this country has experienced. An EF-4 or EF-5 tornado hitting a major metropolitan area could dwarf the damage and loss of life from Hurricane Katrina in 2005, killing thousands; maiming tens of thousands with chronic, lifelong injuries, sparking a $ 5-15 billion trail of rubble. Tornado intensity trends since 1950 below: The Weather Underground's Dr. Jeff Masters speculates the last two years may have been the most severe in America's history, dating back to 1816 . Something has changed. It may be a temporary aberration, but an apparent eastward shift in Tornado Alley may threaten millions of Americans who still believe a tornado is something only experienced in Kansas. But Chicago, Nashville, Atlanta and Washington D.C.? It can't happen there, right? Wrong. The trends are troubling, but if you keep your situational awareness, have multiple safety nets, take advantage of new tornado warning technology, don't depend on the sirens, draft a Tornado Action Plan with your family -- and take every single tornado warning seriously, you'll breathe a little easier the next time angry thunderstorms rumble overhead. Loading comments... There's no evidence that tornado occurrence has changed, once reasonable assessment of the changes in reporting are taken into account. Violent tornadoes have always occurred in everywhere east of the Rockies. One of the things that all of the biggest outbreak days in US history (1884, 1908, 1920, 1932, 1974, and 2011) share in common is large number of deaths in Alabama. None of the tornadoes in the Dallas area were