EF1 tornado, Oologah to Chelsea, Oklahoma, August 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

August 6, 2017

Touchdown

2:11 AM CDT (07:11 UTC)

Lifted

2:13 AM CDT (07:13 UTC)

On the ground

2 minutes

Path length

0.9 miles (1.4 km)

Path width

400 yards (366 m)

Deaths

0

Injuries

0

Property damage

$5,000

Counties

Rogers and Mayes counties

Touchdown point

36.450, -95.441

Lift-off point

36.461, -95.433

Record number

1708060111-01

9 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 98 mph.

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

A surface low pressure system was positioned over southwestern Kansas during the evening of the 5th, with a stationary frontal boundary extending southeast from the low into northeastern Oklahoma and northwestern Arkansas. Thunderstorms developed over northwestern Oklahoma and south central Kansas during the evening hours and moved east into northeastern Oklahoma during the late evening hours of the 5th and early morning hours of the 6th. The thunderstorms evolved into a nearly solid line by the time they reached northeastern Oklahoma and resulted in widespread damaging wind. Very strong low-level wind shear ahead of the line allowed for the development of several areas of rotation along and within the leading edge of the thunderstorms. Several tornadoes formed from these low-level circulations, including a strong tornado that resulted in severe damage across portions of the City of Tulsa.

This tornado developed east of Oologah where barns and trees were damaged. The tornado moved northward along the S 4110 Road where power poles were snapped, a home was damaged, and trees were blown down. The tornado turned more northwesterly after crossing the E 370 Road and dissipated south of the E 350 Road. Based on this damage, maximum estimated wind in the tornado was 90 to 100 mph.

This is the first segment of a two segment tornado. The tornado developed just west of Highway 28 along and just south of the 390 Road to the south of Chelsea. The tornado uprooted trees and damaged the roof of an agricultural building. Based on this damage, maximum estimated wind in this segment of the tornado was 90 to 95 mph. The tornado continued into Mayes County.

This is the second segment of a two segment tornado. The tornado crossed into Mayes County snapping large tree limbs before dissipating. Based on this damage, maximum estimated wind in this segment of the tornado was 70 to 80 mph.

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. One was issued for the county at another hour that day.

The county was under a severe thunderstorm watch, issued at 00:16 UTC and running to 09:00 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 General Thunderstorms Risk. The outlook in force was issued at 05:52 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.

Claremore Regional Airport (GCM), 19 km from the path, in the two hours either side.

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

The Tulsa radar (KINX), 33 km away, was scanning. The volume nearest the touchdown began at 07:08 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

3 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.