EF0 tornado, Davidson to Shirley, Minnesota, August 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

August 9, 2021

Touchdown

11:05 PM CDT (04:05 UTC)

Lifted

11:09 PM CDT (04:09 UTC)

On the ground

4 minutes

Path length

2.2 miles (3.6 km)

Path width

150 yards (137 m)

Deaths

0

Injuries

0

Property damage

$5,000

Crop damage

$1,000

County

Polk County

Touchdown point

47.890, -96.730

Lift-off point

47.900, -96.684

Record number

2108092205-01

Severe thunderstorms formed during the late afternoon and early evening in eastern North Dakota, moving into west-central and northwest Minnesota during the mid to late evening. Damaging wind gusts, large hail, and tornadoes were all reported through the course of the event.

This tornado blew out two walls and the roof of a pole shed, broke several ash and cottonwood trees, and peeled up steel siding and roofing on other farm buildings in one farmstead. It carried and/or spread debris to the east and southeast for up to 500 yards while it tracked to the east. It also tore off some roof trim, shingles, and siding at three other farmsteads along its path.

This tornado snapped the tops off of several ash and cottonwood trees at two farmsteads along its path, and cracked a wooden power pole near its base.

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

0 minutes of warning. NWS FGF issued a tornado warning for this county at 04:05 UTC, 0 minutes before the tornado touched down, in force until 04:30 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. The outlook in force was issued at 01:00 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.

Crookston Municipal (CKN), 9 km from the path, in the two hours either side.

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

The Fargo/Grand Forks radar (KMVX), 62 km away, was scanning. The volume nearest the touchdown began at 04:07 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

19 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.