STEVENS POINT, Wis. (AP) -- The threat of severe weather canceled classes at public and private schools in Stevens Point today.

Other school districts sent students home early, including Darlington, Cuba City and Plattville in southwestern Wisconsin.

Nearly half of Wisconsin's counties are under a tornado watch issued by the National Weather Service.

A super cell thunderstorm system is expected to hit this afternoon and evening hours.

The cell is strong enough to produce winds up to 75 miles per hour and up to two-inch hail stones.

Tonight's opening ceremony for the state's Special Olympics Summer Games being held in Stevens Point has also been called off.

Organizers made the decision to cancel after talking to the Portage County Emergency Operations Group and the National Weather Service.