 It was the deadliest tornado in the United States in 1972 and remains the deadliest tornado in the history of the Pacific Northwest.It was the first F3 tornado to strike Oregon since June 3, 1894, and was part of an outbreak of four strong tornadoes that struck Oregon and Washington that day.The National Weather Service tracked a very turbulent squall line of thunderstorms moving northeasterly across Portland, Oregon, the strongest of which was near the city of Tigard.