Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 449

April 23, 20048 counties in Maryland; 60 counties in Virginia; 11 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 23, 2004, 2:03 PM EDT for 8 counties in Maryland; 60 counties in Virginia; 11 counties in West Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 23, 2004, 2:03 PM EDT (18:03 UTC)
Expired
Apr 23, 2004, 4:30 PM EDT
In force
2 hr
Issued by
the Storm Prediction Center
All 79 counties

Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Washington County, MD, Albemarle County, VA, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Montgomery County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Prince Edward County, VA, Prince William County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford 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, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Tucker County, WV

The radar

The Sterling radar (KLWX), 118 km from the middle of the area, began a volume at 18:07 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.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.1 hours before the alert went out and 124 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-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2004-04-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2004-04-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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.

IssuedProductOfficeCountiesLasted
Apr 23, 2:40 PM EDTSevere Thunderstorm WatchSPCAnne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 15 more4 hr
Apr 23, 6:30 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 10 more30 min

Nearby

Mesoscale Discussions in Virginia, 2004Mesoscale Discussions in West Virginia, 2004Mesoscale Discussions in Maryland, 2004Every 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.