NOAA NOAA severe tornadoes Historical Records and Trends Tornado activity 155 tornadoes 1991年から2010年までのデータ 1950s tornadoes numbers of violent tornadoes in the U.S. over time This NOAA’s Historical Records and Trends page "U.S. Tornado Climatology" as NOAA itself says Tornades NOAA https://www.ncdc.noaa.gov(...)o-climatology/trends Check this report Tornado activity With tornadoes Tornado activity more tornados This Historical Records and Trends tornadoes are not increasing tornadoes National Climatic Data Center NOAA NOAA gives a similar explanation on its website NOAA NOAA well accepted Tornado activity unchanged or slightly declining NOAA’s Historical Records and Trends page tornadoes are not increasing unchanged or slightly declining NOAA near-constant decline since the 50’s near-constant decline since the 50's NOAA’s climate information website "U.S. Tornado Climatology" more likely to be spotted With tornadoes unchanged or slightly declining last 55 years With tornadoes Tornado.s NOAA well accepted Historical records and trends last 55 years claro 1950s well accepted last 55 years NOAA With tornadoes "U.S. Tornado Climatology" 1991年から2010年までのデータ tornadoes are not increasing Historical records and trends US tornado activity more tornados tornadoes are not increasing