Alert archive / Pennsylvania / Mesoscale Discussions in 2004

Mesoscale Discussion 1888

August 4, 20046 states

The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2004, 5:48 PM EDT for 6 states. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Aug 4, 2004, 5:48 PM EDT (21:48 UTC)
Expired: Aug 4, 2004, 7:45 PM EDT
In force: 117 min
Issued by: the Storm Prediction Center

All 48 counties

Kent County, DE, New Castle County, DE, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Queen Anne's County, MD, Washington County, MD, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Essex County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Salem County, NJ, Somerset County, NJ, Union County, NJ, Warren County, NJ, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Schuylkill County, PA, York County, PA, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Berkeley County, WV, Jefferson County, WV

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 710Aug 4, 7:10 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.8 hours before the alert went out and 143 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: 24 J/kg
Mixed-layer CIN: -92 J/kg
Mixed-layer LCL: 1125 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -2 m²/s²
0-3 km storm-relative helicity: -4 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
Aug 4, 7:10 PM EDT	Severe Thunderstorm Watch	SPC	Kent, New Castle	4 hr
Aug 4, 2:31 PM EDT	Mesoscale Discussion	SPC	Allegany, Garrett, Washington	119 min
Aug 4, 2:55 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Carroll, Frederick, Garrett, Washington	6 hr
Aug 4, 10:39 AM EDT	Mesoscale Discussion	SPC	Allegheny, Beaver, Fayette, Greene, Washington, Westmoreland	2 hr
Aug 4, 11:55 AM EDT	Severe Thunderstorm Watch	SPC	Allegheny, Armstrong, Beaver, Butler, Clarion, Fayette and 8 more	5 hr
Aug 4, 2:30 PM EDT	Severe Thunderstorm Watch	SPC	Bland, Buchanan, Dickenson, Tazewell, Wise	6 hr
Aug 4, 4:39 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Russell, Tazewell, Wise, City of Norton	96 min
Aug 4, 2:01 PM EDT	Mesoscale Discussion	SPC	Boone, Cabell, Kanawha, Lincoln, Logan, Mason and 3 more	89 min

Nearby

Mesoscale Discussions in Pennsylvania, 2004 Mesoscale Discussions in New Jersey, 2004 Mesoscale Discussions in Maryland, 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.