EF1 tornado, Preston to Rushford, Minnesota, December 15, 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 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

December 15, 2021

Touchdown

8:01 PM CST (02:01 UTC)

Lifted

8:02 PM CST (02:02 UTC)

On the ground

1 minutes

Path length

1.2 miles (1.9 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$40,000

County

Fillmore County

Touchdown point

43.818, -91.903

Lift-off point

43.835, -91.895

Record number

2112152001-01

67 damage points were recorded along this path by NWS ARX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 107 mph.

• Track on both sides of the road. Wind damage to the east,
• Might be on the inflow side but it’s close
• Again, might be on inflow side
• Some softwood tree limbs down as well. Broad.

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

An intense storm system moved across the Upper Midwest on December 15th and produced a rare severe weather outbreak across southeast Minnesota. One person was killed near Rochester (Olmsted County) when a large tree fell on the victim. Twelve tornadoes occurred across parts of Mower, Fillmore, Houston, Dodge, Winona and Wabasha Counties. Eight of these tornadoes were rated EF1 with the others rated EF0. The tornadoes largely moved through rural areas damaging trees, power lines and farm buildings with the exception of an EF0 tornado that moved through the eastern sections of Preston (Fillmore County) and and EF1 tornado that tracked across Homer (Winona County). In addition to the tornadoes, damaging winds occurred with several reports of wind speeds over 70 mph. The highest recorded wind gusts were 85 mph in Plainview (Wabasha County), 84 mph in Harmony (Fillmore County) and Mabel (Fillmore County) and 83 mph south of Grand Meadow (Mower County). A state of emergency was declared in Fillmore County. The Governor of Minnesota authorized emergency assistance for the following counties: Dodge, Fillmore, Houston, Mower, Olmsted and Wabasha.

This was the second tornado of the night in Fillmore County. This narrow EF0 tornado moved across the eastern and northern parts of Preston. Houses, sheds, cars and trees were damaged along the path. The roofs of the fire department and city hall were both damaged.

This was the third tornado of the night in Fillmore County. This EF1 tornado developed northeast of Preston and moved northeast for about 2 miles before dissipating. Farm outbuildings and trees were damaged along the path.

This was the fourth tornado of the night in Fillmore County. This EF1 tornado formed just south of the tiny town of Arendahl and was only on the ground for one minute as it moved rapidly northeast. The damage was limited to a large grove of trees northeast of Arendahl.

This was the fifth tornado of the night in Fillmore County. This EF1 tornado formed south of Rushford and moved to the northeast before dissipating. The tornado destroyed some farm outbuildings and damaged trees along its path.

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

23 minutes of warning. NWS ARX issued a tornado warning for this county at 01:38 UTC, 23 minutes before the tornado touched down, in force until 02:15 UTC.

The county was under a tornado watch, issued at 23:30 UTC and running to 03:17 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 Moderate Risk, with a 0.10 chance of a tornado within 25 miles, in the hatched area where significant tornadoes were expected. The outlook in force was issued at 00:54 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 La Crosse radar (KARX), 57 km away, was scanning. The volume nearest the touchdown began at 02:03 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

124 more were confirmed in the United States that day.

All 125 of them

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.