Alert archive / Virginia / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 49

March 10, 201137 counties in North Carolina; 89 counties in Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Mar 10, 2011, 1:25 PM EST for 37 counties in North Carolina; 89 counties in Virginia. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Mar 10, 2011, 1:25 PM EST (18:25 UTC)
Expired
Mar 10, 2011, 7:56 PM EST
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 126 counties

Alamance County, NC, Bertie County, NC, Caswell County, NC, Chatham County, NC, Cumberland County, NC, Duplin County, NC, Durham County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Granville County, NC, Greene County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hertford County, NC, Hoke County, NC, Johnston County, NC, Lee County, NC, Lenoir County, NC, Martin County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Pitt County, NC, Randolph County, NC, Richmond County, NC, Rockingham County, NC, Sampson County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wayne County, NC, Wilson County, NC, 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, Botetourt 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 Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Covington, 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 Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Petersburg, VA, City of Richmond, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Suffolk, VA, City of Waynesboro, 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, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Highland County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, New Kent County, VA, Nottoway County, VA, Orange County, VA, Page 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, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA

The radar

The Roanoke radar (KFCX), 123 km from the middle of the area, began a volume at 18:25 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
60%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Mar 10, 2:35 PM ESTFlash Flood WarningLWXAlbemarle, Augusta, Nelson, City of Charlottesville, City of Staunton, City of Waynesboro4 hr
Mar 10, 3:05 PM ESTFlash Flood WarningRNKAmherst, Botetourt, Rockbridge, City of Buena Vista, City of Lexington5 hr
Mar 10, 3:38 PM ESTSevere Thunderstorm WarningRNKCharlotte, Halifax41 min
Mar 10, 3:47 PM ESTSevere Thunderstorm WarningAKQLunenburg, Mecklenburg, Prince Edward58 min
Mar 10, 4:10 PM ESTSevere Thunderstorm WarningAKQCumberland, Prince Edward50 min
Mar 10, 4:16 PM ESTSevere Thunderstorm WarningRNKAppomattox, Buckingham46 min
Mar 10, 4:36 PM ESTFlash Flood WarningLWXAlbemarle, Culpeper, Fauquier, Greene, King George, Madison and 5 more3 hr
Mar 10, 4:38 PM ESTSevere Thunderstorm WarningAKQNorthampton52 min
Mar 10, 4:50 PM ESTSevere Thunderstorm WarningRAHEdgecombe, Nash, Wayne, Wilson55 min
Mar 10, 5:02 PM ESTSevere Thunderstorm WarningLWXCulpeper, Fauquier, Madison, Page, Rappahannock, Warren58 min
Mar 10, 5:15 PM ESTSevere Thunderstorm WarningAKQCaroline, Goochland, Hanover, Louisa, Powhatan60 min
Mar 10, 5:18 PM ESTSevere Thunderstorm WarningLWXCulpeper, Fauquier, Madison, Orange, Spotsylvania, Stafford and 1 more57 min
Mar 10, 5:26 PM ESTSevere Thunderstorm WarningRAHEdgecombe, Halifax, Nash42 min
Mar 10, 5:28 PM ESTSevere Thunderstorm WarningAKQCharles City, Chesterfield, Dinwiddie, Hanover, Henrico, New Kent and 6 more47 min
Mar 10, 5:34 PM ESTSevere Thunderstorm WarningLWXClarke, Fauquier, Frederick, Loudoun, Warren, City of Winchester41 min
Mar 10, 5:48 PM ESTFlash Flood WarningLWXArlington, Fairfax, Fauquier, King George, Loudoun, Prince William and 6 more4 hr
Mar 10, 6:07 PM ESTFlash Flood WarningLWXLoudoun3 hr
Mar 10, 6:10 PM ESTSevere Thunderstorm WarningAKQCharles City, Essex, Gloucester, Hanover, Henrico, James City and 7 more50 min
Mar 10, 6:10 PM ESTSevere Thunderstorm WarningLWXCulpeper, Fairfax, Fauquier, King George, Loudoun, Orange and 7 more65 min
Mar 10, 6:14 PM ESTTornado WarningLWXFauquier, Prince William31 min
Mar 10, 6:20 PM ESTSevere Thunderstorm WarningAKQCaroline, Essex, King and Queen, King William, Richmond, Westmoreland40 min
Mar 10, 6:53 PM ESTSevere Thunderstorm WarningAKQEssex, Gloucester, King and Queen, Lancaster, Mathews, Middlesex and 4 more52 min
Mar 10, 6:58 PM ESTTornado WarningLWXFairfax, Loudoun, Prince William, City of Manassas, City of Manassas Park32 min
Mar 10, 7:06 PM ESTSevere Thunderstorm WarningLWXFairfax54 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, 6.4 hours before the alert went out and 55 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, Roanoke, VA at 12:00Z on 2011-03-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 8 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Roanoke, VA at 12:00Z on 2011-03-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 170 square meters per square second.1939587897117Sfc1 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
8 J/kg
Mixed-layer CIN
-47 J/kg
Mixed-layer LCL
486 m above ground
0-6 km bulk shear
77 kt
0-1 km storm-relative helicity
170 m²/s²
0-3 km storm-relative helicity
217 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.

461 
WWUS20 KWNS 101825
SEL9  
SPC WW 101825
NCZ000-VAZ000-110100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 49
NWS STORM PREDICTION CENTER NORMAN OK
125 PM EST THU MAR 10 2011

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

       LARGE PART OF CENTRAL AND EASTERN NORTH CAROLINA
       A LARGE PART OF CENTRAL AND SOUTHERN VIRGINIA

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 125 PM UNTIL
800 PM EST.

HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES NORTH OF
CHARLOTTESVILLE VIRGINIA TO 10 MILES SOUTH SOUTHWEST OF
FAYETTEVILLE NORTH CAROLINA.  FOR A COMPLETE DEPICTION OF THE
WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...AS STRONG UPPER TROUGH APPROACHES AREA FROM THE
SW...AIR MASS HAS BECOME SUFFICIENTLY UNSTABLE TO SUPPORT
THUNDERSTORMS.  WITH 50-60KT BRN SHEAR...THUNDERSTORMS WILL DEVELOP
INTO SHORT LINE SEGMENTS/BOWS AS THEY MOVE RAPIDLY NEWD.  PRIMARY
THREAT WILL BE DAMAGING WINDS...HOWEVER A BRIEF TORNADO OR TWO IS
POSSIBLE GIVEN THE STRONG LOW LEVEL SHEAR.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS.
A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM MOTION
VECTOR 22035.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Mar 10, 12:51 PM ESTMesoscale DiscussionSPCAlamance, Bladen, Caswell, Chatham, Columbus, Cumberland and 22 more114 min
Mar 10, 4:26 PM ESTMesoscale DiscussionSPCNorthampton94 min

Nearby

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