Alert archive / Virginia / Mesoscale Discussions in 2007

Mesoscale Discussion 818

May 16, 20076 states

The Storm Prediction Center issued this mesoscale discussion at May 16, 2007, 12:56 PM EDT for 6 states. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: May 16, 2007, 12:56 PM EDT (16:56 UTC)
Expired: May 16, 2007, 2:00 PM EDT
In force: 64 min
Issued by: the Storm Prediction Center

All 85 counties

New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Washington County, MD, Bergen County, NJ, Essex County, NJ, Hunterdon County, NJ, Morris County, NJ, Passaic County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Adams County, PA, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Cumberland County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Pike County, PA, Schuylkill County, PA, York County, PA, Albemarle County, VA, Amherst County, VA, Arlington County, VA, Augusta County, VA, Buckingham County, VA, Caroline County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Lexington, 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, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, King George 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, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 70 km from the middle of the area, began a volume at 16:56 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 278May 16, 1:30 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 4.9 hours before the alert went out and 67 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: 25 J/kg
Mixed-layer CIN: -213 J/kg
Mixed-layer LCL: 1324 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 135 m²/s²
0-3 km storm-relative helicity: 160 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 16, 1:26 PM EDT	Severe Thunderstorm Watch	SPC	Kent, New Castle, Sussex	7 hr
May 16, 3:46 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	89 min
May 16, 11:57 AM EDT	Mesoscale Discussion	SPC	Bergen, Morris, Passaic, Sussex, Warren	93 min
May 16, 12:46 AM EDT	Mesoscale Discussion	SPC	Allegheny, Beaver, Butler, Lawrence, Washington	59 min

Nearby

Mesoscale Discussions in Virginia, 2007 Mesoscale Discussions in Pennsylvania, 2007 Mesoscale Discussions in Maryland, 2007 Every mesoscale discussion in 2007

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.