After severe weather caused a ground stop, and evacuation of the control tower, more than 300 flights were canceled Monday at OHare International Airport Chicago.The National Weather Service was monitoring severe storms in Illinois all day Monday and into Tuesday night. The Weather Service reported that a tornado was confirmed in Arlington, Ill. (about 100 miles southwest) of Chicago at 7:17 p.m.A severe thunderstorm warning was issued by the Weather Service for the north and northwest areas of Chicago, including OHare Airport, about an hour later. According to the Weather Service, winds up to 60 mph, penny-sized hail, and tornadoes were possible due storms moving through the area.The Weather Service tweeted that they are monitoring the strengthening rotation over OHare Airport. This was just moments after the severe storm warning was issued.
