Winds up to 95 mph blew through Joliet on Saturday, causing the most damage of the storm system that spun out four tornadoes elsewhere in northern Illinois, according to the National Weather Service.
One tornado of 80 to 85 mph was confirmed north of Minooka, although no building damage was reported..
"The damage in Joliet was due to strong winds of 75 to 95 mph, so those winds were even stronger than the tornado (outside Minooka)," said Brett Borchardt, meteorologist at the National Weather Service station in Romeoville.
What hit Joliet was not a tornado, although the impact was similar in spots, he said.
"That's something we struggle to get across," Borchardt said. "You don't need a tornado to have a very bad day."
The winds ripped off the roof of an office building on the northeast corner of Route 30 and Theodore Street in Joliet.
It also did significant damage downtown, knocking down trees and streetlights on Chicago Street.
The city-owned Stadium Club building just outside of DuPage Medical Group Field was partially destroyed with a wall coming down as the roof was ripped off. There was roof damage at other downtown buildings.
Trees and utility poles across Joliet were blown down.
Despite the NWS finding that there was not a tornado in Joliet, the nature of the winds along with their velocity led many to believe there was.
"The wind came from all four directions in a two-minute period," Mayor Bob O'Dekirk said as he described his experience. "It was blowing west to east and then reversed, and then it was coming from behind the house from the north and then from the south."
The tornado outside Minooka caused damage while not hitting the town itself.
"There were several trees that were down," Borchardt said. "There was a car that was turned over, and there were utility poles knocked down."
The storm system generated four confirmed tornadoes in Illinois with the others being near Genoa, in Whiteside County and in Jo Daviess County, according to NWS.
"The hardest hit area looked like it was Joliet," Borchardt said.
The storm also dropped "torrential" rainfall at a rate of more than 2 inches an hour, Borchardt said.
The storm passed through in less than an hour. NWS had total rainfall measurements of 1.75 inches in Lockport and 1.25 inches in Minooka.
Many Joliet streets were flooded by the combination of heavy rain on ground already saturated from record rainfall in May while drainage outlets were clogged with tree debris because of the high winds.
At one point, all the viaducts downtown were impassable, but the water cleared away in a few hours.