Alert archive / Virginia / Mesoscale Discussions in 2020

Mesoscale Discussion 1673

September 3, 20206 states

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2020, 3:06 PM EDT for 6 states. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Sep 3, 2020, 3:06 PM EDT (19:06 UTC)
Expired: Sep 3, 2020, 5:00 PM EDT
In force: 114 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...tornado watch likely
Chance of a watch: 95%

All 120 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick 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, Somerset County, MD, Talbot County, MD, Washington County, MD, Wicomico County, MD, Worcester County, MD, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Adams County, PA, Chester County, PA, Cumberland County, PA, Delaware County, PA, Franklin County, PA, Fulton County, PA, Lancaster County, PA, Philadelphia County, PA, York County, PA, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Arlington County, VA, Augusta County, VA, Buckingham County, VA, Caroline County, VA, Charles City County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Manassas, VA, City of Manassas Park, VA, City of Petersburg, VA, City of Poquoson, VA, City of Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, City of Williamsburg, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Hanover County, VA, Henrico County, VA, Highland County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Mathews County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Orange County, VA, Page County, VA, Powhatan County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland County, VA, York 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

The radar

The Sterling radar (KLWX), 58 km from the middle of the area, began a volume at 19:09 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.

Tornado Watch 485Sep 3, 3:40 PM EDT

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 7.1 hours before the alert went out and 52 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: 12 J/kg
Mixed-layer CIN: -77 J/kg
Mixed-layer LCL: 1011 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 2 m²/s²
0-3 km storm-relative helicity: 73 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 2, 8:20 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle	115 min
Sep 3, 3:42 PM EDT	Tornado Watch	SPC	Kent, New Castle, Sussex	6 hr
Sep 3, 6:18 PM EDT	Mesoscale Discussion	SPC	Kent, Sussex	117 min

Nearby

Mesoscale Discussions in Virginia, 2020 Mesoscale Discussions in Maryland, 2020 Mesoscale Discussions in Pennsylvania, 2020 Every mesoscale discussion in 2020

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.