Alert archive / Pennsylvania / Mesoscale Discussions in 2011

Mesoscale Discussion 647

April 27, 201121 counties in New York; 29 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 10:45 PM EDT for 21 counties in New York; 29 counties in Pennsylvania. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 10:45 PM EDT (02:45 UTC)
Expired
Apr 27, 2011, 11:45 PM EDT
In force
60 min
Issued by
the Storm Prediction Center
All 50 counties

Albany County, NY, Broome County, NY, Chenango County, NY, Delaware County, NY, Essex County, NY, Franklin County, NY, Fulton County, NY, Greene County, NY, Hamilton County, NY, Herkimer County, NY, Madison County, NY, Montgomery County, NY, Oneida County, NY, Otsego County, NY, Saratoga County, NY, Schenectady County, NY, Schoharie County, NY, Sullivan County, NY, Tioga County, NY, Ulster County, NY, Warren County, NY, Blair County, PA, Bradford County, PA, Cambria County, PA, Carbon County, PA, Centre County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Franklin County, PA, Huntingdon County, PA, Juniata County, PA, Lackawanna County, PA, Lebanon County, PA, Luzerne County, PA, Lycoming County, PA, Mifflin County, PA, Monroe County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Pike County, PA, Schuylkill County, PA, Snyder County, PA, Sullivan County, PA, Susquehanna County, PA, Union County, PA, Wayne County, PA, Wyoming County, PA

The radar

The Binghamton radar (KBGM), 5 km from the middle of the area, began a volume at 02:48 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

Albany, NY (KALY), launched 00:00Z, 2.8 hours before the alert went out and 189 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, Albany, NY at 00:00Z on 2011-04-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 108 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, Albany, NY at 00:00Z on 2011-04-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 307 square meters per square second.19395878Sfc1 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
108 J/kg
Mixed-layer CIN
-95 J/kg
Mixed-layer LCL
777 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
307 m²/s²
0-3 km storm-relative helicity
401 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.8

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
Apr 27, 8:15 PM EDTSevere Thunderstorm WatchSPCAlbany, Broome, Chenango, Clinton, Cortland, Delaware and 19 more8 hr
Apr 27, 9:03 PM EDTMesoscale DiscussionSPCCayuga, Chemung, Tioga, Tompkins57 min
Apr 28, 2:20 AM EDTMesoscale DiscussionSPCBroome, Chemung, Chenango, Cortland, Delaware, Fulton and 13 more55 min
Apr 28, 3:32 AM EDTMesoscale DiscussionSPCAlbany, Broome, Chenango, Delaware, Fulton, Greene and 15 more28 min
Apr 28, 4:05 AM EDTSevere Thunderstorm WatchSPCAlbany, Broome, Chenango, Cortland, Delaware, Fulton and 13 more6 hr
Apr 28, 6:21 AM EDTMesoscale DiscussionSPCAlbany, Chenango, Columbia, Delaware, Dutchess, Fulton and 15 more54 min
Apr 28, 9:45 AM EDTSevere Thunderstorm WatchSPCAlbany, Bronx, Columbia, Dutchess, Fulton, Greene and 19 more6 hr
Apr 28, 11:49 AM EDTMesoscale DiscussionSPCAlbany, Bronx, Columbia, Delaware, Dutchess, Fulton and 22 more56 min
Apr 27, 11:50 PM EDTSevere Thunderstorm WatchSPCAdams, Bedford, Blair, Cambria, Cameron, Centre and 26 more7 hr

Nearby

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