Alert archive / Pennsylvania / Severe Thunderstorm Watches in 2004

Severe Thunderstorm Watch 235

May 21, 20044 states

The Storm Prediction Center issued this severe thunderstorm watch at May 21, 2004, 3:15 PM EDT for 4 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: May 21, 2004, 3:15 PM EDT (19:15 UTC)
Expired: May 21, 2004, 9:00 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 44 counties

Allegany County, NY, Cattaraugus County, NY, Ashtabula County, OH, Belmont County, OH, Carroll County, OH, Columbiana County, OH, Cuyahoga County, OH, Geauga County, OH, Guernsey County, OH, Harrison County, OH, Jefferson County, OH, Lake County, OH, Mahoning County, OH, Portage County, OH, Stark County, OH, Summit County, OH, Trumbull County, OH, Tuscarawas County, OH, Allegheny County, PA, Armstrong County, PA, Beaver County, PA, Blair County, PA, Butler County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Crawford County, PA, Elk County, PA, Forest County, PA, Indiana County, PA, Jefferson County, PA, Lawrence County, PA, McKean County, PA, Mercer County, PA, Potter County, PA, Venango County, PA, Warren County, PA, Washington County, PA, Westmoreland County, PA, Brooke County, WV, Hancock County, WV, Ohio County, WV

The radar

The Pittsburgh radar (KPBZ), 83 km from the middle of the area, began a volume at 19:19 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.

Warnings issued inside it

23 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
May 21, 3:43 PM EDT	Severe Thunderstorm Warning	CLE	Cuyahoga, Medina	62 min
May 21, 4:05 PM EDT	Flash Flood Warning	CLE	Cuyahoga, Lorain, Medina	4 hr
May 21, 4:06 PM EDT	Severe Thunderstorm Warning	CLE	Summit, Wayne	54 min
May 21, 4:11 PM EDT	Severe Thunderstorm Warning	CLE	Geauga, Lake	64 min
May 21, 4:18 PM EDT	Severe Thunderstorm Warning	CLE	Portage	57 min
May 21, 4:23 PM EDT	Severe Thunderstorm Warning	CLE	Holmes, Stark	67 min
May 21, 4:40 PM EDT	Severe Thunderstorm Warning	CLE	Ashtabula, Mahoning, Trumbull	65 min
May 21, 4:54 PM EDT	Severe Thunderstorm Warning	PBZ	Carroll, Columbiana, Tuscarawas	66 min
May 21, 5:04 PM EDT	Tornado Warning	CLE	Trumbull	26 min
May 21, 5:09 PM EDT	Severe Thunderstorm Warning	PBZ	Lawrence, Mercer	66 min
May 21, 5:12 PM EDT	Tornado Warning	CLE	Ashtabula	33 min
May 21, 5:15 PM EDT	Severe Thunderstorm Warning	CLE	Crawford	75 min
May 21, 5:23 PM EDT	Severe Thunderstorm Warning	PBZ	Guernsey, Harrison, Jefferson	67 min
May 21, 5:25 PM EDT	Flash Flood Warning	CLE	Ashtabula	4 hr
May 21, 5:26 PM EDT	Flash Flood Warning	PBZ	Carroll	3 hr
May 21, 5:41 PM EDT	Severe Thunderstorm Warning	PBZ	Butler, Venango	64 min
May 21, 5:50 PM EDT	Severe Thunderstorm Warning	PBZ	Belmont, Noble	55 min
May 21, 5:55 PM EDT	Flash Flood Warning	PBZ	Guernsey	3 hr
May 21, 6:16 PM EDT	Severe Thunderstorm Warning	PBZ	Armstrong, Clarion	59 min
May 21, 6:29 PM EDT	Severe Thunderstorm Warning	PBZ	Westmoreland	61 min
May 21, 6:44 PM EDT	Severe Thunderstorm Warning	PBZ	Indiana, Jefferson	61 min
May 21, 6:55 PM EDT	Severe Thunderstorm Warning	CTP	Cambria, Clearfield, Somerset	80 min
May 21, 7:30 PM EDT	Severe Thunderstorm Warning	CTP	Bedford, Blair	60 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Pittsburgh, PA (KPIT), launched 12:00Z, 7.3 hours before the alert went out and 97 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 873 m above ground
0-6 km bulk shear: 49 kt
0-1 km storm-relative helicity: -197 m²/s²
0-3 km storm-relative helicity: -213 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.

Issued	Product	Office	Counties	Lasted
May 21, 2:19 PM EDT	Mesoscale Discussion	SPC	Chautauqua	116 min
May 20, 10:05 PM EDT	Severe Thunderstorm Watch	SPC	Defiance, Fulton, Lucas, Williams	5 hr
May 21, 2:40 AM EDT	Mesoscale Discussion	SPC	Ashland, Carroll, Columbiana, Coshocton, Crawford, Cuyahoga and 20 more	65 min
May 21, 4:45 AM EDT	Mesoscale Discussion	SPC	Belmont, Carroll, Columbiana, Coshocton, Fairfield, Franklin and 12 more	60 min
May 21, 10:40 AM EDT	Mesoscale Discussion	SPC	Allen, Crawford, Cuyahoga, Defiance, Erie, Fulton and 14 more	2 hr
May 21, 1:05 PM EDT	Severe Thunderstorm Watch	SPC	Allen, Ashland, Auglaize, Champaign, Coshocton, Crawford and 32 more	4 hr
May 21, 4:25 PM EDT	Severe Thunderstorm Watch	SPC	Athens, Auglaize, Champaign, Clark, Clinton, Darke and 21 more	6 hr
May 21, 6:35 PM EDT	Severe Thunderstorm Watch	SPC	Gallia, Meigs	4 hr
May 21, 6:53 PM EDT	Mesoscale Discussion	SPC	Adams, Allegheny, Armstrong, Bedford, Berks, Blair and 47 more	97 min
May 21, 8:34 AM EDT	Mesoscale Discussion	SPC	Jefferson	86 min
May 21, 5:31 PM EDT	Mesoscale Discussion	SPC	Barbour, Berkeley, Boone, Braxton, Calhoun, Clay and 30 more	89 min

Nearby

Severe Thunderstorm Watches in Pennsylvania, 2004 Severe Thunderstorm Watches in Ohio, 2004 Severe Thunderstorm Watches in West Virginia, 2004 Every severe thunderstorm watch in 2004

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.