Draft:2021 Naperville–Woodridge tornado

Draft:2021 Naperville–Woodridge tornado

EF3 damage to a home in Naperville, Illinois.
Meteorological history
Formed	June 20, 2021, 11:02 p.m. CDT (UTC−05:00)
Dissipated	June 20, 2021, 11:25 p.m. CDT (UTC−05:00)
Duration	23 minutes
EF3 tornado
on the Enhanced Fujita scale
Highest winds	140 mph (230 km/h)
Overall effects
Fatalities	0
Injuries	11
Areas affected	Southern DuPage County and Willow Springs, Illinois
Part of the tornadoes of 2021

In the evening hours of June 20, 2021, an intense tornado affected the Chicago suburbs of Naperville, Woodridge, Darien, Burr Ridge, and Willow Springs in DuPage and Cook Counties in Illinois. The tornado struck well after dark, had a path length of 14.8 mi (23.8 km) and reached a width of 600 yd (550 m), as well as causing 11 injuries. It was the strongest tornado in the Chicago metropolitan area since 2015's Coal City tornado, and the first major tornado in DuPage County since the 1976 Lemont tornado.

Meteorological synposis

The Storm Prediction Center had issued an Enhanced (3/5) risk for severe weather over extreme eastern Iowa, northern Illinois and Indiana, southern Michigan, and extreme northwest Ohio for the potential of severe weather, focused on damaging straight-line winds, with the potential for isolated large hail and non-significant tornadoes. A conditional threat for the development of supercells existed over northern Illinois, with forecasters noting the difficulty of predicting any large-scale threat due to numerous existing outflow boundaries in the risk area.

Earlier in the day, an afternoon mesoscale convective vortex system had moved through Missouri, central Illinois, and northern Indiana, however a second round of storms was expected to reach the Chicago metropolitan area by midnight that night. At 9:40 p.m. CDT, a severe thunderstorm watch was issued across most of northeastern Illinois and extreme northwestern Indiana. The main threat was clusters of storms producing severe downburst winds, with only a low (20%) risk for a tornado, and a very low (5%) chance of a significant tornado.

Tornado summary

A poorly anchored house that was leveled at low-end EF3 intensity on the southeast side of Naperville.

A tornado warning was issued for much of Kane and DuPage counties at 10:43 p.m., including Aurora, Batavia, West Chicago, and western portions of Naperville, as the National Weather Service office in Romeoville tracked two areas of rotation in the area; one over Aurora, and another near Maple Park. The tornado first touched down at 11:02 p.m. in the Springbrook Prairie Forest Preserve, outside of the initial warning polygon, and the first tornado warning for the tornado itself was issued at 11:05 p.m. for radar-indicated rotation. Around this time, the tornado caused intense tree damage to the forest preserve before moving to the Quall Drive area at EF1 intensity. Despite causing significant tree damage, most structural damage was a result of falling trees until the tornado reached the intersection of Killdeer and Bailey, where EF1 damage to houses occurred. At 11:06 p.m., the tornado crossed the West Branch DuPage River, and continued moving eastward. At around 11:09 p.m., the tornado intensified to EF2 intensity and approached Princeton Circle in Naperville, where the tornado caused the collapse of a poorly-anchored house, an area of low-end EF3 damage with wind speeds estimated at 140 mph (230 km/h). This was the most intense damage produced by the tornado.

The tornado warning issued for DuPage, Cook, and Will counties.

At 11:15 p.m., the tornado crossed over Interstate 355 near Woodridge, and one minute later, the National Weather Service upgraded the initial tornado warning to particularly dangerous situation wording, as meteorologists had confirmation that the tornado, now described as "large and extremely dangerous", was moving into Darien. The warning text also stated that "[r]adar confirms debris with this tornado moving over populated areas". Two minutes later, at 11:17 p.m., a correlation coefficient scan from KLOT indicated debris lofted up to 20,000 ft (3.8 mi; 6.1 km) into the air.

Surveys conducted from an ABC-7 helicopter showed large trees uprooted and blown up to 40 ft (12 m).

Aftermath

A total of 29 properties across Lisle Township were declared uninhabitable. By June 2 the next year, 22 were still in varying stages of repair. On June 22, Alicia Tate-Nadeau, director of the Illinois Emergency Management Agency, toured storm damage in Naperville and Woodridge with DuPage county officials. On June 27, Brian McDaniel of the Illinois River Valley Red Cross met with county officials and opened the Multi-Agency Resource Center, where over 1,000 volunteers assisted to provide aid to those affected by the tornado. The center was opened for two days.