EF0 tornado, South Washington, Virginia, April 6, 2017

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

April 6, 2017

Touchdown

12:39 PM CDT (17:39 UTC)

Lifted

12:45 PM CDT (17:45 UTC)

On the ground

6 minutes

Path length

4.9 miles (7.9 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Counties

Arlington County

Touchdown point

38.850, -77.070

Lift-off point

38.900, -77.010

Record number

1704061139-01

Cutoff low pressure was over the Ohio Valley. Another area of low pressure strengthened overhead on the occluded boundary. Warm and moist air from the south lead to an unstable atmosphere. Strong shear profiles were in place due to the cutoff low to the west. Strong lift associated with the developing low combined with strong shear and enough instability to produce severe thunderstorms and isolated tornadoes.

Trees were snapped along Interstate 395 adjacent to Army-Navy |Country Club at approximately 1:39 PM EDT. Video of a portion of |the Pentagon Parking Lot showed a vortex cross between two light |poles, ripping off one lamp from the top of the poles. Additional |video from the Pentagon showed two rope-like funnel clouds form at|the same time, although it could not be determined from the video|whether these funnels touched the ground or were attached to the |cloud base. Video from the National Park Service National Mall and|Memorial Parks showed a waterspout over the Potomac River west of |the Tidal Basin; however, it is not clear the vertical extent of |this waterspout and whether it was sourced from the cloud base, or|an independent vortex associated with the gust front.

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

No tornado warning for this county appears in the archive as in force at the moment the tornado touched down.

The county was under a severe thunderstorm watch, issued at 16:45 UTC and running to 18:21 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 Marginal Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 16:12 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.

Washington/National (DCA), 3 km from the path, in the two hours either side.

From the Iowa Environmental Mesonet's archive of airport observations.

The Sterling radar (KLWX), 40 km away, was scanning. The volume nearest the touchdown began at 17:37 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 2017 tornado in VirginiaEvery tornado in Virginia since 1950Warnings in force in Virginia nowThe forecast where you are

11 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.