The National Weather Service reports the tornado that ripped through four northeastern Iowa counties Sunday covered a 43 mile path and, at one point, measured 1.2 miles wide. The storm is blamed for seven deaths and 50 injuries. At least 350 homes were destroyed.
Meteorologist Marc Russell says the strength of a tornado is measured with the Enhanced Fujita, or EF scale. He says most tornadoes in Iowa are below EF2 in intensity, but this latest twister is probably at least an EF3. An EF3 tornado can carry wind speeds between 136 and 165 miles an hour.
“Once we get above 165 miles per hour, that’s the low end of EF4 scale. That’s a range of 166 miles an hour up to 200,” Russell said. An EF5 tornado packs winds above 200 miles per hour. A storm survey team with the National Weather Service is still trying to determine how to categorize Sunday’s tornado. If it’s labeled an EF4, it would be the first one of that magnitude to hit Iowa since 1999.
“EF3 damage usually causes houses to be damaged to the point of walls collapsing, entire roofs blown off and things of that nature. Once you get into the EF4 range, that can cause complete destruction of homes,” Russell said. The last EF4 tornado in Iowa killed two people and injured 16 in western Iowa.
That twister touched down May 16, 1999 in Harrison County between the towns of Missouri Valley and Logan. Since 1950, Iowa has experienced 42 EF4 tornadoes and five EF5’s. The last EF5 to occur in Iowa happened in Boone and Story Counties on June 13, 1976.