Alert archive / Virginia / Mesoscale Discussions in 2020

Mesoscale Discussion 294

April 7, 20206 counties in Maryland; 50 counties in Virginia; 9 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 7, 2020, 2:57 PM EDT for 6 counties in Maryland; 50 counties in Virginia; 9 counties in West Virginia. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued
Apr 7, 2020, 2:57 PM EDT (18:57 UTC)
Expired
Apr 7, 2020, 4:30 PM EDT
In force
93 min
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 65 counties

Calvert County, MD, Charles County, MD, Dorchester County, MD, Saint Mary's County, MD, Somerset County, MD, Wicomico County, MD, Accomack County, VA, 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, Gloucester 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, Lancaster County, VA, Louisa County, VA, Madison County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland 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, Barbour County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Mineral County, WV, Pendleton County, WV, Preston County, WV, Randolph County, WV, Tucker County, WV

The radar

The Sterling radar (KLWX), 80 km from the middle of the area, began a volume at 18:59 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

Roanoke, VA (KRNK), launched 12:00Z, 7.0 hours before the alert went out and 196 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, Roanoke, VA at 12:00Z on 2020-04-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 6 joules per kilogram.LCLLFCEL10008507005003002001001 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, Roanoke, VA at 12:00Z on 2020-04-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 90 square meters per square second.1939587897117Sfc1 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
6 J/kg
Mixed-layer CIN
-225 J/kg
Mixed-layer LCL
1126 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
90 m²/s²
0-3 km storm-relative helicity
81 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.

IssuedProductOfficeCountiesLasted
Apr 7, 2:07 PM EDTMesoscale DiscussionSPCAppomattox, Bedford, Brunswick, Campbell, Charlotte, Dinwiddie and 24 more53 min
Apr 7, 4:57 PM EDTMesoscale DiscussionSPCBarbour, Braxton, Calhoun, Doddridge, Gilmer, Harrison and 16 more63 min
Apr 7, 7:06 PM EDTMesoscale DiscussionSPCBarbour, Doddridge, Harrison, Lewis, Pleasants, Randolph and 5 more84 min

Nearby

Mesoscale Discussions in Virginia, 2020Mesoscale Discussions in West Virginia, 2020Mesoscale Discussions in Maryland, 2020Every 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.