Alert archive / Virginia / Mesoscale Discussions in 2020

Mesoscale Discussion 306

April 8, 20206 counties in Maryland; 17 counties in Virginia; Hardy County, Jefferson County, West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 8, 2020, 3:53 AM EDT for 6 counties in Maryland; 17 counties in Virginia; Hardy County, Jefferson County, West Virginia. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Apr 8, 2020, 3:53 AM EDT (07:53 UTC)
Expired: Apr 8, 2020, 5:30 AM EDT
In force: 97 min
Issued by: the Storm Prediction Center

All 25 counties

Carroll County, MD, City of Baltimore, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Shenandoah County, VA, Warren County, VA, Hardy County, WV, Jefferson County, WV

The radar

The Sterling radar (KLWX), 42 km from the middle of the area, began a volume at 07:55 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 00:00Z, 7.9 hours before the alert went out and 50 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: 14 J/kg
Mixed-layer CIN: -214 J/kg
Mixed-layer LCL: 1167 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 76 m²/s²
0-3 km storm-relative helicity: 118 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
Apr 7, 11:40 PM EDT	Severe Thunderstorm Watch	SPC	Garrett	6 hr
Apr 8, 1:52 AM EDT	Mesoscale Discussion	SPC	Allegany, Garrett	83 min
Apr 8, 2:14 AM EDT	Severe Thunderstorm Watch	SPC	Allegany, Washington	2 hr
Apr 8, 5:30 AM EDT	Mesoscale Discussion	SPC	Bath, Highland	30 min
Apr 8, 12:39 PM EDT	Mesoscale Discussion	SPC	Bland, Buchanan, Craig, Giles, Montgomery, Pulaski and 3 more	96 min
Apr 8, 1:10 PM EDT	Severe Thunderstorm Watch	SPC	Bland, Buchanan, Carroll, Craig, Dickenson, Floyd and 19 more	7 hr
Apr 8, 4:05 PM EDT	Mesoscale Discussion	SPC	Bedford, Bland, Buchanan, Carroll, Craig, Dickenson and 20 more	85 min
Apr 8, 6:06 PM EDT	Mesoscale Discussion	SPC	City of Danville	84 min
Apr 7, 10:04 PM EDT	Mesoscale Discussion	SPC	Hancock	86 min
Apr 8, 3:16 AM EDT	Mesoscale Discussion	SPC	Barbour, Braxton, Calhoun, Doddridge, Gilmer, Harrison and 13 more	89 min

Nearby

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