Alert archive / West Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 802

May 21, 20044 counties in Maryland; 30 counties in Virginia; 36 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at May 21, 2004, 5:31 PM EDT for 4 counties in Maryland; 30 counties in Virginia; 36 counties in West Virginia. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
May 21, 2004, 5:31 PM EDT (21:31 UTC)
Expired
May 21, 2004, 7:00 PM EDT
In force
89 min
Issued by
the Storm Prediction Center
All 70 counties

Allegany County, MD, Frederick County, MD, Garrett County, MD, Washington County, MD, Albemarle County, VA, Alleghany County, VA, Augusta County, VA, Bath County, VA, City of Charlottesville, VA, City of Covington, VA, City of Fairfax, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Warren County, VA, Barbour County, WV, Berkeley County, WV, Boone County, WV, Braxton County, WV, Calhoun County, WV, Clay County, WV, Fayette County, WV, Gilmer County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Harrison County, WV, Jackson County, WV, Jefferson County, WV, Kanawha County, WV, Lewis County, WV, Lincoln County, WV, Mason County, WV, Mineral County, WV, Monroe County, WV, Morgan County, WV, Nicholas County, WV, Pendleton County, WV, Pocahontas County, WV, Preston County, WV, Putnam County, WV, Raleigh County, WV, Randolph County, WV, Roane County, WV, Summers County, WV, Taylor County, WV, Tucker County, WV, Upshur County, WV, Webster County, WV, Wirt County, WV

The radar

The Sterling radar (KLWX), 162 km from the middle of the area, began a volume at 21:32 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

Pittsburgh, PA (KPIT), launched 12:00Z, 9.5 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-pSkew-T log-p diagram, Pittsburgh, PA at 12:00Z on 2004-05-21Temperature 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, Pittsburgh, PA at 12:00Z on 2004-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -197 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
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.

IssuedProductOfficeCountiesLasted
May 21, 8:34 AM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Carroll, Charles, Frederick, Howard and 4 more86 min
May 21, 12:28 PM EDTMesoscale DiscussionSPCCharles, Saint Mary's2 hr
May 21, 6:35 PM EDTSevere Thunderstorm WatchSPCAllegany, Carroll, Charles, Frederick, Garrett, Howard and 3 more4 hr
May 21, 1:00 PM EDTSevere Thunderstorm WatchSPCAccomack, Albemarle, Amelia, Amherst, Appomattox, Augusta and 68 more7 hr
May 21, 4:30 PM EDTMesoscale DiscussionSPCAmelia, Brunswick, Charles City, Charlotte, Chesterfield, Cumberland and 38 more2 hr
May 21, 2:40 AM EDTMesoscale DiscussionSPCHancock65 min
May 21, 4:45 AM EDTMesoscale DiscussionSPCBrooke, Hancock, Marshall, Ohio, Wetzel60 min
May 21, 2:19 PM EDTMesoscale DiscussionSPCHancock116 min
May 21, 3:15 PM EDTSevere Thunderstorm WatchSPCBrooke, Hancock, Ohio6 hr

Nearby

Mesoscale Discussions in West Virginia, 2004Mesoscale Discussions in 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.