Alert archive / Virginia / Tornado Watches in 2011

Tornado Watch 247

April 28, 20115 states

The Storm Prediction Center issued this tornado watch at Apr 28, 2011, 12:41 AM EDT for 5 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Apr 28, 2011, 12:41 AM EDT (04:41 UTC)
Expired: Apr 28, 2011, 7:41 AM EDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 134 counties

Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Alamance County, NC, Alleghany County, NC, Ashe County, NC, Caswell County, NC, Davidson County, NC, Forsyth County, NC, Guilford County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Carter County, TN, Greene County, TN, Hawkins County, TN, Johnson County, TN, Sullivan County, TN, Unicoi County, TN, Washington County, TN, Albemarle County, VA, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Alexandria, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Danville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Galax, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Giles County, VA, Goochland County, VA, Grayson County, VA, Greene County, VA, Halifax County, VA, Henry County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Montgomery County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Pulaski County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Russell County, VA, Scott County, VA, Shenandoah County, VA, Smyth County, VA, Spotsylvania County, VA, Stafford County, VA, Tazewell County, VA, Warren County, VA, Washington County, VA, Wythe County, VA, Berkeley County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mercer County, WV, Mineral County, WV, Monroe County, WV, Morgan County, WV, Pendleton County, WV, Pocahontas County, WV, Summers County, WV

The radar

The Sterling radar (KLWX), 167 km from the middle of the area, began a volume at 04:42 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: 40%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 30%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 40%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 70%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Apr 28, 12:42 AM EDT	Tornado Warning	LWX	Grant, Hampshire, Hardy, Mineral	28 min
Apr 28, 12:45 AM EDT	Tornado Warning	RNK	Bland, Giles, Montgomery, Pulaski, Wythe, City of Radford	45 min
Apr 28, 12:48 AM EDT	Flash Flood Warning	RNK	Alleghany, Bath, Craig, Giles, City of Covington	6 hr
Apr 28, 12:51 AM EDT	Tornado Warning	MRX	Johnson, Sullivan	39 min
Apr 28, 1:03 AM EDT	Severe Thunderstorm Warning	RNK	Alleghany, Bath, Rockbridge, City of Covington	57 min
Apr 28, 1:09 AM EDT	Severe Thunderstorm Warning	LWX	Augusta, Highland, Rockingham	66 min
Apr 28, 1:12 AM EDT	Tornado Warning	RNK	Bland, Smyth, Tazewell, Wythe	33 min
Apr 28, 1:18 AM EDT	Tornado Warning	LWX	Allegany	27 min
Apr 28, 1:19 AM EDT	Tornado Warning	RNK	Craig, Giles, Montgomery, Roanoke	26 min
Apr 28, 1:20 AM EDT	Tornado Warning	RNK	Bland, Smyth, Tazewell, Wythe	25 min
Apr 28, 1:28 AM EDT	Severe Thunderstorm Warning	RNK	Alleghany, Botetourt, Rockbridge, City of Lexington	21 min
Apr 28, 1:29 AM EDT	Severe Thunderstorm Warning	LWX	Allegany, Washington	35 min
Apr 28, 1:33 AM EDT	Flash Flood Warning	LWX	Allegany, Washington	4 hr
Apr 28, 1:34 AM EDT	Tornado Warning	RNK	Alleghany, Bath, Botetourt, Rockbridge, City of Lexington	41 min
Apr 28, 1:39 AM EDT	Flash Flood Warning	RNK	Bland	3 hr
Apr 28, 1:43 AM EDT	Tornado Warning	RNK	Alleghany, Botetourt, Craig, Montgomery	19 min
Apr 28, 1:45 AM EDT	Tornado Warning	RNK	Greenbrier, Mercer, Monroe, Summers	31 min
Apr 28, 1:47 AM EDT	Tornado Warning	RNK	Bland, Giles, Tazewell, Wythe	9 min
Apr 28, 2:07 AM EDT	Tornado Warning	LWX	Augusta, City of Staunton	42 min
Apr 28, 2:10 AM EDT	Severe Thunderstorm Warning	LWX	Frederick, Page, Rockingham, Shenandoah, Warren	65 min
Apr 28, 2:17 AM EDT	Tornado Warning	RNK	Craig, Giles	28 min
Apr 28, 2:24 AM EDT	Tornado Warning	LWX	Shenandoah	25 min
Apr 28, 2:53 AM EDT	Tornado Warning	LWX	Page, Rockingham, Shenandoah, City of Harrisonburg	36 min
Apr 28, 2:59 AM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	62 min
Apr 28, 3:04 AM EDT	Flash Flood Warning	LWX	Washington	7 hr
Apr 28, 3:19 AM EDT	Tornado Warning	LWX	Augusta, City of Staunton	41 min
Apr 28, 3:22 AM EDT	Flash Flood Warning	RNK	Alleghany, Botetourt, Craig, Franklin, Montgomery, Roanoke and 2 more	4 hr
Apr 28, 3:23 AM EDT	Tornado Warning	LWX	Clarke, Frederick, Page, Shenandoah, Warren	39 min
Apr 28, 3:30 AM EDT	Severe Thunderstorm Warning	RAH	Davidson, Forsyth, Guilford, Randolph	60 min
Apr 28, 3:40 AM EDT	Tornado Warning	RNK	Surry, Wilkes, Yadkin	34 min
Apr 28, 3:47 AM EDT	Tornado Warning	RNK	Surry, Wilkes, Yadkin	27 min
Apr 28, 3:50 AM EDT	Tornado Warning	LWX	Page, Rockingham, Shenandoah, City of Harrisonburg	40 min
Apr 28, 3:54 AM EDT	Tornado Warning	LWX	Clarke, Frederick, City of Winchester	34 min
Apr 28, 4:17 AM EDT	Severe Thunderstorm Warning	RNK	Caswell, Rockingham	30 min
Apr 28, 4:24 AM EDT	Tornado Warning	LWX	Carroll, Frederick, Washington	51 min
Apr 28, 4:26 AM EDT	Tornado Warning	LWX	Fauquier, Page, Rappahannock, Warren	23 min
Apr 28, 4:44 AM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Culpeper, Greene, Madison, Orange, Rappahannock and 1 more	46 min
Apr 28, 5:32 AM EDT	Flash Flood Warning	RNK	Alleghany	3 hr
Apr 28, 5:35 AM EDT	Tornado Warning	LWX	Frederick	26 min
Apr 28, 5:43 AM EDT	Tornado Warning	LWX	Frederick	18 min
Apr 28, 5:50 AM EDT	Tornado Warning	LWX	Culpeper, Fauquier, Prince William, Rappahannock	40 min
Apr 28, 5:51 AM EDT	Severe Thunderstorm Warning	RNK	Stokes, Surry	54 min
Apr 28, 6:24 AM EDT	Severe Thunderstorm Warning	RNK	Alleghany, Surry, Wilkes, Yadkin	35 min
Apr 28, 6:37 AM EDT	Tornado Warning	LWX	Frederick, Montgomery	38 min
Apr 28, 6:48 AM EDT	Severe Thunderstorm Warning	RNK	Surry	24 min
Apr 28, 7:05 AM EDT	Tornado Warning	LWX	Carroll, Frederick, Howard, Montgomery	25 min
Apr 28, 7:17 AM EDT	Tornado Warning	LWX	Carroll, Frederick	28 min
Apr 28, 7:27 AM EDT	Flash Flood Warning	LWX	Carroll, Frederick, Howard, Montgomery	5 hr

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 00:00Z, 4.7 hours before the alert went out and 122 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: 372 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1272 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 226 m²/s²
0-3 km storm-relative helicity: 335 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 3.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

019 
WWUS20 KWNS 280441
SEL7
SPC WW 280441
DCZ000-MDZ000-NCZ000-TNZ000-VAZ000-WVZ000-CWZ000-281200-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 247
NWS STORM PREDICTION CENTER NORMAN OK
1240 AM EDT THU APR 28 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

       DISTRICT OF COLUMBIA
       MARYLAND
       NORTHERN NORTH CAROLINA
       FAR NORTHEAST TENNESSEE
       VIRGINIA
       EASTERN WEST VIRGINIA
       COASTAL WATERS

EFFECTIVE THIS THURSDAY MORNING FROM 1240 AM UNTIL 800 AM EDT.

TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHEAST OF
MARTINSBURG WEST VIRGINIA TO 50 MILES WEST OF GREENSBORO NORTH
CAROLINA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 238...WW 239...WW
240...WW 241...WW 242...WW 244...WW 245...WW 246...

DISCUSSION...TSTMS CURRENTLY CRESTING THE BLUE RIDGE ARE EXPECTED TO
INTENSIFY DURING THE EARLY MORNING HOURS AS THEY ENCOUNTER A MOIST
AND MODERATELY UNSTABLE AIR MASS IN PLACE ACROSS THE PIEDMONT.
GIVEN THE STRONG VERTICAL SHEAR IN PLACE...THE SETUP WILL FAVOR A
CONTINUATION OF SUPERCELLS AND BOWING STRUCTURES CAPABLE OF
TORNADOES...DAMAGING WINDS AND HAIL.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
400. MEAN STORM MOTION VECTOR 23045.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 27, 8:15 PM EDT	Severe Thunderstorm Watch	SPC	Caroline, Cecil, Kent, Queen Anne's, Talbot	8 hr
Apr 28, 12:27 AM EDT	Mesoscale Discussion	SPC	Allegany, Frederick, Howard, Montgomery, Washington	63 min
Apr 28, 4:05 AM EDT	Severe Thunderstorm Watch	SPC	Caroline, Cecil, Kent, Queen Anne's, Talbot	6 hr
Apr 28, 7:38 AM EDT	Tornado Watch	SPC	Anne Arundel, Baltimore, Calvert, Carroll, Charles, Dorchester and 10 more	7 hr
Apr 28, 9:45 AM EDT	Severe Thunderstorm Watch	SPC	Caroline, Cecil, Kent, Queen Anne's, Talbot	6 hr
Apr 28, 10:44 AM EDT	Mesoscale Discussion	SPC	Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more	61 min
Apr 28, 11:49 AM EDT	Mesoscale Discussion	SPC	Cecil, Kent, Queen Anne's	56 min
Apr 28, 2:00 PM EDT	Mesoscale Discussion	SPC	Anne Arundel, Calvert, Caroline, Charles, Dorchester, Kent and 7 more	60 min
Apr 28, 2:41 PM EDT	Tornado Watch	SPC	Dorchester, Somerset, Wicomico, Worcester	6 hr
Apr 28, 6:33 PM EDT	Mesoscale Discussion	SPC	Dorchester, Saint Mary's, Somerset, Wicomico, Worcester	57 min
Apr 27, 10:12 PM EDT	Mesoscale Discussion	SPC	Alleghany, Ashe, Forsyth, Rockingham, Stokes, Surry and 3 more	63 min
Apr 28, 12:09 AM EDT	Mesoscale Discussion	SPC	Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 25 more	36 min
Apr 28, 12:56 AM EDT	Tornado Watch	SPC	Alexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 21 more	4 hr
Apr 28, 3:30 AM EDT	Mesoscale Discussion	SPC	Alexander, Anson, Burke, Cabarrus, Catawba, Cleveland and 10 more	90 min
Apr 28, 4:30 AM EDT	Tornado Watch	SPC	Alamance, Anson, Bladen, Chatham, Cumberland, Davidson and 27 more	10 hr
Apr 28, 8:05 AM EDT	Mesoscale Discussion	SPC	Anson, Chatham, Cumberland, Durham, Edgecombe, Franklin and 15 more	85 min
Apr 28, 8:48 AM EDT	Tornado Watch	SPC	Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 15 more	7 hr
Apr 28, 11:22 AM EDT	Mesoscale Discussion	SPC	Beaufort, Bertie, Bladen, Brunswick, Chowan, Columbus and 29 more	53 min
Apr 28, 3:19 PM EDT	Tornado Watch	SPC	Bladen, Brunswick, Columbus, New Hanover, Pender	4 hr
Apr 27, 9:22 PM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Smyth and 5 more	53 min
Apr 28, 12:34 AM EDT	Mesoscale Discussion	SPC	Buchanan, Dickenson, Lee, Russell, Scott, Tazewell and 3 more	26 min

Nearby

Tornado Watches in Virginia, 2011 Tornado Watches in North Carolina, 2011 Tornado Watches in Maryland, 2011 Every tornado 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.