The warning affected a narrow, but densely populated area that included downtown Chicago. Flash flooding was seen from the downtown area through the West Side along the Eisenhower Expressway to Oak Park, as the slow-moving storm hovered stubbornly over the area.

A preliminary report into the deadly crash of an Air India jetliner in June is expected to be released by Friday, three sources with knowledge of the matter said, with one adding the probe had narrowed its focus to the movement of the plane's fuel control switches.

The Aircraft Accident Investigation Bureau (AAIB) is expected to release its preliminary report this week on the Air India plane crash in Ahmedabad, which resulted in the deaths of at least 260 people.