As many as 40,000 Commonwealth Edison customers lost power in the Chicago area overnight when severe thunderstorms moved through the northwest suburbs with winds as strong as 75 mph beginning around 2:10 a.m., according to a spokesman for the utility and the National Weather Service.

       By 8:30 a.m., John Schoen, a ComEd spokesman, said crews had gotten to about half the calls, with power already restored to some 20,000 customers. The main damage from the storm system, most of which hit north of the Wisconsin border, was downed tree limbs and power lines, according to meteorologists.

       Wednesday night a large storm system developed around north-central Wisconsin and far east-central Minnesota and morphed into a “thunderstorm complex,” or a line of thunderstorms, said meteorologist Lee Carlaw.

       Carlaw, who works in the weather service’s Chicago-area forecast office, said the complex “charged southward” overnight and “packed a bit of a punch” in northern Illinois and northwest Indiana.

       Forecasters Wednesday had warned of the possibility of a derecho in the Chicago area overnight but the city and suburbs seem to have been widely spared significant damage from severe weather that rolled through.

       Among the damage reports the weather service compiled overnight were:

       Downed power lines and a damaged vehicle along Forest Drive in Antioch. Large tree limbs down in Mundelein near Shaddle Avenue and Frenchie Drive. A tree was completely knocked over blocking Old Barrington Road in Lake Barrington. Wires were downed and trees were on fire in Maple Park in Kane County. A large tree was downed in Schaumburg, blocking Spring Valley Court. A large tree was downed blocking Wolf Road in Mount Prospect.

       Check back for updates.

       kdouglas@chicagotribune.com

       Twitter @312BreakingNews

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