Alert archive / Pennsylvania / Mesoscale Discussions in 2004

Mesoscale Discussion 806

May 21, 200453 counties in Pennsylvania

The Storm Prediction Center issued this mesoscale discussion at May 21, 2004, 6:53 PM EDT for 53 counties in Pennsylvania. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: May 21, 2004, 6:53 PM EDT (22:53 UTC)
Expired: May 21, 2004, 8:30 PM EDT
In force: 97 min
Issued by: the Storm Prediction Center

All 53 counties

Adams County, PA, Allegheny County, PA, Armstrong County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Bradford County, PA, Cambria County, PA, Cameron County, PA, Carbon County, PA, Centre County, PA, Chester County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Elk County, PA, Fayette County, PA, Forest County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lackawanna County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Luzerne County, PA, Lycoming County, PA, McKean County, PA, Mifflin County, PA, Monroe County, PA, Montgomery County, PA, Montour County, PA, Northampton County, PA, Northumberland County, PA, Perry County, PA, Potter County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Tioga County, PA, Union County, PA, Warren County, PA, Westmoreland County, PA, Wyoming County, PA, York County, PA

The radar

The State College radar (KCCX), 17 km from the middle of the area, began a volume at 22:56 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

Pittsburgh, PA (KPIT), launched 12:00Z, 10.9 hours before the alert went out and 182 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, 2:40 AM EDT	Mesoscale Discussion	SPC	Beaver, Butler, Lawrence, Mercer	65 min
May 21, 4:45 AM EDT	Mesoscale Discussion	SPC	Allegheny, Armstrong, Beaver, Butler, Fayette, Greene and 4 more	60 min
May 21, 2:19 PM EDT	Mesoscale Discussion	SPC	Beaver, Crawford, Erie, Lawrence, Mercer	116 min
May 21, 3:15 PM EDT	Severe Thunderstorm Watch	SPC	Allegheny, Armstrong, Beaver, Blair, Butler, Cambria and 17 more	6 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2004 Every mesoscale discussion 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.