Alert archive / North Carolina / Mesoscale Discussions in 2015

Mesoscale Discussion 411

April 21, 201510 counties in North Carolina; City of Chesapeake, City of Franklin, City of Suffolk, Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2015, 2:33 AM EDT for 10 counties in North Carolina; City of Chesapeake, City of Franklin, City of Suffolk, Virginia. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Apr 21, 2015, 2:33 AM EDT (06:33 UTC)
Expired: Apr 21, 2015, 4:00 AM EDT
In force: 87 min
Issued by: the Storm Prediction Center

Counties Bertie County, NC, Camden County, NC, Chowan County, NC, Edgecombe County, NC, Gates County, NC, Halifax County, NC, Hertford County, NC, Nash County, NC, Pasquotank County, NC, Perquimans County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Suffolk, VA

The radar

The Norfolk radar (KAKQ), 89 km from the middle of the area, began a volume at 06:33 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, 6.6 hours before the alert went out and 166 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: 11 J/kg
Mixed-layer CIN: -238 J/kg
Mixed-layer LCL: 1672 m above ground
0-6 km bulk shear: 43 kt
0-1 km storm-relative helicity: 232 m²/s²
0-3 km storm-relative helicity: 249 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

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 20, 11:37 PM EDT	Mesoscale Discussion	SPC	Chatham, Durham, Franklin, Granville, Halifax, Lee and 5 more	53 min
Apr 21, 12:37 AM EDT	Tornado Watch	SPC	Bertie, Camden, Chowan, Currituck, Edgecombe, Franklin and 14 more	4 hr

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.