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.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:10:00 to 15-DEC-21 19:15:00 (CST-6)
Location: MYRTLE
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:11:00 to 15-DEC-21 19:15:00 (CST-6)
Location: LONDON
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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.

Tornado in STEELE, MINNESOTA
From 15-DEC-21 19:33:00 to 15-DEC-21 19:37:00 (CST-6)
Location: BLOOMING PRAIRIE
Tornado F-scale: EF0
Property damage: 105.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A narrow path of mostly tree damage was found just to the west of SE 89th Ave. An irrigation system was overturned, some farm outbuildings were damaged, and a small shed was tossed.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:10:00 to 15-DEC-21 19:11:00 (CST-6)
Location: LONDON
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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).

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:10:00 to 15-DEC-21 19:13:00 (CST-6)
Location: GORDONSVILLE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:15:00 to 15-DEC-21 19:21:00 (CST-6)
Location: HAYWARD
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

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.

Tornado in GOODHUE, MINNESOTA
From 15-DEC-21 19:51:00 to 15-DEC-21 19:54:00 (CST-6)
Location: BOMBAY
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado developed in Dodge County (see entry from NWS La Crosse). It spun up just south of the Goodhue/Dodge county border near 170th Ave and tracked northeast. It snapped pine trees, destroyed the top half of a barn, and lofted debris westward into a field. It ended around 100th Ave south of County 54 Blvd.

Thunderstorm Wind in GOODHUE, MINNESOTA
From 15-DEC-21 19:52:00 to 15-DEC-21 19:52:00 (CST-6)
Location: ROSCOE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A fee large branches were broken, including one partially across a road.

Tornado in GOODHUE, MINNESOTA
From 15-DEC-21 19:51:00 to 15-DEC-21 19:55:00 (CST-6)
Location: BOMBAY
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A tornado spun up south of Kenyon around County 11 Blvd and 50th Ave and continued northeast. It destroyed a few farm outbuildings and snapped several trees near 480th street. Debris was lofted west across 66th Ave.

Thunderstorm Wind in STEELE, MINNESOTA
From 15-DEC-21 19:39:00 to 15-DEC-21 19:39:00 (CST-6)
Location: STEELE CENTER
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A highway sign and an electronic message sign along Interstate 35 were blown down. Just to the southwest, new power poles were noted to have been erected. Damage was too scant to determine whether this had been from a tornado.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:22:00 to 15-DEC-21 19:22:00 (CST-6)
Location: MOSCOW
Magnitude: 64.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A large machine shed at a farm had about 1/4 of its roof blown away and its door blown inward (the door had been closed). A little farther to the north-northwest, 15 trees were broken or toppled. One of the trees fell on a truck. Damage was too scant to determine whether either site had sustained tornadic damage.

Thunderstorm Wind in BROWN, MINNESOTA
From 15-DEC-21 18:50:00 to 15-DEC-21 18:50:00 (CST-6)
Location: HANSKA
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A local mesonet weather station measured a wind gusts of 51 knots.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:08:00 to 15-DEC-21 19:08:00 (CST-6)
Location: GORDONSVILLE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

About one dozen trees were damaged. A storage shed lost a portion of its tin roof. Damage was too scant and scattered to consider this tornadic.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:00:00 to 15-DEC-21 19:00:00 (CST-6)
Location: CONGER
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A local mesonet weather station measured a wind gust of 52 knots.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:10:00 to 15-DEC-21 19:10:00 (CST-6)
Location: MYRTLE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Two old sheds at a farm collapsed, both of which had been open to the wind. This was just west of the tornado that developed and tracked near Myrtle.

Thunderstorm Wind in SCOTT, MINNESOTA
From 15-DEC-21 19:59:00 to 15-DEC-21 19:59:00 (CST-6)
Location: ELKO NEW MARKET
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A local mesonet weather station measured a wind gust of 59 knots.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:14:00 to 15-DEC-21 19:14:00 (CST-6)
Location: MYRTLE
Magnitude: 64.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A large machine shed lost part of its roof. However, an adjoining barn and another machine shed only sustained a threshold of visible damage.

Thunderstorm Wind in GOODHUE, MINNESOTA
From 15-DEC-21 19:54:00 to 15-DEC-21 19:54:00 (CST-6)
Location: BOMBAY
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A local mesonet weather station measured a wind gust of 59 knots.

Thunderstorm Wind in FREEBORN, MINNESOTA
From 15-DEC-21 19:16:00 to 15-DEC-21 19:16:00 (CST-6)
Location: OAKLAND
Magnitude: 68.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A home lost a number of shingles and a few trees. The damage was too scant, however, to determine whether this was a continuation of the Myrtle tornado.

Tornado in FARIBAULT, MINNESOTA
From 15-DEC-21 18:50:00 to 15-DEC-21 18:51:00 (CST-6)
Location: KIESTER
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A barn lost its roof. Large tree limbs were also downed. This tornado began in Winnebago County, Iowa (see entry from NWS Des Moines).

Thunderstorm Wind in SCOTT, MINNESOTA
From 15-DEC-21 19:59:00 to 15-DEC-21 19:59:00 (CST-6)
Location: LYDIA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A large tree was blown down near Fish Lake.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 18:58:00 to 15-DEC-21 19:01:00 (CST-6)
Location: ALDEN
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

The first damage observed was a bent road sign near the tornado origin point. A path of tree and utility pole damage continued to the northeast before ending just south of I-90. Several trees were uprooted.

Thunderstorm Wind in DAKOTA, MINNESOTA
From 15-DEC-21 20:06:00 to 15-DEC-21 20:08:00 (CST-6)
Location: FARMINGTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A few trees were blown down in southern Dakota County with the worst area in the city of Farmington.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:03:00 to 15-DEC-21 19:05:00 (CST-6)
Location: ALDEN
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This tornado developed to the east of Alden, damaging trees and a large building that housed farm equipment. It then continued to the northeast, damaging additional trees before dissipating in a field.

Thunderstorm Wind in LE SUEUR, MINNESOTA
From 15-DEC-21 19:20:00 to 15-DEC-21 19:25:00 (CST-6)
Location: CLEVELAND
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Between Cleveland and Le Center, isolated trees were blown down, with broken windows and roof damage to a garage.

Tornado in FREEBORN, MINNESOTA
From 15-DEC-21 19:11:00 to 15-DEC-21 19:13:00 (CST-6)
Location: HARTLAND
Tornado F-scale: EF2
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A fast-moving tornado touched down to the southwest of Hartland and moved into town, damaging numerous buildings, trees, and utility poles. The damage in the southern residential part of town was mainly tree and roof damage. As the tornado tracked into the center of town, more significant damage was observed to buildings along Broadway Street. The most significant damage was to two buildings along Broadway and Johnson in the center of town with significant damage to the walls of low-rise commercial buildings. More tree and roof damage was observed to the northeast with some branches observed along State Highway 13. The tornado dissipated to the northeast in a field with no further damage observed.

Thunderstorm Wind in WASECA, MINNESOTA
From 15-DEC-21 19:15:00 to 15-DEC-21 19:20:00 (CST-6)
Location: JANESVILLE
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several trees and large branches were blown down between Janesville and Waseca, with a street light damaged, and a few metal sheds and trampolines thrown.