Alert archive / Pennsylvania / Mesoscale Discussions in 2012

Mesoscale Discussion 1431

July 7, 20125 states

The Storm Prediction Center issued this mesoscale discussion at Jul 7, 2012, 5:43 PM EDT for 5 states. It was in force for 62 min.

The area

The outline as issued.

The facts

Issued
Jul 7, 2012, 5:43 PM EDT (21:43 UTC)
Expired
Jul 7, 2012, 6:45 PM EDT
In force
62 min
Issued by
the Storm Prediction Center
Chance of a watch
80%
All 60 counties

Kent County, DE, New Castle County, DE, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Kent County, MD, Washington County, MD, Atlantic County, NJ, Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Monmouth County, NJ, Morris County, NJ, Ocean County, NJ, Passaic County, NJ, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Queens County, NY, Richmond County, NY, Adams County, PA, Bedford County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Mifflin County, PA, Montgomery County, PA, Northampton County, PA, Perry County, PA, Philadelphia County, PA, Schuylkill County, PA, Snyder County, PA, York County, PA

The radar

The Philadelphia radar (KDIX), 117 km from the middle of the area, began a volume at 21:43 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.7 hours before the alert went out and 195 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, Washington/Dulle, VA at 12:00Z on 2012-07-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1804 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, Washington/Dulle, VA at 12:00Z on 2012-07-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 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
1804 J/kg
Mixed-layer CIN
-87 J/kg
Mixed-layer LCL
1395 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
90 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.1

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, 6:14 PM EDTSevere Thunderstorm WatchSPCNew Castle3 hr
Jul 7, 11:19 AM EDTMesoscale DiscussionSPCBergen, Essex, Hudson, Hunterdon, Mercer, Middlesex and 7 more86 min
Jul 7, 11:41 AM EDTSevere Thunderstorm WatchSPCBergen, Essex, Hudson, Hunterdon, Mercer, Middlesex and 6 more7 hr
Jul 7, 1:36 PM EDTMesoscale DiscussionSPCBergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more84 min
Jul 7, 3:57 PM EDTMesoscale DiscussionSPCBergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more2 hr
Jul 7, 1:48 PM EDTMesoscale DiscussionSPCCattaraugus57 min
Jul 7, 2:16 PM EDTSevere Thunderstorm WatchSPCAllegheny, Armstrong, Beaver, Blair, Butler, Cambria and 21 more5 hr
Jul 7, 6:59 PM EDTSevere Thunderstorm WatchSPCAllegheny, Beaver, Fayette, Greene, Washington, Westmoreland3 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in New Jersey, 2012Mesoscale Discussions in Maryland, 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; radar from the NEXRAD Level II archive.