Alert archive / Pennsylvania / Mesoscale Discussions in 2003

Mesoscale Discussion 819

May 7, 20034 states

The Storm Prediction Center issued this mesoscale discussion at May 7, 2003, 12:49 PM EDT for 4 states. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: May 7, 2003, 12:49 PM EDT (16:49 UTC)
Expired: May 7, 2003, 2:45 PM EDT
In force: 116 min
Issued by: the Storm Prediction Center

All 61 counties

Allegany County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Frederick County, MD, Garrett County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Adams County, PA, Armstrong County, PA, Bedford County, PA, Berks County, PA, Blair County, PA, Cambria County, PA, Cameron County, PA, Centre County, PA, Clarion County, PA, Clearfield County, PA, Clinton County, PA, Columbia County, PA, Cumberland County, PA, Dauphin County, PA, Fayette County, PA, Franklin County, PA, Fulton County, PA, Huntingdon County, PA, Indiana County, PA, Jefferson County, PA, Juniata County, PA, Lancaster County, PA, Lebanon County, PA, Lycoming County, PA, Mifflin County, PA, Montour County, PA, Northumberland County, PA, Perry County, PA, Schuylkill County, PA, Snyder County, PA, Somerset County, PA, Sullivan County, PA, Union County, PA, Westmoreland County, PA, York County, PA, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Loudoun County, VA, Shenandoah County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Preston County, WV, Tucker County, WV

The radar

The State College radar (KCCX), 69 km from the middle of the area, began a volume at 16:50 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 286May 7, 1:20 PM EDT

The nearest sounding before it

Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 4.8 hours before the alert went out and 187 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: 11 J/kg
Mixed-layer CIN: -276 J/kg
Mixed-layer LCL: 815 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 13 m²/s²
0-3 km storm-relative helicity: 8 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 7, 1:20 PM EDT	Severe Thunderstorm Watch	SPC	Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 7 more	6 hr
May 7, 3:21 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Calvert, Carroll, Charles, Frederick and 6 more	114 min
May 7, 6:07 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more	53 min
May 7, 3:40 AM EDT	Severe Thunderstorm Watch	SPC	Lee	5 hr
May 7, 5:26 AM EDT	Mesoscale Discussion	SPC	Lee	2 hr

Nearby

Mesoscale Discussions in Pennsylvania, 2003 Mesoscale Discussions in Maryland, 2003 Mesoscale Discussions in West Virginia, 2003 Every mesoscale discussion in 2003

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.