Wisconsin tornado outbreak, 15 years later: Weather History Wednesday

Beyond The Forecast

WISCONSIN (WFRV) – Fifteen years ago this week on August 18, 2005, Wisconsin broke the record for the most tornadoes in a single day in state history.

The total amount of tornadoes tallied up to 27 breaking the previous record of 24 tornadoes on May 8, 1988. Within the National Weather Service (NWS) Green Bay coverage, five of those tornadoes were confirmed in Northeast Wisconsin.

The day began with a developing low-pressure system in southeastern Minnesota. Dew points were in the 70s for most of Wisconsin as a strong warm front closed in on the area. Additionally, daytime heating ahead of the system provided the instability needed to fuel these storms.

The cold front attached to the low pressure area caused rapidly strengthening thunderstorms to develop to the east of it. Those storms then encountered strong mid-level shear which enhanced the ability for the storms to produce tornadoes. The first tornado watch of the day was issued by the Storm Prediction Center (SPC) at 2:51 p.m. CDT.

The strongest tornado of the day was an F3 tornado that tracked through Stoughton. The long track tornado lasted 20 miles through Jefferson and Dane counties with a maximum width of a half-mile. One death was reported with this single tornado.

In Northeast Wisconsin, there were two reported F1 tornadoes and three F0 tornadoes. One of these F1 tornadoes was just northeast of Wrightstown in Brown County, the other F1 tornado came just near Manitowoc where the damage path lasted over 1.6 miles.

Of those 27 tornadoes using the old way of rating tornadoes through the Fujita scale:

  • 11 tornadoes were rated as F0 (3 in NE Wisconsin), winds between 40-72 mph
  • 14 tornadoes were rated as F1 (2 in NE Wisconsin), winds between 73-112 mph
  • 2 tornadoes were rated as F2, winds between 113-157 mph
  • 1 tornado was rated as F3, winds between 158-206 mph

This year, Wisconsin saw three tornadoes, including a waterspout over Lake Winnebago, during Father’s Day weekend.

As of August 18, Wisconsin has seen a total of 17 tornadoes throughout the state in 2020. In Northeast Wisconsin, three have been recorded in Winnebago County this year. Naturally, it begs the question, what causes a tornado? It is a loaded question that WFRV Storm Team 5 Meteorologist Ryan Morse answered here.

Peak tornado season across Wisconsin typically comes in June. Annually, the state averages 23 tornadoes per year. In the event of severe weather, be sure to stick with Storm Team 5 on-air, online, and on our app:


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