Wisconsin Environment & Hazard Risk

An NWS Damage Survey team confirmed a tornado that originated in Outagamie County around 11:56 AM CDT continued moving south, entering northeastern Winnebago County around 12:00 PM CDT. The tornado produced EF1 damage by snapping and uprooting trees and damaging residential buildings just south of the Fox River. The tornado continued to widen and eventually strengthened again to EF2 damage just south of Palisades Drive by uplifting significant portions of the roof deck and collapsing garage doors to residences with winds of 120 mph. The tornado continued to strengthen and widen, reaching a width of 1400 yards and producing EF3 damage to a well-built low-rise brick building just north of Highway 10 in Menasha. At this location, significant damage occurred to the exterior walls and some interior walls with winds of 140 mph.||The tornado path then narrowed south of Highway 10 in Menasha to just below 1000 yards, producing pockets of EF2 damage along and just south of Midway Road by collapsing an entire roof with winds of 125 mph. EF2 damage was also observed east of Highway 10 near Airport Road with the collapse of the exterior walls of a small professional building and winds of...

Widespread flash flooding of streets, creeks, rivers, and low lying neighborhoods and homes occurred especially in New Berlin, Brookfield, Butler, Menomonee Falls, Elm Grove, and Muskego. Some of the more notable creeks or rivers that flooded were the Fox and Menomonee Rivers and their tributaries. The Butler Ditch, Jewel Creek, Root River, and other unnamed creeks also flash flooded. For all of Waukesha County, 3 homes were classified as destroyed, 310 homes and businesses sustained major damage, 221 with minor damage and 119 with affected damage. These damages were from a variety of 1st floor flooding, basement flooding, and foundation collapse. Residential sewage backups, and raw sewage released into rivers by many municipalities were common. A small number of complete road washouts and swift water rescues occurred, in addition to dozens of people stranded in their vehicles in deep, still water in low lying areas. More specifically, a partial road washout occurred on Lily Road in Menomonee Falls due to the flash flooding of a tributary of the Menomonee River. The large collapse of a Y-shaped intersection at Campbell Dr. and Campbell Ct. in Menomonee Falls also occurred due...

A massive chain-reaction pileup occurred in localized whiteout conditions along a stretch of I-41 in Neenah. A total of 131 vehicles were involved in the accident, 71 people were hospitalized and one person was killed after he exited his vehicle.

Widespread and numerous reports of flash flooding in streets, in addition to rivers, creeks, and streams across the southern two thirds of Milwaukee County. 1800 homes were classified as major damage or destroyed due to flash flooding of the Lincoln and Honey Creeks. Many instances of flooded basements across the impacted area. Six foundations collapsed into basements of homes in the 60th street neighborhood near Lincoln Creek, with two homes being condemned. Additional basement collapse reported in West Allis near Honey Creek. Many vehicles stranded in flood waters, with multiple water rescues conducted by the Milwaukee Fire Department. Water reached the bottom of car doors at Wisconsin State Fair Park. Reports of water inside vehicles along Delaware Avenue in Bay View. Multiple runway and taxiway closures reported at Mitchell International Airport and Timmerman Field from flooding. Impacts contribute to an estimated $65,813,855 in public and individual infrastructure damages countywide. Brief (30-45 minute total duration) rises into moderate flood stage along the Kinnickinnic River at Milwaukee and Oak Creek in South Milwaukee between 12:30 & 2:30 AM local time on August 10....

A brief period of snow showers with reduced visibility and accumulating snow resulted in two large vehicle pile-ups on both sides of I-39/90 near Beloit and Janesville. Approximately 85 vehicles were involved in the pile-ups and around 50 people were injured and treated in area hospitals. There were a few serious injuries. Both lanes of the interstate were closed for 10 hours.

A narrow band of heavy snow showers produced whiteout conditions and slick roads over portions of I-41 in Washington County for a period of 45 minutes to 90 minutes. Numerous multi-vehicle accidents were reported on I-41 near highway 144 and Cedar Creek Road, which included a crash involving 30 vehicles and another with 48 vehicles. 1 death was reported. 12 people were injured and sent to the hospital. Another 26 people were treated at the scene.