More than 77 million people from the Midwest to the southern Plains were under some form of tornado warning on Wednesday after multiple apparent twisters caused extensive damage in Illinois and Indiana. Northern Illinois remains the highest risk, with a "moderate" tornado warning for 2 million people in cities south and east of Chicago, including Joliet, Peoria and Bloomington. A marginal risk extends all the way down to Texas and Tennessee. A tornado emergency was declared in Knox, Indiana, on Tuesday, with the National Weather Service telling residents, "This is a life-threatening situation. Seek shelter now!" On Tuesday, the parent thunderstorm that produced tornadoes in northern Illinois and northern Indiana persisted for over 7 hours, along a 200-mile path. According to the National Weather Service, there were eight reports of tornadoes between the two states on Tuesday, and two in Texas.…