Alert archive / Virginia / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 344

May 23, 201147 counties in North Carolina; 84 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at May 23, 2011, 3:16 PM EDT for 47 counties in North Carolina; 84 counties in Virginia. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: May 23, 2011, 3:16 PM EDT (19:16 UTC)
Expired: May 23, 2011, 10:20 PM EDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 131 counties

Alamance County, NC, Alexander County, NC, Alleghany County, NC, Ashe County, NC, Avery County, NC, Bertie County, NC, Burke County, NC, Caldwell County, NC, Camden County, NC, Caswell County, NC, Catawba County, NC, Chatham County, NC, Chowan County, NC, Currituck County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Hertford County, NC, Iredell County, NC, McDowell County, NC, Mitchell County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Pasquotank County, NC, Perquimans County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Watauga County, NC, Wilkes County, NC, Wilson County, NC, Yadkin County, NC, Yancey County, NC, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Carroll County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Covington, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Galax, VA, City of Hampton, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Radford, VA, City of Richmond, VA, City of Roanoke, VA, City of Salem, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Craig County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Gloucester County, VA, Goochland County, VA, Grayson County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lancaster County, VA, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Montgomery County, VA, New Kent County, VA, Northumberland County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Pulaski County, VA, Richmond County, VA, Roanoke County, VA, Rockbridge County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, Wythe County, VA, York County, VA

The radar

The Roanoke radar (KFCX), 89 km from the middle of the area, began a volume at 19:19 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 70%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
May 23, 3:36 PM EDT	Severe Thunderstorm Warning	GSP	McDowell, Rutherford	27 min
May 23, 3:45 PM EDT	Flash Flood Warning	RNK	Ashe, Watauga, Wilkes	4 hr
May 23, 3:56 PM EDT	Severe Thunderstorm Warning	RNK	Surry, Wilkes, Yadkin	64 min
May 23, 4:14 PM EDT	Severe Thunderstorm Warning	RNK	Surry, Wilkes	46 min
May 23, 4:41 PM EDT	Severe Thunderstorm Warning	GSP	Davie, Iredell	64 min
May 23, 5:21 PM EDT	Severe Thunderstorm Warning	RAH	Davidson	24 min
May 23, 6:07 PM EDT	Severe Thunderstorm Warning	AKQ	Northampton	38 min
May 23, 6:13 PM EDT	Severe Thunderstorm Warning	AKQ	Northampton	47 min
May 23, 6:14 PM EDT	Severe Thunderstorm Warning	RAH	Halifax	16 min
May 23, 6:39 PM EDT	Severe Thunderstorm Warning	AKQ	Southampton, Surry, Sussex	21 min
May 23, 6:41 PM EDT	Severe Thunderstorm Warning	RNK	Amherst, Appomattox, Buckingham	52 min
May 23, 6:50 PM EDT	Severe Thunderstorm Warning	AKQ	Gates, Hertford, Northampton	40 min
May 23, 7:04 PM EDT	Severe Thunderstorm Warning	RAH	Halifax	26 min
May 23, 7:12 PM EDT	Severe Thunderstorm Warning	AKQ	Northampton	33 min
May 23, 7:17 PM EDT	Severe Thunderstorm Warning	AKQ	Gates, Hertford, Northampton	43 min
May 23, 7:48 PM EDT	Tornado Warning	AKQ	Hertford	27 min
May 23, 7:55 PM EDT	Severe Thunderstorm Warning	AKQ	Bertie	50 min
May 23, 8:02 PM EDT	Severe Thunderstorm Warning	RAH	Edgecombe	28 min
May 23, 8:02 PM EDT	Severe Thunderstorm Warning	AKQ	Isle of Wight, City of Chesapeake, City of Hampton, City of Newport News, City of Norfolk, City of Portsmouth and 2 more	28 min
May 23, 8:16 PM EDT	Severe Thunderstorm Warning	AKQ	Bertie, Chowan, Hertford, Perquimans	30 min
May 23, 8:19 PM EDT	Tornado Warning	AKQ	Bertie	26 min
May 23, 8:26 PM EDT	Severe Thunderstorm Warning	RAH	Edgecombe, Halifax	49 min
May 23, 8:27 PM EDT	Severe Thunderstorm Warning	AKQ	City of Norfolk, City of Portsmouth, City of Virginia Beach	33 min
May 23, 8:45 PM EDT	Severe Thunderstorm Warning	AKQ	Bertie	45 min
May 23, 9:18 PM EDT	Severe Thunderstorm Warning	RAH	Edgecombe	27 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

Roanoke, VA (KRNK), launched 12:00Z, 7.3 hours before the alert went out and 32 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: 264 J/kg
Mixed-layer CIN: -138 J/kg
Mixed-layer LCL: 632 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 181 m²/s²
0-3 km storm-relative helicity: 183 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

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
May 22, 9:02 PM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Catawba, Surry, Wilkes, Yadkin	58 min
May 23, 2:33 PM EDT	Mesoscale Discussion	SPC	Alamance, Caswell, Chatham, Davidson, Durham, Forsyth and 9 more	87 min
May 23, 7:02 PM EDT	Mesoscale Discussion	SPC	Alamance, Caswell, Chatham, Davidson, Davie, Durham and 17 more	58 min
May 23, 10:33 AM EDT	Mesoscale Discussion	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 26 more	87 min
May 23, 10:48 AM EDT	Severe Thunderstorm Watch	SPC	Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 28 more	9 hr
May 23, 4:40 PM EDT	Mesoscale Discussion	SPC	Arlington, Clarke, Culpeper, Fairfax, Fauquier, Loudoun and 8 more	95 min

Nearby

Severe Thunderstorm Watches in Virginia, 2011 Severe Thunderstorm Watches in North Carolina, 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.