IndyCar driver Nolan Siegel was not cleared to race at Iowa Speedway because of a mild concussion suffered in a crash Saturday.

IndyCar Medical has not cleared Arrow McLaren driver Nolan Siegel to compete in Sunday's Farm To Finish 275 at Iowa Speedway after he crashed in Saturday's Synk 275.

After an afternoon filled with tornado sirens, lightning strikes, torrential rain and visible cloud rotation near Iowa Speedway, IndyCar canceled Friday afternoon practice.

Chad Hahn, warning coordination meteorologist at the National Weather Service, also confirmed a tornado did not touch down in Newton or Jasper County. He said there was a strong rotating wall cloud on the storm, which along with the rotation identified on radar prompted the tornado warning.

"It saved me a headache." IndyCar's aeroscreen was tested for the first time in race at Iowa Speedway five years ago.