Unrated tornado, Micawber to Mason, Oklahoma, May 27, 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 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. Unratedthis tornado

   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

Unrated

Date

May 27, 2017

Touchdown

8:55 PM CDT (01:55 UTC)

Lifted

9:02 PM CDT (02:02 UTC)

On the ground

7 minutes

Path length

0.6 miles (1.0 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Okfuskee County

Touchdown point

35.566, -96.424

Lift-off point

35.561, -96.415

Record number

1705271955-01

Strong to severe thunderstorms developed during the late afternoon hours of the 27th along and ahead of a cold front that was moving into eastern Oklahoma. Very unstable air over the area, combined with strong deep-layer wind shear, resulted in widespread severe weather to develop. Several tornadoes, hail up to softball size, and damaging wind gusts occurred with the strongest storms.

Storm chasers observed a tornado over open country for about six minutes. An NWS ground survey team was unable to find any damage from the tornado, mainly due to the fact the tornado was over terrain that was inaccessible by roads. Storm chaser photos and video did show some debris occasionally in the tornadic circulation, most likely from trees.

Storm chasers observed a tornado over open country. An NWS storm survey team found no damage associated with the tornado, mainly due to the fact it remained over terrain that was inaccessible by road. An unmanned aircraft system (UAS) piloted by researchers from the Oklahoma State University flew the suspected area where the tornado occurred but data obtained were inconclusive.

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

29 minutes of warning. NWS TSA issued a tornado warning for this county at 01:26 UTC, 29 minutes before the tornado touched down, in force until 02:15 UTC.

The county was under a tornado watch, issued at 21:05 UTC and running to 05:00 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 Enhanced Risk, with a 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 00:44 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 Norman radar (KTLX), 82 km away, was scanning. The volume nearest the touchdown began at 01:56 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

13 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.