Alert archive / Virginia / Mesoscale Discussions in 2004

Mesoscale Discussion 740

May 18, 20046 counties in Maryland; 44 counties in Virginia; 5 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at May 18, 2004, 1:14 PM EDT for 6 counties in Maryland; 44 counties in Virginia; 5 counties in West Virginia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 18, 2004, 1:14 PM EDT (17:14 UTC)
Expired: May 18, 2004, 3:15 PM EDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 55 counties

Calvert County, MD, Charles County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Albemarle County, VA, Arlington County, VA, Augusta County, VA, Caroline County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, 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, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Highland County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, Berkeley County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Pendleton County, WV

The radar

The Sterling radar (KLWX), 72 km from the middle of the area, began a volume at 17:17 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, 5.2 hours before the alert went out and 75 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: 156 J/kg
Mixed-layer CIN: -180 J/kg
Mixed-layer LCL: 979 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 153 m²/s²
0-3 km storm-relative helicity: 134 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 18, 2:54 PM EDT	Mesoscale Discussion	SPC	Allegany, Carroll, Cecil, Harford, Washington	96 min
May 18, 7:49 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Caroline, Carroll, Cecil, Frederick and 8 more	2 hr
May 18, 12:54 PM EDT	Mesoscale Discussion	SPC	Brooke, Hancock, Marshall, Ohio	66 min
May 18, 1:45 PM EDT	Severe Thunderstorm Watch	SPC	Brooke, Doddridge, Hancock, Harrison, Marion, Marshall and 8 more	6 hr
May 18, 4:02 PM EDT	Mesoscale Discussion	SPC	Brooke, Ohio	118 min
May 18, 7:09 PM EDT	Mesoscale Discussion	SPC	Brooke, Doddridge, Hancock, Harrison, Marion, Marshall and 9 more	96 min

Nearby

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