Alert archive / Pennsylvania / Mesoscale Discussions in 2018

Mesoscale Discussion 352

May 4, 20184 states

The Storm Prediction Center issued this mesoscale discussion at May 4, 2018, 4:20 PM EDT for 4 states. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued: May 4, 2018, 4:20 PM EDT (20:20 UTC)
Expired: May 4, 2018, 5:15 PM EDT
In force: 55 min
Issued by: the Storm Prediction Center

All 70 counties

Allegany County, NY, Broome County, NY, Cattaraugus County, NY, Cayuga County, NY, Chautauqua County, NY, Chemung County, NY, Chenango County, NY, Cortland County, NY, Erie County, NY, Genesee County, NY, Jefferson County, NY, Lewis County, NY, Livingston County, NY, Madison County, NY, Monroe County, NY, Oneida County, NY, Onondaga County, NY, Ontario County, NY, Oswego County, NY, Schuyler County, NY, Seneca County, NY, Steuben County, NY, Tioga County, NY, Tompkins County, NY, Wayne County, NY, Wyoming County, NY, Yates County, NY, Ashtabula County, OH, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Harrison County, OH, Jefferson County, OH, Mahoning County, OH, Monroe County, OH, Trumbull County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Bradford County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Crawford County, PA, Elk County, PA, Erie County, PA, Forest County, PA, Greene County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, Lycoming County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Tioga County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Marshall County, WV, Ohio County, WV, Tyler County, WV, Wetzel County, WV

The radar

The Buffalo radar (KBUF), 116 km from the middle of the area, began a volume at 20:20 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.

Severe Thunderstorm Watch 77May 4, 6:20 PM EDT

The nearest sounding before it

Buffalo Intl Airport, NY (KBUF), launched 12:00Z, 8.3 hours before the alert went out and 114 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 4 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 682 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 271 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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.

Issued	Product	Office	Counties	Lasted
May 4, 1:04 PM EDT	Mesoscale Discussion	SPC	Cattaraugus, Chautauqua, Erie, Genesee, Livingston, Monroe and 1 more	86 min
May 4, 2:18 PM EDT	Mesoscale Discussion	SPC	Clinton, Essex, Franklin, Fulton, Hamilton, Herkimer and 5 more	87 min
May 4, 2:23 PM EDT	Mesoscale Discussion	SPC	Allegany, Cattaraugus, Cayuga, Chemung, Cortland, Erie and 17 more	97 min
May 4, 2:44 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Broome, Cattaraugus, Cayuga, Chautauqua, Chemung and 23 more	6 hr
May 4, 3:16 PM EDT	Tornado Watch	SPC	Clinton, Essex, Franklin, Fulton, Hamilton, Herkimer and 5 more	6 hr
May 4, 5:52 PM EDT	Mesoscale Discussion	SPC	Albany, Columbia, Delaware, Dutchess, Greene, Montgomery and 11 more	83 min
May 4, 6:20 PM EDT	Severe Thunderstorm Watch	SPC	Albany, Columbia, Delaware, Dutchess, Greene, Montgomery and 6 more	4 hr
May 4, 6:48 PM EDT	Mesoscale Discussion	SPC	Clinton, Essex, Franklin, Fulton, Hamilton, Herkimer and 5 more	117 min
May 4, 1:22 PM EDT	Severe Thunderstorm Watch	SPC	Ashland, Ashtabula, Crawford, Cuyahoga, Erie, Geauga and 22 more	5 hr
May 4, 4:30 PM EDT	Mesoscale Discussion	SPC	Adams, Athens, Brown, Butler, Clark, Clermont and 21 more	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2018 Mesoscale Discussions in New York, 2018 Mesoscale Discussions in Ohio, 2018 Every mesoscale discussion in 2018

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.