EF1 tornado, Mt Horeb to Pine Bluff, Wisconsin, May 21, 2024

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

May 21, 2024

Touchdown

7:49 PM CDT (00:49 UTC)

Lifted

7:54 PM CDT (00:54 UTC)

On the ground

5 minutes

Path length

4.6 miles (7.4 km)

Path width

75 yards (69 m)

Deaths

0

Injuries

0

Property damage

$1.1 million

County

Dane County

Touchdown point

42.991, -89.698

Lift-off point

43.046, -89.645

Record number

2405211849-01

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

• 3 trees snapped mid way up
• Numerous trees snapped at trunk or half way up. Facing NW
• Shed lifted and blown to the north. Front end of shed ended on opposite side so it doesn’t appear to be pushed.
• Pole shed lifted and completely destroyed. Pieces lofted into woods.

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

Lines and clusters of severe thunderstorms moved across southern WI from the late morning through the late evening as the passage of a warm front was quickly followed by a cold front. Straight-line winds accounted for fairly widespread tree limb damage especially over south central WI. Several reports of large hail were received while street flooding was reported in Madison. A couple brief EF1 tornadoes also occurred.

Tornado began near Springdale where it hit a farm. Two sheds were lofted into a nearby woods where numerous trees were damaged and placed in a crisscross manner. The tornado then crossed Highway 18-151 while tracking to the northeast. It hit an outbuilding on County Rd P which caused it to shift off its foundation. Further north, it uprooted or snapped about 20 mature trees at a farmstead on County Rd P. The tornado then went across Cty P and ended near Valley Spring Rd and County Rd J.

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

31 minutes of warning. NWS MKX issued a tornado warning for this county at 00:18 UTC, 31 minutes before the tornado touched down, in force until 01:00 UTC.

The county was under a tornado watch, issued at 21:00 UTC and running to 04:42 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 19:57 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.

Middleton (C29), 16 km from the path, in the two hours either side.

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

The Milwaukee radar (KMKX), 91 km away, was scanning. The volume nearest the touchdown began at 00:46 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 2024 tornado in WisconsinEvery tornado in Wisconsin since 1950Warnings in force in Wisconsin nowThe forecast where you are

42 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.