EF1 tornado, Nelma to Scott Lake, Wisconsin, August 9, 2020

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

August 9, 2020

Touchdown

9:12 PM CDT (02:12 UTC)

Lifted

9:25 PM CDT (02:25 UTC)

On the ground

13 minutes

Path length

4.6 miles (7.4 km)

Path width

250 yards (229 m)

Deaths

0

Injuries

0

Property damage

$70,000

Counties

Iron, Florence and Forest counties

Touchdown point

45.982, -88.741

Lift-off point

45.989, -88.648

Record number

2008092012-01

22 damage points were recorded along this path by NWS GRB and NWS MQT, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 105 mph.

• large uprooted tree can be seen in woods
• Two trees in different directions. one uprooted ESE and one NE.
• Multiple reports from residents, Forest Service, local maint crews of damage continuing 4 to 5 miles back into Gold Mine Rd
• Photo taken by DNR Warden off Huff Creek Road.

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

An upper-level shortwave produced thunderstorms across north-central Wisconsin during the evening hours. Three tornadoes and wind damage was reported as these thunderstorms tracked through the area.

Increasing moisture and instability ahead of cold front approaching from the Northern Plains aided the development of strong to severe thunderstorms over portions of western Upper Michigan from the afternoon of the 9th into the morning of the 10th.

A tornado formed at 9:12 PM CDT in a remote forested area in extreme northeast Forest County, east of the town of Alvin. The tornado moved northeast to about 0.3 miles north of Ransdell Lake, then turned east, reaching maximum width before crossing Huff Creek Road. The tornado produced a path of tree damage (DI 27,28, DOD 3,4) before entering Florence County at 9:18 PM CDT. Peak winds were estimated at 105 mph.

The tornado that formed at 9:12 PM CDT in extreme northeast Forest County crossed the county line at 9:18 PM CDT. The tornado continued east, producing a path of tree damage (DI 27,28, DOD 3,4) in a remote forested area in extreme northwest Florence County, before crossing the Brule River into Upper Michigan at 9:20 PM CDT. Peak winds were estimated at 105 mph.

Tornado damage was confirmed by NWS storm survey team with numerous hardwood and softwood trees snapped off or uprooted on its path along and north of the Brule River in Iron County. Time of the damage was estimated from radar.

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 Slight Risk, with a 0.02 chance of a tornado within 25 miles. The outlook in force was issued at 19:55 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.

Land O Lakes (LNL), 44 km from the path, in the two hours either side.

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

The Marquette radar (KMQT), 107 km away, was scanning. The volume nearest the touchdown began at 02:10 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

12 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.