Alert archive / Pennsylvania / Mesoscale Discussions in 2017

Mesoscale Discussion 1557

August 22, 201712 counties in New Jersey; 14 counties in New York; 30 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Aug 22, 2017, 7:07 PM EDT for 12 counties in New Jersey; 14 counties in New York; 30 counties in Pennsylvania. It was in force for 113 min.

The area

The outline as issued.

The facts

Issued
Aug 22, 2017, 7:07 PM EDT (23:07 UTC)
Expired
Aug 22, 2017, 9:00 PM EDT
In force
113 min
Issued by
the Storm Prediction Center
All 56 counties

Bergen County, NJ, Essex County, NJ, Hudson County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Union County, NJ, Warren County, NJ, Bronx County, NY, Columbia County, NY, Delaware County, NY, Dutchess County, NY, Greene County, NY, Kings County, NY, New York County, NY, Orange County, NY, Putnam County, NY, Richmond County, NY, Rockland County, NY, Sullivan County, NY, Ulster County, NY, Westchester County, NY, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Franklin County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne 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, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Wayne County, PA, Wyoming County, PA, York County, PA

The radar

The Binghamton radar (KBGM), 135 km from the middle of the area, began a volume at 23:07 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 nearest sounding before it

Brookhaven, NY (KOKX), launched 12:00Z, 11.1 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, Brookhaven, NY at 12:00Z on 2017-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 630 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 2017-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 78 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
630 J/kg
Mixed-layer CIN
-50 J/kg
Mixed-layer LCL
827 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
78 m²/s²
0-3 km storm-relative helicity
125 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.9

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 22, 3:55 PM EDTSevere Thunderstorm WatchSPCCapitol Planning Region, Northwest Hills Planning Region8 hr
Aug 22, 4:19 PM EDTSevere Thunderstorm WatchSPCGreater Bridgeport Planning Region8 hr
Aug 22, 3:08 PM EDTMesoscale DiscussionSPCBergen, Essex, Hunterdon, Morris, Passaic, Somerset and 2 more67 min
Aug 22, 11:55 AM EDTMesoscale DiscussionSPCAllegany, Broome, Cattaraugus, Cayuga, Chemung, Chenango and 23 more3 hr
Aug 22, 12:23 PM EDTTornado WatchSPCAllegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 36 more9 hr
Aug 22, 2:44 PM EDTMesoscale DiscussionSPCAllegany, Broome, Cayuga, Chemung, Chenango, Clinton and 22 more2 hr
Aug 22, 4:48 PM EDTMesoscale DiscussionSPCBroome, Cayuga, Chemung, Chenango, Clinton, Cortland and 21 more87 min
Aug 22, 5:49 PM EDTMesoscale DiscussionSPCAlbany, Columbia, Greene, Rensselaer, Washington116 min
Aug 22, 11:54 AM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Butler, Clarion, Greene and 5 more66 min
Aug 22, 12:39 PM EDTSevere Thunderstorm WatchSPCAllegheny, Armstrong, Beaver, Bedford, Blair, Butler and 16 more8 hr
Aug 22, 2:44 PM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Blair, Butler, Cambria and 13 more91 min
Aug 22, 4:39 PM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Blair, Butler, Cambria and 13 more66 min

Nearby

Mesoscale Discussions in Pennsylvania, 2017Mesoscale Discussions in New York, 2017Mesoscale Discussions in New Jersey, 2017Every mesoscale discussion in 2017

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.