:08 PM EDT	Mesoscale Discussion	SPC	Erie, Lucas, Ottawa, Sandusky, Seneca, Wood	2 hr
Jul 4, 6:46 PM EDT	Mesoscale Discussion	SPC	Bradford, Bucks, Carbon, Lackawanna, Lehigh, Luzerne and 6 more	59 min

Nearby

Mesoscale Discussions in West Virginia, 2012 Mesoscale Discussions in Pennsylvania, 2012 Mesoscale Discussions in Ohio, 2012 Every mesoscale discussion in 2012

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.