EF0 tornado, Albertville to (Eau)Eau Claire Arpt, Wisconsin, July 21, 2020

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

July 21, 2020

Touchdown

8:12 PM CDT (01:12 UTC)

Lifted

8:29 PM CDT (01:29 UTC)

On the ground

17 minutes

Path length

3.5 miles (5.6 km)

Path width

25 yards (23 m)

Deaths

0

Injuries

0

County

Chippewa County

Touchdown point

44.904, -91.597

Lift-off point

44.910, -91.527

Record number

2007211912-01

3 damage points were recorded along this path by NWS MPX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF0. The highest wind the damage implies is 70 mph.

• Position based on video and photos from Jason Paul, Joe Slotevig, Melanie Metz, and Tanner Schaaf. Apparent dissipation point.
• Melanie Metz shows this touchdown point
• Beginning on Tanner's video. Large branches broken with debris noted.

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

During the afternoon of Tuesday, July 21st, a few thunderstorms developed along a frontal boundary over east-central Minnesota. Several spotters and storm chasers were following these storms as the storms moved into Wisconsin. ||The storm that moved into Polk County had a consistent funnel cloud associated with it with a brief tornado touchdown near Clear Lake and then again near Arland. Another storm developed across northern Dunn County and produced an EF0 tornado northeast of Wheeler. More storms developed over southeast Dunn and central Chippewa Counties to produce the majority of the damage. ||The worst damage occurred in the city of Cadott where numerous trees, power lines and a few structures were damaged as it moved through the town before dissipating.||The two tornadoes in Chippewa County had an average path length of 3 to 4 miles and an average width of 75 yards.

Several storm chasers and trained spotters observed a tornado that tracked just north of Highway 29, west of Chippewa Falls. The tornado moved across open fields and wooded areas, knocking down or lofting large branches and corn stalks. The tornado was not in continuous contact with the ground, but instead made contact several times during the course of its lifetime.

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. One was issued for the county at another hour that day.

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 Marginal Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 00:58 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.

Eau Claire (EAU), 8 km from the path, in the two hours either side.

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

The La Crosse radar (KARX), 124 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 2020 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

6 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.