It’s now been 20 years since the largest single-day tornado outbreak in the state of Wisconsin, 20 years since a deadly F3 tornado tore through the city of Stoughton. Hundreds of homes were destroyed and thousands of lives impacted in a storm that many Wisconsin residents will never forget.
The Set Up:
The weather on August 18 of 2005, was one of those days that felt like a storm was brewing. Though temperatures were only in the mid-70s to low-80s, the humidity was oppressive with dew points in the high 60s and low 70s, and there was a strong southerly wind.
A center of low pressure and a potent warm front moved in from the west and swept across the southern half of the state. Storms began to spark as wind shear along the frontal boundary met the unstable, hot, and humid environment. You can take a closer look at the surface analysis of weather conditions throughout the day using the NOAA Weather Prediction Center’s archives.
The Twisters:
The event resulted in 27 tornadoes across the state, scattering from Vernon County in the southwest to Dane County in south-central, and up to Brown County in the northeast. This surpassed Wisconsin’s previous largest outbreak of 24 tornadoes, the Mother’s Day Outbreak of May 8, 1988.
| Wisconsin’s Largest Single-Day Tornado Outbreaks | |
|---|---|
| Date | Number of Tornadoes |
| August 18, 2005 | 27 |
| May 8, 1988 | 24 |
| July 3, 1983 | 22 |
| August 28, 2018 | 19 |
| June 8, 1993 | 18 |
Many of the tornadoes that occurred that day were ranked low on the Fujita Scale (updated to the Enhanced Fujita Scale in 2007): 11 were rated F0 with winds under 72 miles per hour, and 13 were rated F1 with winds under 112 miles per hour. Though often overlooked due to the lower ranking, an impressive six tornadoes tore through Fort Atkinson (Jefferson County) in just 45 minutes.
Three of the tornadoes in the outbreak were more severe: an F2 near Lake Wisconsin in Columbia County, an F2 that crossed from Vernon to Richland County near Viola, and the F3 in Stoughton in southeastern Dane County.
The Stoughton Twister
By the Fujita Scale, the Stoughton tornado would have estimated maximum winds of 158 to 206 miles per hour — the equivalent of a high-end EF3 on the Enhanced Fujita Scale. Tornadoes of that strength are uncommon in Wisconsin, making up only four percent of the state’s tornadoes since 1955.
This F3 tornado first touched down in Dane County just north of Oregon at 6:15 PM and raced eastward just south of Lake Kegonsa. It was on the ground for 20 miles before finally lifting near Lake Koshkonong in Jefferson County at 7:08 PM.
The Aftermath:
The Stoughton tornado alone severely damaged or destroyed over 200 houses, injuring more than 20 people. One man died after his chimney fell on him as he sought shelter from the storm. The destruction in Stoughton was estimated to cost $42 million.
In the wake of the F2 tornado in Richland County, one resident was quoted as saying that all the trees in the town were gone. Hundreds of homes and structures were impacted, amounting to over $3 million in damages. No injuries were reported in the village or nearby areas.
Fort Atkinson was littered with debris from trees, farm sheds, and grain bins following the city’s six twisters. Roughly 20 homes, along with some businesses, reported minor damage.
Sparking Change:
The destruction of the storms on August 18 shocked Wisconsin residents and moved some of them to action. In 2015, Dane County allocated nearly $4 million to improve communications between first responders with the construction of new radio towers, new paging transmitters, and new communication channels to be used for coordination during emergencies. Also in 2015, federal funding allowed for one of the first mobile home park storm shelters to be built in Madison.