EF0 tornado, Collis to Dumont, Minnesota, October 9, 2021

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

October 9, 2021

Touchdown

7:21 PM CDT (00:21 UTC)

Lifted

7:23 PM CDT (00:23 UTC)

On the ground

2 minutes

Path length

1.6 miles (2.6 km)

Path width

10 yards (9 m)

Deaths

0

Injuries

0

County

Traverse County

Touchdown point

45.760, -96.290

Lift-off point

45.770, -96.260

Record number

2110091821-01

3 damage points were recorded along this path by NWS ABR, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 104 mph.

• Tree uprooted, large tree branches down, sheet metal tossed around farmyard
• Damage to roof and walls of pole barn, large tree branches broken

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

During the evening hours, a line of storms along a boundary moved across west central Minnesota, producing 70 mph winds, locally heavy rainfall, and two tornadoes. The tornadoes did minor damage to three farmsteads.

A tornado was on the groud for just shy of one mile causing minor damage to two farmsteads. The first farm had an uprooted tree, tree branches down and sheet metal tossed around the farmyard. The second farm, which was located about one half mile to the northeast, reported damage to roof and walls of a pole barn and large tree branches broken.

Tornado damage was first observed to the northeast of the intersection of 620th St and 760th Ave, where a single cottonwood tree in a line of trees was snapped at the base. About a mile to the northeast on 770th Ave, another cottonwood tree had a large branch broken and sporadically scattered leaves and twigs. The tornado then damaged a farmstead where an empty grain bin was removed from the base and lofted, rolled roughly 0.4 miles. Additional metal debris was also noted along the northeast path.

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 19:56 UTC and running to 01:52 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 0.05 chance of a tornado within 25 miles. The outlook in force was issued at 19:52 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.

Wheaton Ndb (ETH), 21 km from the path, in the two hours either side.

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

The Aberdeen radar (KABR), 170 km away, was scanning. The volume nearest the touchdown began at 00:17 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 2021 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

6 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.