Alert archive / Virginia / Tornado Watches in 2011

Tornado Watch 101

April 5, 20114 states

The Storm Prediction Center issued this tornado watch at Apr 5, 2011, 2:18 AM EDT for 4 states. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued
Apr 5, 2011, 2:18 AM EDT (06:18 UTC)
Expired
Apr 5, 2011, 10:00 AM EDT
In force
8 hr
Issued by
the Storm Prediction Center
Largest hail expected
0.5 in
Strongest gust expected
60 kt
All 123 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Worcester County, MD, Bertie County, NC, Camden County, NC, Caswell County, NC, Chowan County, NC, Currituck County, NC, Gates County, NC, Hertford County, NC, Northampton County, NC, Pasquotank County, NC, Perquimans County, NC, Rockingham County, NC, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Bedford County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, 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 Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Franklin County, VA, Gloucester County, VA, Goochland County, VA, Greene 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 George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 93 km from the middle of the area, began a volume at 06:18 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
60%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
5%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 5, 2:26 AM EDTSevere Thunderstorm WarningRNKAmherst, Appomattox, Bedford, Buckingham, Campbell, Charlotte and 4 more57 min
Apr 5, 2:36 AM EDTSevere Thunderstorm WarningRNKCampbell, Charlotte, Halifax, Pittsylvania54 min
Apr 5, 2:56 AM EDTSevere Thunderstorm WarningAKQCumberland, Lunenburg, Prince Edward64 min
Apr 5, 2:58 AM EDTSevere Thunderstorm WarningRNKCaswell, Rockingham62 min
Apr 5, 3:04 AM EDTSevere Thunderstorm WarningLWXAlbemarle, Clarke, Culpeper, Fauquier, Greene, Loudoun and 7 more56 min
Apr 5, 3:12 AM EDTTornado WarningRNKCaswell14 min
Apr 5, 3:19 AM EDTSevere Thunderstorm WarningAKQCumberland, Fluvanna, Goochland, Louisa41 min
Apr 5, 3:44 AM EDTSevere Thunderstorm WarningAKQAmelia, Brunswick, Dinwiddie, Lunenburg, Mecklenburg, Nottoway61 min
Apr 5, 3:54 AM EDTSevere Thunderstorm WarningAKQCaroline, Goochland, Hanover, Louisa, Powhatan51 min
Apr 5, 4:05 AM EDTSevere Thunderstorm WarningLWXKing George, Spotsylvania, Stafford40 min
Apr 5, 4:29 AM EDTSevere Thunderstorm WarningLWXAnne Arundel, Calvert, Charles, Montgomery, Prince George's51 min
Apr 5, 4:36 AM EDTSevere Thunderstorm WarningAKQAmelia, Charles City, Chesterfield, Dinwiddie, Hanover, Henrico and 7 more54 min
Apr 5, 4:38 AM EDTSevere Thunderstorm WarningLWXCalvert, Charles, Saint Mary's67 min
Apr 5, 4:40 AM EDTSevere Thunderstorm WarningLWXAnne Arundel, Baltimore, Carroll, Harford, Howard, Montgomery and 2 more53 min
Apr 5, 4:46 AM EDTTornado WarningLWXAnne Arundel, Calvert, Charles, Prince George's, Saint Mary's29 min
Apr 5, 4:55 AM EDTTornado WarningLWXAnne Arundel, Prince George's24 min
Apr 5, 4:56 AM EDTSevere Thunderstorm WarningAKQEssex, King and Queen, King William, Lancaster, Middlesex, Northumberland and 2 more64 min
Apr 5, 4:57 AM EDTTornado WarningLWXCalvert, Charles, Prince George's, Saint Mary's33 min
Apr 5, 4:58 AM EDTTornado WarningAKQCharles City, Henrico, King and Queen, King William, New Kent32 min
Apr 5, 5:01 AM EDTSevere Thunderstorm WarningPHIKent, New Castle74 min
Apr 5, 5:05 AM EDTTornado WarningLWXAnne Arundel, Calvert, Charles, Prince George's14 min
Apr 5, 5:22 AM EDTTornado WarningLWXCalvert, Saint Mary's23 min
Apr 5, 5:23 AM EDTSevere Thunderstorm WarningAKQCharles City, Isle of Wight, James City, Prince George, Southampton, Surry and 4 more37 min
Apr 5, 5:28 AM EDTSevere Thunderstorm WarningPHIKent, New Castle, Sussex62 min
Apr 5, 5:28 AM EDTSevere Thunderstorm WarningAKQCharles City, Gloucester, James City, King and Queen, Lancaster, Mathews and 4 more51 min
Apr 5, 5:42 AM EDTSevere Thunderstorm WarningAKQGloucester, Isle of Wight, James City, Northampton, York, City of Hampton and 4 more63 min
Apr 5, 5:43 AM EDTSevere Thunderstorm WarningAKQDorchester, Somerset, Wicomico, Worcester62 min
Apr 5, 6:07 AM EDTSevere Thunderstorm WarningAKQCity of Chesapeake, City of Norfolk, City of Portsmouth, City of Virginia Beach53 min
Apr 5, 6:10 AM EDTSevere Thunderstorm WarningAKQBertie, Camden, Chowan, Currituck, Gates, Hertford and 2 more65 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

Washington/Dulle, VA (KIAD), launched 00:00Z, 6.3 hours before the alert went out and 137 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-pSkew-T log-p diagram, Washington/Dulle, VA at 00:00Z on 2011-04-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2011-04-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 284 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
4112 m above ground
0-6 km bulk shear
49 kt
0-1 km storm-relative helicity
284 m²/s²
0-3 km storm-relative helicity
328 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.

217 
WWUS20 KWNS 050619
SEL1
SPC WW 050619
DCZ000-DEZ000-MDZ000-NCZ000-VAZ000-CWZ000-051400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 101
NWS STORM PREDICTION CENTER NORMAN OK
220 AM EDT TUE APR 5 2011

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

       DISTRICT OF COLUMBIA
       DELAWARE
       EASTERN MARYLAND
       NORTHERN NORTH CAROLINA
       VIRGINIA
       COASTAL WATERS

EFFECTIVE THIS TUESDAY MORNING FROM 220 AM UNTIL 1000 AM EDT.

TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 85 STATUTE
MILES EAST AND WEST OF A LINE FROM ROANOKE RAPIDS NORTH CAROLINA
TO 35 MILES NORTH NORTHEAST OF BALTIMORE MARYLAND.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU1).

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...THIS TORNADO WATCH REPLACES SEVERE
THUNDERSTORM WATCH NUMBER 99. WATCH NUMBER 99 WILL NOT BE IN
EFFECT AFTER 220 AM EDT. CONTINUE...WW 97...WW 98...WW 100...

DISCUSSION...BROKEN BAND OF TSTMS EMERGING FROM THE BLUE RIDGE WILL
CONTINUE TO EXHIBIT SUPERCELL AND LEWP CHARACTERISTICS AS IT RACES
NEWD ACROSS THE WW AREA EARLY THIS MORNING.  IN ADDITION TO THE
THREAT FOR DAMAGING WINDS...TORNADO POTENTIAL WILL BE ENHANCED BY
AMBIENT STRONG LOW-LEVEL SHEAR AND INTERACTION OF CONVECTIVE BAND
WITH OUTFLOW BOUNDARY RETREATING NWD THROUGH THE REGION.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
350. MEAN STORM MOTION VECTOR 25050.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 5, 2:13 AM EDTMesoscale DiscussionSPCKent, Sussex32 min
Apr 5, 3:34 AM EDTMesoscale DiscussionSPCKent, New Castle, Sussex116 min
Apr 5, 5:07 AM EDTSevere Thunderstorm WatchSPCCecil2 hr
Apr 5, 5:03 AM EDTMesoscale DiscussionSPCAtlantic, Burlington, Camden, Cape May, Cumberland, Gloucester and 8 more27 min
Apr 5, 6:25 AM EDTMesoscale DiscussionSPCAtlantic, Bergen, Burlington, Camden, Cape May, Cumberland and 14 more2 hr
Apr 4, 9:32 PM EDTMesoscale DiscussionSPCAlexander, Buncombe, Burke, Catawba, Cleveland, Gaston and 8 more58 min
Apr 4, 9:45 PM EDTSevere Thunderstorm WatchSPCAlexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 22 more5 hr
Apr 5, 12:21 AM EDTMesoscale DiscussionSPCAlamance, Anson, Chatham, Cumberland, Harnett, Hoke and 7 more84 min
Apr 5, 12:36 AM EDTSevere Thunderstorm WatchSPCAlleghany, Caswell, Rockingham, Stokes, Surry, Wilkes and 1 more111 min
Apr 5, 12:48 AM EDTTornado WatchSPCAlamance, Anson, Bladen, Chatham, Cumberland, Davidson and 27 more5 hr
Apr 5, 2:24 AM EDTMesoscale DiscussionSPCCabarrus, Mecklenburg, Rowan66 min
Apr 5, 4:00 AM EDTTornado WatchSPCBeaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 15 more6 hr
Apr 5, 7:08 AM EDTMesoscale DiscussionSPCBeaufort, Brunswick, Carteret, Craven, Currituck, Dare and 10 more2 hr
Apr 5, 10:15 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 26 more90 min

Nearby

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