A tornado warning is issued by the National Weather Service when either a tornado has actually been spotted by a trained spotter in the field (wouldn't you just love to have that job?) or there is evidence of one on the radar, such as a hook echo. Not to be confused with a tornado watch, which might sound scary but really means that the conditions for tornadic activity are present (read: there's a good chance that you will have a thunderstorm later on in the evening).

A tornado warning is to be taken seriously, however, I, a Kansas native, never have. When I was younger, I looked forward to a tornado warning being issued for my county because my family lived in a trailer (the last place you want to be during a tornado, and trailer parks seem to attract tornados like flies to honey), and when there was a tornado nearby, we'd drive to my grandma's house to wait out the storm in her basement. I loved any excuse to hang out at grandma's house, she always had candy, my parents would never let us have it. So when I was young, a tornado warning always meant eating candy and watching the brightly colored radar images dance across the television screen.