Alert archive / Virginia / Mesoscale Discussions in 2018

Mesoscale Discussion 273

April 15, 201810 counties in North Carolina; 23 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 15, 2018, 6:28 PM EDT for 10 counties in North Carolina; 23 counties in Virginia. It was in force for 62 min.

The area

The outline as issued.

The facts

Issued: Apr 15, 2018, 6:28 PM EDT (22:28 UTC)
Expired: Apr 15, 2018, 7:30 PM EDT
In force: 62 min
Issued by: the Storm Prediction Center

All 33 counties

Cumberland County, NC, Franklin County, NC, Granville County, NC, Halifax County, NC, Johnston County, NC, Nash County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wilson County, NC, Amelia County, VA, Brunswick County, VA, Buckingham County, VA, Charlotte County, VA, Chesterfield County, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Hopewell, VA, City of Petersburg, VA, City of Richmond, VA, Cumberland County, VA, Dinwiddie County, VA, Fluvanna County, VA, Goochland County, VA, Greensville County, VA, Hanover County, VA, Henrico County, VA, Louisa County, VA, Lunenburg County, VA, Mecklenburg County, VA, Nottoway County, VA, Powhatan County, VA, Prince Edward County, VA

The radar

The Norfolk radar (KAKQ), 79 km from the middle of the area, began a volume at 22:30 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 55Apr 15, 9:35 PM EDT

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 10.5 hours before the alert went out and 145 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 881 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 143 m²/s²
0-3 km storm-relative helicity: 148 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 15, 11:15 AM EDT	Mesoscale Discussion	SPC	Alexander, Anson, Cabarrus, Catawba, Davidson, Davie and 11 more	2 hr
Apr 15, 12:13 PM EDT	Tornado Watch	SPC	Alexander, Alleghany, Ashe, Burke, Cabarrus, Caldwell and 16 more	9 hr
Apr 15, 2:29 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Caswell, Chatham, Cumberland, Davidson and 20 more	91 min
Apr 15, 3:02 PM EDT	Tornado Watch	SPC	Alamance, Anson, Bladen, Brunswick, Caswell, Chatham and 34 more	8 hr
Apr 15, 3:17 PM EDT	Mesoscale Discussion	SPC	Anson, Cabarrus, Davidson, Davie, Forsyth, Rowan and 3 more	88 min
Apr 15, 5:45 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Cabarrus, Caswell, Chatham, Cumberland and 24 more	90 min
Apr 15, 6:14 PM EDT	Tornado Watch	SPC	Amelia, Brunswick, Chesterfield, Cumberland, Dinwiddie, Fluvanna and 8 more	7 hr

Nearby

Mesoscale Discussions in Virginia, 2018 Mesoscale Discussions in North Carolina, 2018 Every mesoscale discussion in 2018

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.