EF2 tornado, Hovland, Minnesota, October 10, 2021

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 mphthis tornado

   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

EF2

Date

October 10, 2021

Touchdown

6:10 PM CDT (23:10 UTC)

Lifted

6:20 PM CDT (23:20 UTC)

On the ground

10 minutes

Path length

4.0 miles (6.4 km)

Path width

500 yards (457 m)

Deaths

0

Injuries

0

County

Cook County

Touchdown point

48.044, -90.296

Lift-off point

48.099, -90.296

Record number

2110101710-01

4 damage points were recorded along this path by NWS DLH, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF2. The highest wind the damage implies is 115 mph.

• Damage path becomes widest north of Clearwater Lake with a clear convergent pattern of treefall. Photo courtesy USFS/Superior National Forest.
• Swath of approximately 250m (270 yards) across of downed trees just north of Rocky Lake.
• Video from hiker shows impassable Border Route Trail with significant, widespread treefall. Many trees snapped near the base.

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

An area of low pressure working across the Upper Midwest on the 10th was able to pull abnormally high moisture into the region leading to sufficient instability for the development of storms. An upper jet was also over the area contributing to higher than normal amounts of shear as well resulting in some of the storms becoming severe across the region. Isolated reports of large hail and damaging winds were received along the North Shore of Lake Superior along with a rare October tornado that developed over the Boundary Waters Canoe Area Wilderness and tracked northward into Canada.

A rare late-season strong tornado caused tree damage|across parts of the Boundary Waters Canoe Area Wilderness in |northern Cook County. The tornado appeared to begin on Alder Lake, |initially causing damage near Campsite #3 where a small swath of |trees were downed, several snapped halfway down their trunks. The |tornado then traveled north causing sporadic damage until just north |of Rocky Lake where there was a more concentrated area of downed |trees roughly 270 yards across. Sporadic tree damage continued until |reaching Clearwater Lake and crossing the lake just west of Campsite |#5, causing significant damage north of Clearwater Lake and north to |the International Border (Mountain Lake). Significant tree damage was|observed along the Border Route Trail, of which passage was made |impossible as the tornado reached its maximum width of around 500 |yards as it moved across the trail. Numerous trees were snapped near |their bases within this area of damage. The coverage of damage was |widespread with satellite imagery depicting over 80% of trees |uprooted, bent, or snapped across its path near the Border Route |Trail. The tornado then crossed the International Border and continued into Northwestern Ontario, Canada. No private property was damaged along the course of the tornado. ||The National Weather Service appreciates the public reports, photos,|and videos of this tornado damage, aerial photographs from the US |Forest Service, and satellite imagery shared by the Northern |Tornadoes Project (Western University in Canada) which all aided in |an accurate assessment of the damage.

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

34 minutes of warning. NWS DLH issued a tornado warning for this county at 22:36 UTC, 34 minutes before the tornado touched down, in force until 23:15 UTC.

The county was under a severe thunderstorm watch, issued at 18:42 UTC and running to 01:25 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 19:50 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 Duluth radar (KDLH), 199 km away, was scanning. The volume nearest the touchdown began at 23:11 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

18 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.