EF1 tornado, Bunch to Lyons, Oklahoma, March 6, 2017

1. EF065 to 85 mph

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

2. EF186 to 110 mphthis tornado

   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

EF1

Date

March 6, 2017

Touchdown

9:44 PM CST (03:44 UTC)

Lifted

9:55 PM CST (03:55 UTC)

On the ground

11 minutes

Path length

6.1 miles (9.8 km)

Path width

650 yards (594 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Adair County

Touchdown point

35.656, -94.704

Lift-off point

35.723, -94.635

Record number

1703062144-01

25 damage points were recorded along this path by NWS TSA, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

• metal roofing material blown nnw

Survey points are preliminary and are the raw material the published rating was built from. Source: NWS Damage Assessment Toolkit.

Strong to severe thunderstorms developed during the evening hours of the 6th over north central Oklahoma, along a cold front that moved into the area. A very moist and moderately unstable air mass was in place over eastern Oklahoma ahead of these storms. The line of thunderstorms moved east across eastern Oklahoma during the evening hours of the 6th and early morning hours of the 7th, producing hail up to half dollar size and damaging wind. Other strong to severe thunderstorms developed well ahead of the cold front across east central Oklahoma. Strong wind shear that was present in the atmosphere over the area allowed some of these storms to develop into supercell thunderstorms, which produced a tornado in Adair County and hail up to golfball size.

This tornado destroyed several outbuildings, damaged several homes, uprooted numerous trees, and blew down power poles. Based on this damage, estimated maximum wind in the tornado was 90 to 100 mph.

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

4 minutes of warning. NWS TSA issued a tornado warning for this county at 03:40 UTC, 4 minutes before the tornado touched down, in force until 04:15 UTC.

The county was under a tornado watch, issued at 00:51 UTC and running to 06:54 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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 00:54 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 Western Arkansas radar (KSRX), 52 km away, was scanning. The volume nearest the touchdown began at 03:43 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 OklahomaEvery tornado in Oklahoma since 1950Warnings in force in Oklahoma nowThe forecast where you are

53 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.