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• • • Anoka County Multi - Jurisdictional All Hazards Mitigation Plan Fuiita— Pearson Tornado Scale Description Table F- Scale Damage Winds (mph) Description F -0 Light 40 -72 Chimney damage, tree branches broken F -1 Moderate 73 -112 Mobile homes pushed off foundation or overturned F -2 Considerable 113 -157 Considerable damage, trees down, mobile homes demolished F -3 Severe 158 -206 Roofs /walls torn down, trains /cars overturned F -4 Devastating 207 -260 Well- constructed walls leveled F -5 Incredible 261 -318 Homes lifted off foundation and carried considerable distances F -6 Inconceivable 319 -379 Unknown The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more. Damage paths can be in excess of 1 mile wide and 50 miles long. Even with advances in meteorology, warning time for tornadoes is short or impossible. Tornadoes can occur in any state, but are more frequent in the Midwest, Southeast and Southwest. Tornado season is generally March through August, although tornadoes can occur at any time of year. They tend to occur in the afternoons and evenings. Over 80% of all tornadoes strike between noon and midnight. The city of Andover experienced tornadoes in July of 1983 and September of 2005. In the 1983 event 64 structures had significant damage and hundreds of trees were destroyed. There were citywide power outages and much debris cleanup. The 2005 impact was even greater, again citywide power outages occurred and hundreds of trees were destroyed. In the 2005 event over 1000 roofs were replaced 300 houses Minnesota Tornadoes by County 1950 -2002 LO 9 © 10 -10 020.29 ❑ 30 or more Iomaooes Srwrro. Nstonsl CLmattc Data Canto, had to be re -sided and 50 additional homes had extensive damage. The City of Blaine suffered significant Tornado damage form Tornado events in 1976 and 1998 and minor damage from a tornado in 2005. In the 1976 and 1998 incidents the majority of damage in both occurrences was sustained on the eastern side of Blaine. In 1976, the Centennial High School Building sustained heavy damage and in 1998 wide spread damage was sustained in the residential areas in the same part of the city. Between both occurrences over $500,000 worth of damage was sustained. Although the two- documented tornado touchdowns occurred in the eastern part of Blaine a tornado could cause damage anywhere. Due to climate and geographic location the likely occurrence of tornados can be a frequent occurrence for the City of Blaine. With Blaine's rate of growth and construction practices loss impact from future tornados would be more significant than what has been seen historically.