A tornado warning is an urgent public alert issued by weather agencies for areas in the path of a tornado or a severe thunderstorm capable of producing one, advising immediate shelter. These warnings are typically triggered by Doppler weather radar detecting rotation or by confirmed visual sightings from spotters, law enforcement, or the public, which is especially crucial when radar coverage has gaps. It is distinct from a tornado watch, which only indicates favorable conditions, and a warning can be issued even without a watch being active. The concept has deep roots, with early discussions in 1899 when the Chicago Tribune questioned the U.S. Weather Bureau, and Cleveland Abbe initially downplayed the need for them. By 1908, officials like Lieutenant John Park Finley suggested practical safety rules, while the Bureau proposed an early warning system using wires around cities to detect pressure changes. This historical evolution shows how tornado warnings have progressed from skepticism and basic observation to the sophisticated radar-based alerts used today.