National Weather Service
In 1955, two violent F5 tornadoes struck north-central Oklahoma and extreme south-central Kansas.
The first F5 tornado that had a track 25 miles long and around one half mile wide, barreled through Blackwell, Okla., where 20 were killed, 280 were injured, and around $8 million damage resulted. Around 400 homes were destroyed, many of which were swept from their foundations. Around 60 businesses were heavily damaged or destroyed. Prior to hitting Blackwell, the tornado caused $150,000 damage in Tonkawa. The lightning associated with the tornado was incredible. The vortex glowed and possessed arcs of glowing light.
The tragic Udall tornado soon followed. With a track 30 miles long and averaging one half mile wide, the tornado leveled most of Udall, killed 75, injured 270, and caused $2.25 million damage. The tornado also killed five children three miles northeast of Oxford, bringing the total number of fatalities to 80. It is still the deadliest tornado in Kansas history.
In 1917, an F5 tornado even larger than either the Blackwell or Udall tornadoes raced across south-central Kansas. It had a track 65 miles long and reached one mile wide. The tornado killed 23, injured 70, and caused around $600,000 damage from northwest Sedgwick to southeast Marion counties. The tornado started four miles northwest of Cheney and struck southeast Andale, where half of the town was damaged or destroyed and 12 were killed. The vortex then struck the southern edge of Sedgwick then proceeded to three miles northeast of Florence. In all, 118 structures were hit of which many vanished. Its average speed of 65 mph was the fastest on record until the Tri-State Tornado of March 18, 1925.
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In 2008, a massive EF5 tornado tore across Northeast Iowa. Reaching three fourths of a mile wide along a 43-mile long track, the vicious vortex possessed rotational velocities that reached 205 mph. Hardest hit was Parkersburg, where seven were killed and approximately $3 million in damage resulted. Two others were killed in the tiny town of New Hartford. In all, the tornado killed nine, injured 70, and caused around $6 million damage, which no doubt would have been much higher had the twister struck a more populated area. Regardless, it is the second deadliest tornado in Iowa history, exceeded by a huge F5 that tore through Charles City on May 15, 1968, when 13 were killed.