As Greenfield, Iowa, assesses the town’s damage, a wind farm near the area also took a hit from Tuesday’s tornado and severe storm.
Drone video footage from Reed Timmer, a storm chaser and meteorologist, captured a tornado in Iowa snapping a wind turbine in half and causing damaging others. Timmer described the footage as showing an “up-close helical suction vortex action” tornado as it spanned the Iowa field.
Watch as an Iowa tornado destroys a wind turbine
The drone footage starts by showing the tornado run through a residence as it crosses an Iowa field. As it moves further, it creeps closer to the wind turbine farm instantly snapping one in half with its force. The upper half of the wind turbine falls to the ground as the tornado continues across the field for the seven-minute video.
How many wind turbines were damaged from Tuesday’s tornado?
MidAmerican Energy and Vestas US say 10 wind turbines were destroyed in the storm that swept through Adair and Adams counties Tuesday. MidAmerican said a tornado struck five turbines its Orient wind farm and one in its Arbor Hill wind farm. Both are located in Adair County near Greenfield, which experienced widespread damage and fatalities from a tornado.
Vestas said four turbines were destroyed in Adams County.
MidAmerican believes tornadoes in Adair County “directly struck our wind turbines,” based on review of several social media posts, Tina Hoffman, a MidAmerican spokeswoman, said in an email.
MidAmerican turbines registered windspeeds over 100 miles an hour as the tornadoes approached, and the utility lost contact with its sensors, Hoffman said.
The company, owned by Warren Buffett’s Berkshire Hathaway, said the no technicians at the sites were injured, sheltering “in place at our operation and maintenance facilities,” all of which are all equipped with storm shelters, Hoffman said.
No one was injured by the toppled wind turbines, either, she said.
“This was an unprecedented impact on our wind fleet, and we have operated wind farms since 2004,” she said. “We have experienced only one other instance of a wind turbine collapse, which was also caused by a tornado.”
She said manufacturers design wind turbines to withstand Iowa’s changing weather conditions, including severe thunderstorms and high wind events. “As we’ve seen from the damage sustained throughout several Iowa counties, few structures can withstand a direct hit by a powerful tornado such as what we experienced on Tuesday,” she said.
MidAmerican said it’s inspecting all its wind operations in the area “out of an abundance of caution,” before resuming operations.
What does ‘helical suction vortex’ mean?
Helical more broadly describes a spiral, according to Merriam-Webster’s Dictionary. Suction vortex means a small but intense vortex within a tornado’s circulation, according to the National Weather Service. Extreme damage from violent tornadoes is often attributed to the suction vortices.
How tall was the wind turbine struck by a tornado in Iowa?
It’s not known exactly what type of wind turbines were hit by a tornado in Iowa. Most turbines owned by MidAmerican are less than 150 meters tall.
The majority of turbines in the area are Vestas V-120 models, which usually stand around 90 meters tall. The rotors are 120 meters in diameter and they are typically made from a carbon fiber reinforced by epoxy and glass fiber, according to Vestas. The full installation can weigh over 400 tons and the rotors alone can weigh as much as 65 tons, according to Vestas.
Others are models are similar in size and dimensions.
Where are the wind turbines that were hit by a tornado in Iowa?
The tornados in Timmer’s video were somewhere near Greenfield, according to his YouTube caption on the video. While damage did occur in Adair County, there was no significant damage to any of MidAmerican’s wind turbines in Adams County just south of Adair.
Kate Kealey is a general assignment reporter for the Register. Reach her at kkealey@registermedia.com or follow her on Twitter at @Kkealey17.
