EF1 tornado, Fergus Falls to Dalton, Minnesota, April 21, 2012

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

April 21, 2012

Touchdown

2:11 PM CDT (19:11 UTC)

Lifted

2:19 PM CDT (19:19 UTC)

On the ground

8 minutes

Path length

2.1 miles (3.4 km)

Path width

50 yards (46 m)

Deaths

0

Injuries

0

Property damage

$100,000

County

Otter Tail County

Touchdown point

46.179, -96.070

Lift-off point

46.179, -96.025

Record number

1204211311-01

A series of tornado touchdowns were reported on the afternoon of the 21st, causing minor damage to several farms in west central Minnesota. These tornadoes were associated with a cold core 500 millibar low pressure system passing through the Northern Plains. The surface pattern was also conducive to these events, with a low pressure area also over west central Minnesota in the afternoon. A cold front extended southward from the surface low with a warm front extending out to the east.

This tornado touched down near a farmstead and tracked eastward for about two miles before lifting. The tornado popped three empty steel grain bins off their concrete pads and tumbled them around quite violently. The tornado also tore the doors off an enclosed pole shed, tore the roofing panels off, and uplifted and displaced the rafters. Two young men working at the farmstead witnessed the tornado approaching and sought shelter in the damaged pole shed but were not injured. Peak winds were estimated at 90 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.

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 General Thunderstorms Risk. The outlook in force was issued at 16:17 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), 179 km away, was scanning. The volume nearest the touchdown began at 19:09 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 2012 tornado in MinnesotaEvery tornado in Minnesota since 1950Warnings in force in Minnesota nowThe forecast where you are

10 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.