EF0 tornado, Crawford, Minnesota, July 21, 2017

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

July 21, 2017

Touchdown

5:34 PM CDT (22:34 UTC)

Lifted

5:35 PM CDT (22:35 UTC)

On the ground

1 minutes

Path length

0.4 miles (0.6 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Clay County

Touchdown point

46.810, -96.580

Lift-off point

46.810, -96.580

Record number

1707211634-01

On the morning of July 21st, a thunderstorm just north of the Canadian border moved southeast into Cavalier County, North Dakota, where it dropped large hail. This storm weakened for a few hours, but remained intact. The same storm re-intensified by mid afternoon over eastern Marshall County, Minnesota, and remained very strong until it reached the town of Saum, in Beltrami County, Minnesota. Meanwhile, temperatures by the afternoon of the 21st rose into the lower 90s, with dew points in the mid 60s to lower 70s. More strong thunderstorms moved into the Cooperstown, North Dakota, area, and tracked to the east-southeast. Then, during the early evening, a line of strong storms consolidated from near Bemidji to just east of Moorhead, Minnesota. This line of storms held together as it moved to the east-southeast. By late evening, more strong storms moved into the Devils Lake region, still tracking to the east-southeast. This area of storms continued to hold together, flaring up near Hunter, North Dakota, and near Pelican Rapids, Minnesota, where it produced several reports of strong winds.

A weak tornado was observed over largely open farmland just north of Interstate 94 in extreme southeast Glyndon Township. Peak winds were estimated at 75 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.

The county was under a severe thunderstorm watch, issued at 20:20 UTC and running to 02:15 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 0.02 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.

The Fargo/Grand Forks radar (KMVX), 98 km away, was scanning. The volume nearest the touchdown began at 22:34 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

5 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.