The National Weather Service said Monday the tornado that touched down in Naperville, bringing winds of nearly 140 miles per hour, was ranked an EF-3 on the Enhanced Fujita Scale, marking 45 years since a "significant" tornado ravaged portions of DuPage County.
As defined by the NWS, a "significant" tornado is a twister of EF2/F2 intensity or greater or a tornado that caused any fatalities or at least 10 injuries. The Fujita scale estimates wind speeds based on damage intensity and ranks tornados from 0-5.
In 2007, the NWS adopted the EF Scale, which “has to do with how most structures are designed” and aligns wind speed more closely with associated storm damage, according to the government agency.
Prior to Sunday's tornado, the most recent notable tornado in DuPage County - an F4 - occurred on June 13, 1976, and resulted in two deaths along with 23 injuries. The storm traveled on an "8-mile meandering path" through both Cook and DuPage counties and caused $13 million in damage, the NWS said.
Just months earlier, two F3 tornadoes were reported on the same day. One twister on March 12, 1976 tore through both Cook and DuPage counties, killing two people and injuring 66 others. Three people were injured in the other incident.
Here are the other "significant" tornadoes that occurred in the past 100 years in DuPage County:
- Sept. 11, 1925 - F2 - 1 injured
- Sept. 26, 1959 - F2 - No injuries or death - DuPage and Cook counties
- May 26, 1965 - F2 - 11 injuries - Addison to O'Hare Airport
- April 19, 1966 - F2 - 3 injuries - Near Lisle
- August 24, 1971 - F2 - 2 injuries - Naperville
- July 17, 1972 - F2 - No injuries or deaths - Glen Ellyn
- April 21, 1973 - F2 - No injuries or deaths - Wheaton