Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 1786

July 29, 201116 counties in New Jersey; 22 counties in New York; 49 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Jul 29, 2011, 4:40 PM EDT for 16 counties in New Jersey; 22 counties in New York; 49 counties in Pennsylvania. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued
Jul 29, 2011, 4:40 PM EDT (20:40 UTC)
Expired
Jul 29, 2011, 6:15 PM EDT
In force
95 min
Issued by
the Storm Prediction Center
All 87 counties

Bergen County, NJ, Burlington County, NJ, Camden County, NJ, Essex 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, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Broome County, NY, Chemung County, NY, Chenango County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, Nassau County, NY, New York County, NY, Orange County, NY, Otsego County, NY, Putnam County, NY, Queens County, NY, Richmond County, NY, Rockland County, NY, Schoharie County, NY, Sullivan County, NY, Tioga County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bradford County, PA, Bucks County, PA, Cambria County, PA, Cameron County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Philadelphia County, PA, Pike County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Susquehanna County, PA, Tioga County, PA, Union County, PA, Wayne County, PA, Westmoreland County, PA, Wyoming County, PA, York County, PA

The radar

The Philadelphia radar (KDIX), 144 km from the middle of the area, began a volume at 20:40 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

Brookhaven, NY (KOKX), launched 12:00Z, 8.7 hours before the alert went out and 242 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, Brookhaven, NY at 12:00Z on 2011-07-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 81 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, Brookhaven, NY at 12:00Z on 2011-07-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 8 square meters per square second.193958Sfc1 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
81 J/kg
Mixed-layer CIN
-109 J/kg
Mixed-layer LCL
569 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
8 m²/s²
0-3 km storm-relative helicity
19 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.

IssuedProductOfficeCountiesLasted
Jul 29, 12:57 PM EDTMesoscale DiscussionSPCBergen, Essex, Hudson, Hunterdon, Morris, Passaic and 4 more2 hr
Jul 29, 2:40 PM EDTSevere Thunderstorm WatchSPCBergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more8 hr
Jul 29, 5:03 PM EDTTornado WatchSPCBergen, Passaic, Sussex3 hr
Jul 29, 6:17 PM EDTMesoscale DiscussionSPCSalem88 min
Jul 29, 3:31 AM EDTMesoscale DiscussionSPCAllegany, Cattaraugus, Chautauqua, Erie, Wyoming89 min
Jul 29, 3:56 AM EDTSevere Thunderstorm WatchSPCAllegany, Cattaraugus, Chautauqua, Erie, Genesee, Livingston and 1 more5 hr
Jul 29, 2:06 PM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Bedford, Blair, Butler and 9 more84 min

Nearby

Mesoscale Discussions in Pennsylvania, 2011Mesoscale Discussions in New York, 2011Mesoscale Discussions in New Jersey, 2011Every 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.