(meteorology) An indication that a tornado has been sighted in a viewing area.

Region in U.S., frequent tornadoes.

(meteorology) An indication that atmospheric conditions observed in and close to the watch area have created a significant risk for the development of severe thunderstorms capable of producing tornadoes.

(meteorology) A collection of tornadoes generated by the same weather system, at around the same or in a short or continuous period of time.

Tornado diagrams, also called tornado plots, tornado charts or butterfly charts, are a special type of Bar chart, where the data categories are listed vertically instead of the standard horizontal presentation, and the categories are ordered so that the largest bar appears at the top of the chart, the second largest appears second from the top, and so on.

A type of air raid siren used to warn of impending tornadoes.

Portable light source for emergencies.

Underground shelter from tornadoes, safe.

(meteorology) A tornado that is at least as wide as it is tall, on the ground level as well as on the cloud base, looking very massive, often opposed to a rope tornado.