Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 454

April 23, 200416 counties in Maryland; 30 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 23, 2004, 6:30 PM EDT for 16 counties in Maryland; 30 counties in Virginia. It was in force for 30 min.

The area

The outline as issued.

The facts

Issued: Apr 23, 2004, 6:30 PM EDT (22:30 UTC)
Expired: Apr 23, 2004, 7:00 PM EDT
In force: 30 min
Issued by: the Storm Prediction Center

All 46 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Talbot County, MD, Arlington County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Colonial Heights, VA, City of Falls Church, VA, City of Hopewell, VA, City of Petersburg, VA, City of Poquoson, VA, City of Richmond, VA, City of Williamsburg, VA, Dinwiddie County, VA, Essex County, VA, Gloucester County, VA, Henrico County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Prince George County, VA, Richmond County, VA, Surry County, VA, Westmoreland County, VA, York County, VA

The radar

The Sterling radar (KLWX), 94 km from the middle of the area, began a volume at 22:33 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.5 hours before the alert went out and 87 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: 967 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 78 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
Apr 23, 2:03 PM EDT	Mesoscale Discussion	SPC	Carroll, Charles, Frederick, Howard, Montgomery, Prince George's and 2 more	2 hr
Apr 23, 2:40 PM EDT	Severe Thunderstorm Watch	SPC	Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 15 more	4 hr

Nearby

Mesoscale Discussions in Virginia, 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; radar from the NEXRAD Level II archive.