EF0 tornado, Bull Run to Pender, Virginia, March 10, 2011

1. EF065 to 85 mphthis tornado

   Light damage. Surface peeled off some roofs, gutters and siding damaged, branches broken, shallow-rooted trees pushed over.

2. EF186 to 110 mph

   Moderate damage. Roofs badly stripped, mobile homes overturned or badly damaged, exterior doors lost, windows broken.

3. EF2111 to 135 mph

   Considerable damage. Roofs torn off well-built houses, frame homes shifted on their foundations, mobile homes destroyed, large trees snapped or uprooted, cars lifted off the ground.

4. EF3136 to 165 mph

   Severe damage. Whole stories of well-built houses destroyed, large buildings badly damaged, trains overturned, trees debarked, heavy cars lifted and thrown.

5. EF4166 to 200 mph

   Devastating damage. Well-built houses leveled, structures with weak foundations moved some distance, cars thrown and large missiles generated.

6. EF5over 200 mph

   Incredible damage. Strong frame houses swept off their foundations, car-sized missiles thrown more than 100 meters, steel-reinforced concrete badly damaged, high-rise buildings deformed.

7. Unrated

   The survey recorded a tornado but could not put a number on it, most often because it crossed open country and damaged nothing a rating can be read from.

Rating

EF0

Date

March 10, 2011

Touchdown

6:59 PM EST (23:59 UTC)

Lifted

7:03 PM EST (00:03 UTC)

On the ground

4 minutes

Path length

4.9 miles (7.9 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$5,000

County

Fairfax County

Touchdown point

38.852, -77.451

Lift-off point

38.899, -77.382

Record number

1103101759-01

A strong cold front slowly passed through the area on the 10th. Plenty of moisture from the Gulf of Mexico and Atlantic Ocean were drawn into the region ahead of the front. A warm and moist southerly flow ahead of the front caused limited instability to develop. Strong lift from the front combined with the instability to trigger showers and thunderstorms. ||Winds just a few thousand feet above the surface were quite strong. Some thunderstorms were able to transport these winds down to the surface during the afternoon and evening hours of the 10th. There was also enough rotation at the lower levels of the atmosphere for isolated tornadoes in the stronger thunderstorms.

Many broken tree branches were located near the Sully Station Shopping Center west of Braddock Road. Pine trees were snapped in Ellanor Lawrance Park along southbound Virginia Route 28. More pine trees were snapped in the woods of Lawrence Park north of Walney House. Minor tree damage continued across US Route 50 near the International Town and Country Club.

From NOAA NCEI's Storm Events Database, the narrative the local forecast office wrote for Storm Data.

1 minute of warning. NWS LWX issued a tornado warning for this county at 23:58 UTC, 1 minute before the tornado touched down, in force until 00:30 UTC.

The county was under a severe thunderstorm watch, issued at 23:25 UTC and running to 00:56 UTC.

Every warning and watch covering the touchdown point that day, from the Iowa Environmental Mesonet's archive of National Weather Service products. Lead time is measured from the issue of the warning in force to the touchdown time in the database, both of which were recorded to the minute by different people.

The Storm Prediction Center had this point in a Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:30 UTC.

SPC's Day 1 convective outlook as it stood when the tornado began, read at the touchdown point. The same archive is on the radar archive.

The radiosonde launches on either side of the tornado, from the nearest station that was launching then, drawn and analyzed the way Storm Lab does: the same diagram, the same parcel and shear definitions SPC's mesoanalysis uses.

The Sterling radar (KLWX), 13 km away, was scanning. The volume nearest the touchdown began at 23:59 UTC.

Open the radar archive at this moment, over the track

Reflectivity and velocity, decoded from the Level II archive in the browser. Volumes take a few seconds to open the first time.

Local storm reports within 60 km of the path, in the three hours either side.

From the Iowa Environmental Mesonet's archive of National Weather Service local storm reports.

The live radar over the trackEvery 2011 tornado in VirginiaEvery tornado in Virginia since 1950Warnings in force in Virginia nowThe forecast where you are

2 more were confirmed in the United States that day.

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. Tornado counts rise through the record as reporting improved, so a year in the 1950s is not comparable with one today except for the strongest tornadoes, which were always noticed.

NOAA Storm Prediction Center tornado database, 1950-2025, the official record kept by NOAA's Storm Prediction Center.