The Western Wisconsin Derecho was a severe storm (or more accurately, a Derecho) that occurred through several counties of Western Wisconsin on July 15, 1980. It caused nearly $160M in damage (1980 dollars)(including severe damage to Menards headquarters) and is still referred to as “The July 15th (1980) Storm,” “July 15th, 1980,” or simply “The Storm.”

The best part is, the storm was all Minnesota’s fault!

That’s a half truth. The storm formed in MN, picked up speed, and did most of it’s damage in Wisconsin.

The storm developed during the heat wave of 1980. Eight days prior to the storm, MN had experienced highs above 90°F, which primed the fuse for a storm.

As the storm raced through St Croix, Pierce, Dunn, Eau Claire, Chippewa, and Clark counties, it caused a band of damage more than 20 miles (30 km) wide. A maximum wind speed of 110 mph (177 km/h) was recorded at the Chippewa Valley Regional Airport, while 100 mph wind was recorded in the city of Eau Claire. At 9:39 p.m., WEAU-TV broadcast an alert from the National Weather Service about one of several tornado warnings that evening for Eau Claire County; moments later, the station lost power and went off-the-air.

Although much of the storm’s damage was caused by straight-line winds a total of 10 tornadoes (ranging from power of F0 to F3) were reported.

Also, there was controversy because although the Feckless Jimmy Carter declared it a disaster area, due to the massive influx of Cubans into the country, the Mount St Helens eruption of 18 May, the severe tornadoes in Grand Island, Nebraska in June, and flooding in western Pennsylvania during August, the FEMA rules changed, covering only 75% of the damages, leaving WI with $800,000 of disaster to cover.

Source: My hero