Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 1426

July 7, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2012, 1:48 PM EDT for 4 states. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued
Jul 7, 2012, 1:48 PM EDT (17:48 UTC)
Expired
Jul 7, 2012, 2:45 PM EDT
In force
57 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 31 counties

Cattaraugus County, NY, Carroll County, OH, Columbiana County, OH, Holmes County, OH, Mahoning County, OH, Medina County, OH, Portage County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Wayne County, OH, Armstrong County, PA, Beaver County, PA, Butler County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Crawford County, PA, Elk County, PA, Forest County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Venango County, PA, Warren County, PA, Hancock County, WV

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 5.8 hours before the alert went out and 112 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 12:00Z on 2012-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 326 joules per kilogram.LCLLFCEL10008507005003002001001 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 12:00Z on 2012-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 82 square meters per square second.1939Sfc1 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
326 J/kg
Mixed-layer CIN
-226 J/kg
Mixed-layer LCL
1593 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
82 m²/s²
0-3 km storm-relative helicity
66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.9

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.

IssuedProductOfficeCountiesLasted
Jul 7, 11:19 AM EDTMesoscale DiscussionSPCBronx, Broome, Delaware, Dutchess, Greene, Kings and 10 more86 min
Jul 7, 11:41 AM EDTSevere Thunderstorm WatchSPCBronx, Dutchess, Kings, Nassau, New York, Orange and 8 more7 hr
Jul 7, 1:36 PM EDTMesoscale DiscussionSPCBronx, Dutchess, Kings, Nassau, New York, Orange and 8 more84 min
Jul 7, 3:57 PM EDTMesoscale DiscussionSPCBronx, Kings, Nassau, New York, Orange, Putnam and 6 more2 hr
Jul 7, 5:43 PM EDTMesoscale DiscussionSPCBronx, Kings, Nassau, New York, Queens, Richmond62 min
Jul 7, 2:16 PM EDTSevere Thunderstorm WatchSPCAshland, Belmont, Carroll, Columbiana, Coshocton, Guernsey and 13 more5 hr
Jul 7, 6:59 PM EDTSevere Thunderstorm WatchSPCBelmont, Carroll, Columbiana, Harrison, Jefferson, Tuscarawas3 hr
Jul 7, 6:14 PM EDTSevere Thunderstorm WatchSPCAdams, Bedford, Berks, Blair, Bucks, Cambria and 29 more3 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in Ohio, 2012Mesoscale Discussions in New York, 2012Every 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.