According to preliminary damage assessments by the National Weather Service, at least seven tornadoes touched down in areas west of the city of Chicago on Monday evening, including at least three twisters classified as EF-1 on the Enhanced Fujita Scale.
NWS officials say that EF-1 tornadoes touched down in McHenry, Sycamore and Burlington on Monday afternoon and into the evening hours.
Officials say that all of their findings are preliminary, including the EF-1 classification for the tornado that touched down near Sycamore. That tornado track may be split into two or three separate tracks after further examination of debris trails and other information, according to NWS.
Two other tornadoes, classified as EF-0, touched down to the north and to the south of the town of Esmond, and two more twisters, classified as EF-U, touched down to the south of Kirkland and in the town of Paw Paw.
The “EF-U” designation is used when a tornado doesn’t produce damage that can be used to determine its wind speed, according to NWS officials.
The “Enhanced Fujita Scale” is used by meteorologists to determine the strength and destructive power of tornadoes. A tornado with an EF-0 rating is estimated to have three-second wind gusts of 65 to 85 miles per hour, while a tornado with an EF-1 rating is estimated to have three-second gusts of 86 to 110 miles per hour.
All seven tornadoes were part of an outbreak of severe weather Monday that mainly targeted the far western suburbs of Chicago, including in DeKalb, Kane, McHenry and DuPage counties.
Reports of damage were widespread, but no injuries have been reported at this time.