EF1 tornado, Myrtle to Moscow, 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

7:10 PM CST (01:10 UTC)

Lifted

7:15 PM CST (01:15 UTC)

On the ground

5 minutes

Path length

6.3 miles (10.2 km)

Path width

100 yards (91 m)

Deaths

0

Injuries

0

County

Freeborn County

Touchdown point

43.537, -93.198

Lift-off point

43.620, -93.142

Record number

2112151910-02

107 damage points were recorded along this path by NWS ARX and NWS DMX and NWS MPX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 100 mph.

• Silo dented near the top. It was nearly full.
• A large storage shed lost part of its roof and the door was blown in. Several trees were damaged.
• Pivot irrigation system knocked over.
• Grain bin from farm just to the ssw.

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

A low pressure system of historic strength led to a variety of high-end weather impacts from the central plains to the Upper Midwest and Great Lakes December 15-16. An unprecedented December severe weather unfolded over portions of Minnesota and Wisconsin Wednesday evening, with the Storm Prediction Center issuing their farthest-north Moderate Risk for the Month of December. A serial derecho moving at 60-70 mph tracked from Kansas to Wisconsin, resulting in over 400 reports of damaging wind and numerous tornadoes. Most of the damage across our area occurred from south-central Minnesota through west-central Wisconsin. The strongest tornado damage occurred in Hartland.||Before the thunderstorms, strong southerly winds led to record high temperature at many sites across the Upper Midwest. Temperatures warmed into the mid to upper 50s across much of central Minnesota and western Wisconsin, and even exceeded 60 degrees across southern Minnesota. The warm temperatures melted what was left of the snowpack from the December 10 winter storm, which led to widespread dense fog through much of the morning and afternoon.||After the thunderstorms, strong gradient winds and widespread wind gusts in excess of 50 mph developed for several hours late Wednesday night and into the overnight hours. The Redwood Falls airport measured a gust of 78 mph at 11:30 PM.||Temperatures quickly fell below freezing across western and central Minnesota Wednesday night, causing rain to change over to a wintry mix of freezing drizzle and snow. Snowfall accumulations of 1-4 inches, along with the strong gusty winds, led to low visibility and travel hazards late Wednesday night into Thursday morning.

This tornado hit several farms, including one where seven buildings had enough damage so they will be totaled. Several windows of a house were blown out. A machine shed at another farm had several pillars of a large machine shed pulled out of the ground. At the end of the tornado, a home had many shingles removed.

This tornado developed in Worth County Iowa along 500th Street, initially producing some tree damage (see separate entry from NWS Des Moines). As it crossed into Freeborn County Minnesota, it displaced and destroyed an empty silo on State Line Road. It then destroyed a cattle barn and a pole crashed through a car. The tornado then continued to produce mostly minor tree damage and moved northeast into southwestern Mower County (see separate entry from NWS La Crosse).

A brief tornado occurred south of Glenville. It spun up around 782nd Ave and tracked northeast producing some tree damage until it reached 795th Ave. There, it damaged farm buildings and tossed hay bales across the road.

The tornado hit one farmstead, knocking down trees and causing some damage to outbuildings. At the next farmstead, it destroyed a machine shed. A nearly full grain bin was dented at the top. The house had part of its roof taken off. Near the end of its path, two irrigation pivots were blown over. It was uncertain whether the tornado moved into Mower County, and so the path was not extended into Mower County.

This tornado hit several farmsteads, partially removing the roofs of several outbuildings and a turkey barn. It dented a silo. Trees fell on a number of sheds and vehicles.

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

15 minutes of warning. NWS MPX issued a tornado warning for this county at 00:55 UTC, 15 minutes before the tornado touched down, in force until 01:30 UTC.

The county was under a tornado watch, issued at 19:23 UTC and running to 02:00 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 Minneapolis radar (KMPX), 145 km away, was scanning. The volume nearest the touchdown began at 01:10 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.