When a tornado is spotted what is the warning that is put out?

A tornado watch is given out if general weather conditions favor the formation of tornadoes over the next few hours. A PDS (Particularly Dangerous Situation) tornado watch may be issued if conditions favor the formation of strong to violent tornadoes. A tornado watch usually covers an area at least the size of a state.

A tornado warning is issued if a tornado has been spotted or detected or the threat of one is imminent. A tornado emergency is an informal variety of tornado warning meaning that a large tornado is approaching a populated area and is expected to cause major damage. A tornado warning usually covers an area about the size of a county.