Large tornado hits Chicago
A LARGE, destructive tornado tore through western suburbs of Chicago overnight, carving through neighbourhoods while lofting debris 5km high. The National Weather Service reported the twister damaged more than 100 homes and injured at least five people. The tornado spun up within a squall line that raced east through the metro area.
The Chicago suburbs of Woodridge and Naperville, southwest of the city, appeared to be hardest hit. As the storm swept through this area, the weather service warned of “a confirmed large and extremely dangerous tornado”.
“This is a particularly dangerous situation,” the weather service cautioned in a bulletin. “take cover now!”
Social media video captured power flashes as the funnel, cloaked by darkness and heavy rain, snapped electrical lines. “There is a tornado forming outside my window,” wrote the Twitter user who recorded the video.
Significant tornado damage was reported in Naperville in the vicinity of Ranchview Drive and Princeton Circle, where a “mass casualty incident” was reported due to multiple injuries and structural collapses.
The weather service in Chicago highlighted half a dozen areas it planned to investigate or survey for damage during the daylight hours yesterday. At least 75 000 people in Illinois and adjacent Indiana remained without power yesterday morning, according to PowerOutage.us.
There have been no immediate reports of fatalities associated with the storms.
Radar data suggests the tornado travelled upward of 15km through densely populated neighbourhoods of Naperville, Woodridge, Darien and Burr Ridge. It likely first touched down near the north side of the Springbrook Prairie Forest Preserve before making its way east and crossing near the intersection of 75th Street and South Washington Street.
From there, it largely paralleled 75th Street, eventually crossing the Veterans Memorial Tollway and Interstate 55 until its ultimate demise in the vicinity of Burr Ridge.
Significant storm damage was also reported in South Haven, Indiana, where the same line of storms that produced this twister may have dropped an additional tornado.
Severe weather had been in the forecast on Sunday, and the National Weather Service Storm Prediction Center included Chicago in a Level 3 out of 5 “enhanced risk” for severe weather. That’s where “large hail, severe/damaging winds, and a few tornadoes” were expected. It was initially unclear to what extent a tornado risk would remain present overnight as clusters of severe thunderstorms over Iowa, Missouri and western Illinois congealed into an arcing band of storms.
Doppler radar data revealed a pair of largely disorganised squall lines over northern Illinois between 9pm and 10pm local time. As storms approached Rochelle, the rear line weakened, allowing the leading batch of storms to become dominant. A telltale northern bookend vortex began forming south of Interstate 88 near Geneva. That marked the northern end of one segment of the squall.
Around 11 pm, a circulation gelled southwest of Naperville just south of West Ogden Avenue, going from barely noticeable to likely tornadic in one radar scan. The weather service quickly hoisted a tornado warning at 11.06pm.
By 11.09pm debris was visible on radar.
Radar also showed debris fallout south of downtown Chicago just before midnight local time.
“The nature of the radar signatures and damage indicates that this tornado could have potentially been an EF-2+ rated tornado,” the weather service in Chicago wrote.
The tornado was of unusual intensity for a QLCS, or “quasi-linear convective system” tornado. The term is used to describe bowing squall lines with short-lived, quick-hitting circulations. Ordinarily, QLCS tornadoes form rapidly, sometimes too quickly to trigger warnings. Their circulations are often shallow and develop from the ground up, making advanced detection of cloud-based rotation virtually impossible.