Alert archive / North Carolina / Mesoscale Discussions in 2015

Mesoscale Discussion 392

April 20, 201522 counties in North Carolina; 8 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2015, 2:25 AM EDT for 22 counties in North Carolina; 8 counties in Virginia. It was in force for 95 min.

The area

The outline as issued.

The facts

Issued: Apr 20, 2015, 2:25 AM EDT (06:25 UTC)
Expired: Apr 20, 2015, 4:00 AM EDT
In force: 95 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

All 30 counties

Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Craven County, NC, Currituck County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Hyde County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Northampton County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Washington County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Hampton, VA, City of Norfolk, VA, City of Portsmouth, VA, City of Suffolk, VA, Isle of Wight County, VA, Southampton County, VA

The radar

The Norfolk radar (KAKQ), 106 km from the middle of the area, began a volume at 06:28 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

Newport, NC (KMHX), launched 00:00Z, 6.4 hours before the alert went out and 140 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: 202 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 586 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 80 m²/s²
0-3 km storm-relative helicity: 224 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.8

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
Apr 19, 9:06 PM EDT	Mesoscale Discussion	SPC	Bladen, Brunswick, Duplin, Durham, Edgecombe, Franklin and 13 more	54 min
Apr 20, 1:03 PM EDT	Mesoscale Discussion	SPC	Alexander, Anson, Buncombe, Burke, Cabarrus, Caldwell and 20 more	57 min
Apr 20, 1:23 PM EDT	Tornado Watch	SPC	Alexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 20 more	7 hr
Apr 20, 1:54 PM EDT	Mesoscale Discussion	SPC	Alleghany, Stokes, Surry	3 hr
Apr 20, 2:55 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Alleghany, Anson, Ashe, Bertie, Caswell and 33 more	7 hr
Apr 20, 4:18 PM EDT	Mesoscale Discussion	SPC	Alexander, Buncombe, Burke, Cabarrus, Caldwell, Catawba and 12 more	57 min
Apr 20, 6:27 PM EDT	Mesoscale Discussion	SPC	Alamance, Alleghany, Caswell, Chatham, Durham, Forsyth and 16 more	93 min
Apr 20, 6:45 PM EDT	Mesoscale Discussion	SPC	Alexander, Anson, Avery, Buncombe, Burke, Caldwell and 15 more	60 min
Apr 20, 3:08 PM EDT	Tornado Watch	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 27 more	9 hr
Apr 20, 5:01 PM EDT	Mesoscale Discussion	SPC	Albemarle, Arlington, Augusta, Caroline, Clarke, Culpeper and 30 more	119 min

Nearby

Mesoscale Discussions in North Carolina, 2015 Mesoscale Discussions in Virginia, 2015 Every mesoscale discussion in 2015

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.