EF1 tornado, Forest Center, Minnesota, July 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

July 6, 2017

Touchdown

2:48 PM CDT (19:48 UTC)

Lifted

2:52 PM CDT (19:52 UTC)

On the ground

4 minutes

Path length

0.9 miles (1.5 km)

Path width

264 yards (241 m)

Deaths

0

Injuries

0

County

Lake County

Touchdown point

48.188, -91.056

Lift-off point

48.178, -91.042

Record number

1707061348-01

A quasi-supercell thunderstorm that developed in Ontario produced a long-tracked tornado that tracked from near McEwen Lake in the wilderness of Quetico Provincial Park for about 7.6 miles and another 0.9 miles into the Boundary Waters Canoe Wilderness Area of northern Minnesota before dissipating. Not only is there satellite evidence of the tornado's path through the wilderness, but Environment Canada conducted a storm survey of the damage. The Canadians rated the damage as high as EF-2 in Canada, and the damage on the short segment into Minnesota as EF-1. The tornado lasted about 17 minutes from its beginning to Canada to its end in Minnesota.

Environment Canada conducted a survey of the long-tracked tornado, which began and mostly occurred in Ontario before crossing into Minnesota, and rated the damage on their end as EF-2, and as EF-1 on the short distance in Minnesota before it dissipated. Satellite imagery is available to show the clear path of the tornado. The total path length was about 8.5 miles, only 0.9 miles of which occurred in Minnesota.

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.

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 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.

Grand Marais/Coo (CKC), 63 km from the path, in the two hours either side.

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

The Duluth radar (KDLH), 173 km away, was scanning. The volume nearest the touchdown began at 19:47 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 MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

1 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.