Alert archive / North Carolina / Mesoscale Discussions in 2011

Mesoscale Discussion 777

May 13, 201134 counties in North Carolina; 6 counties in South Carolina; 8 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at May 13, 2011, 4:36 PM EDT for 34 counties in North Carolina; 6 counties in South Carolina; 8 counties in Virginia. It was in force for 24 min.

The area

The outline as issued.

The facts

Issued: May 13, 2011, 4:36 PM EDT (20:36 UTC)
Expired: May 13, 2011, 5:00 PM EDT
In force: 24 min
Issued by: the Storm Prediction Center

All 48 counties

Alamance County, NC, Alexander County, NC, Alleghany County, NC, Anson County, NC, Ashe County, NC, Avery County, NC, Burke County, NC, Cabarrus County, NC, Caldwell County, NC, Caswell County, NC, Catawba County, NC, Cleveland County, NC, Davidson County, NC, Davie County, NC, Forsyth County, NC, Gaston County, NC, Guilford County, NC, Iredell County, NC, Lincoln County, NC, McDowell County, NC, Mecklenburg County, NC, Montgomery County, NC, Polk County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Rutherford County, NC, Stanly County, NC, Stokes County, NC, Surry County, NC, Union County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Cherokee County, SC, Chester County, SC, Greenville County, SC, Lancaster County, SC, Spartanburg County, SC, York County, SC, Carroll County, VA, City of Danville, VA, City of Galax, VA, City of Martinsville, VA, Grayson County, VA, Halifax County, VA, Henry County, VA, Patrick County, VA

The radar

The Roanoke radar (KFCX), 102 km from the middle of the area, began a volume at 20:39 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.

Severe Thunderstorm Watch 299May 13, 4:45 PM EDT

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 8.6 hours before the alert went out and 35 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: 185 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 606 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 64 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
May 13, 12:22 PM EDT	Mesoscale Discussion	SPC	Cherokee, Graham, Swain	113 min
May 13, 1:10 PM EDT	Severe Thunderstorm Watch	SPC	Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 15 more	6 hr
May 13, 3:47 PM EDT	Mesoscale Discussion	SPC	Ashe, Avery, Buncombe, Cherokee, Clay, Graham and 11 more	58 min
May 13, 4:44 PM EDT	Severe Thunderstorm Watch	SPC	Alamance, Anson, Cabarrus, Caswell, Catawba, Chatham and 30 more	8 hr
May 13, 7:21 PM EDT	Severe Thunderstorm Watch	SPC	Bladen, Cumberland, Duplin, Edgecombe, Franklin, Greene and 11 more	6 hr

Nearby

Mesoscale Discussions in North Carolina, 2011 Mesoscale Discussions in Virginia, 2011 Mesoscale Discussions in South Carolina, 2011 Every mesoscale discussion in 2011

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.