EF1 tornado, Tiffany to Johnstown, Wisconsin, April 17, 2026

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, as surveyed

EF1, preliminary

Date

April 17, 2026

Touchdown

6:02 PM CDT (23:02 UTC)

Lifted

6:05 PM CDT (23:05 UTC)

On the ground

3 minutes

Path length

1.9 miles (3.1 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

County

Rock County

Touchdown point

42.606, -88.943

Lift-off point

42.633, -88.934

Highest wind the damage implies

90 mph

Surveyed by

NWS MKX

The office's name for it

La Prairie

Survey last edited

April 29, 2026

Record number

None yet. SPC numbers 2026 in the spring of 2027.

Brief tornado that caused damage near Maple Ln southeast of Janesville. Storm chaser video confirmed a brief tornado in this area. Damage further west and east of this point is from rear flank downdraft.

Written by NWS MKX in the NWS Damage Assessment Toolkit. A survey is revised as better evidence arrives.

76 damage points were recorded along this path by NWS LOT and NWS MKX, in the Damage Assessment Toolkit the survey teams carry. The strongest indicator was rated EF1. The highest wind the damage implies is 110 mph.

• Two irrigation systems displaced/rolled. Not a DI. Damage is all to the southeast.
• About 10 trees uprooted or snapped. Going southeast. From different storm?
• Doors blown in, roofing blown off. Sheet metal noted in field to the south.
• Completely destroyed, taken to the southeast.

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

A round of severe thunderstorms and flash flooding occurred as a strong cold front approached and tracked across southern WI. More specifically, supercell thunderstorms developed from northeast IA into southwest WI and far southern WI during the late afternoon and evening hours. Eventually these storms transitioned to a squall line which had a number of tornadoes associated with it, as it tracked through southeast Wisconsin. Flash flooding affected much of the same region especially in Janesville. Many large hail reports and a small number of downburst damaging wind reports were also received.

Brief tornado that caused damage near Maple Lane southeast of Janesville. Storm chaser video confirmed a brief tornado in this area. More widespread damage occurred west and east of this track due to downburst winds.

Brief tornado went through Emerald Grove, destroying a barn and causing damage to an antique store. Significant tree damage along the path as well with debris lofted well to the ENE from the structures.

Multivortex tornado documented southwest of Richmond. Multiple sheds with sheet metal damage along County Highway M before entering Walworth County.

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

24 minutes of warning. NWS MKX issued a tornado warning for this county at 22:38 UTC, 24 minutes before the tornado touched down, in force until 23:30 UTC.

The county was under a tornado watch, issued at 17:42 UTC and running to 02:15 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 Enhanced 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 19:53 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.

Janesville/Rock (JVL), 8 km from the path, in the two hours either side.

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

The Milwaukee radar (KMKX), 50 km away, was scanning. The volume nearest the touchdown began at 23:00 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 2026 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

88 more have been surveyed in the United States that day, so far.

All 89 of them

Ratings are the survey's, read off the damage rather than measured; the rating scale is above. A survey can be revised, so the rating, the path and the casualties can all still change.

NWS Damage Assessment Toolkit, the record the survey teams file from the damage, and NOAA Storm Prediction Center storm reports. Neither is the official database for 2026, which SPC publishes in the spring of 2027.