Alert archive / North Carolina / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 502

June 18, 201123 counties in North Carolina; 11 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Jun 18, 2011, 3:38 PM EDT for 23 counties in North Carolina; 11 counties in Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Jun 18, 2011, 3:38 PM EDT (19:38 UTC)
Expired: Jun 18, 2011, 7:48 PM EDT
In force: 4 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 34 counties

Alamance County, NC, Anson County, NC, Caswell County, NC, Chatham County, NC, Davidson County, NC, Durham County, NC, Forsyth County, NC, Granville County, NC, Guilford County, NC, Harnett County, NC, Hoke County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Rockingham County, NC, Scotland County, NC, Stanly County, NC, Stokes County, NC, Wake County, NC, Carroll County, VA, Charlotte County, VA, City of Danville, VA, City of Galax, VA, City of Martinsville, VA, Floyd County, VA, Franklin County, VA, Halifax County, VA, Henry County, VA, Patrick County, VA, Pittsylvania County, VA

The radar

The Roanoke radar (KFCX), 108 km from the middle of the area, began a volume at 19:38 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes: 5%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 10%
One or more hailstones of 2 inches or more: 5%
Six or more combined severe hail and wind reports: 60%

Warnings issued inside it

17 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jun 18, 4:21 PM EDT	Severe Thunderstorm Warning	RNK	Carroll, Floyd, Patrick	39 min
Jun 18, 4:43 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth, Guilford	40 min
Jun 18, 4:43 PM EDT	Severe Thunderstorm Warning	RAH	Stanly	47 min
Jun 18, 4:48 PM EDT	Severe Thunderstorm Warning	RAH	Davidson, Guilford, Montgomery, Randolph	57 min
Jun 18, 4:58 PM EDT	Severe Thunderstorm Warning	RAH	Anson	62 min
Jun 18, 5:02 PM EDT	Severe Thunderstorm Warning	RAH	Alamance, Guilford	58 min
Jun 18, 5:12 PM EDT	Severe Thunderstorm Warning	RAH	Richmond	63 min
Jun 18, 5:12 PM EDT	Severe Thunderstorm Warning	RNK	Bedford, Franklin, Pittsylvania, Roanoke, City of Roanoke	63 min
Jun 18, 5:19 PM EDT	Severe Thunderstorm Warning	RAH	Chatham, Lee, Moore, Randolph	56 min
Jun 18, 5:27 PM EDT	Severe Thunderstorm Warning	RAH	Stanly	16 min
Jun 18, 5:55 PM EDT	Severe Thunderstorm Warning	RAH	Alamance, Durham, Orange, Person	50 min
Jun 18, 5:58 PM EDT	Severe Thunderstorm Warning	RAH	Hoke, Scotland	49 min
Jun 18, 6:07 PM EDT	Severe Thunderstorm Warning	RNK	Amherst, Appomattox, Bedford, Campbell, Pittsylvania, City of Lynchburg	53 min
Jun 18, 6:11 PM EDT	Severe Thunderstorm Warning	RAH	Chatham, Harnett, Lee, Wake	64 min
Jun 18, 6:39 PM EDT	Severe Thunderstorm Warning	RAH	Durham, Granville, Person, Wake	51 min
Jun 18, 7:06 PM EDT	Severe Thunderstorm Warning	RAH	Johnston, Wake	54 min
Jun 18, 7:14 PM EDT	Severe Thunderstorm Warning	RAH	Franklin, Granville, Vance, Warren	61 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 7.6 hours before the alert went out and 45 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: 166 J/kg
Mixed-layer CIN: -76 J/kg
Mixed-layer LCL: 1389 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: -56 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 18, 9:38 AM EDT	Mesoscale Discussion	SPC	Buncombe, Cherokee, Clay, Graham, Haywood, Henderson and 5 more	97 min
Jun 18, 11:05 AM EDT	Severe Thunderstorm Watch	SPC	Alexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 24 more	9 hr
Jun 18, 2:21 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Ashe, Burke, Caldwell, Catawba and 18 more	84 min
Jun 18, 5:46 PM EDT	Mesoscale Discussion	SPC	Alamance, Anson, Caswell, Chatham, Cumberland, Durham and 19 more	59 min
Jun 18, 7:20 PM EDT	Severe Thunderstorm Watch	SPC	Bladen, Brunswick, Columbus, New Hanover, Pender, Robeson	5 hr
Jun 18, 3:55 PM EDT	Mesoscale Discussion	SPC	Abbeville, Aiken, Calhoun, Edgefield, Fairfield, Greenwood and 6 more	35 min
Jun 18, 4:08 PM EDT	Severe Thunderstorm Watch	SPC	Abbeville, Aiken, Bamberg, Barnwell, Calhoun, Chesterfield and 14 more	6 hr
Jun 18, 6:49 PM EDT	Mesoscale Discussion	SPC	Abbeville, Aiken, Allendale, Anderson, Bamberg, Barnwell and 21 more	86 min

Nearby

Severe Thunderstorm Watches in North Carolina, 2011 Severe Thunderstorm Watches in Virginia, 2011 Every severe thunderstorm watch 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.