Two central Wisconsin school districts canceled classes Thursday as a sheriff warned that violent storms and tornadoes forecast for the state could be the "granddaddy of all super cells." Other schools let out early.

The National Weather Service predicted very windy and warm conditions, with possible severe thunderstorms, damaging winds, large hail and isolated tornadoes, starting in the afternoon and continuing into the night.

By early afternoon, tornado watches were issued until 10 p.m. in western and northern Wisconsin, from Hudson and Chippewa Falls to Ashland and Hurley.

Chris Weisgram, a spokesman for the Stevens Point School District, said the Portage County Emergency Management Committee recommended late Wednesday that classes be called off at the district's nine elementary schools, two junior highs and one high school because of the forecast.

"Better safe than sorry," said Weisgram, adding he believed it was the first time the school had canceled classes because of a pending summer storm. "It is pretty risky having everybody congregated together."

Tomorrow River School District in Portage County also called off classes because of the forecast.

Lori Getter, a spokeswoman for Wisconsin Emergency Management in Madison, said she knew of no other schools that canceled classes because of the pending storm.

"It has been a few years since we had something where the threat was for the whole state," she said. "That does make this unique. Usually, it is sections of the state. ... We know there is going to be severe weather, but I can't tell you there will be tornadoes."

Several other school districts, including Darlington, Cuba City and Plattville, in southwestern Wisconsin closed early Thursday.

In Appleton, school officials said they would decide Thursday afternoon whether to cancel graduation ceremonies for three high schools planned that night.

The Wausau School District called off two eighth-grade class trips, including a bus trip to Noah's Ark in Wisconsin Dells, to keep students close to home in case of bad weather, spokeswoman Mary Ellen Marnholtz said.

Portage County Sheriff John Charewicz said forecasters' alarms about the storm moving east from the Great Plains caused emergency responders in his county to recommend school be closed Thursday and a Special Olympics competition for 3,000 athletes be canceled.

The forecasters called the weather front "the granddaddy of all super cells. So we are concerned," he said. "I don't know if people should be afraid. They should prepare for some inconveniences. Chances are they are going to be out of power for a couple of days if this arrives."

Charewicz said forecasters warned winds could reach 80 mph with golfball-size hail, but there was no guarantee the storm would hit Stevens Point.

"The critics are coming out and saying we are nuts and overreacted and maybe we have," he said. "I am willing to take that criticism. I have been here since 1975 and I have only seen the National Weather Service this alarmed about weather one time and that turned into a major blizzard in the 1980s."

Weisgram said Stevens Point's decision to cancel classes and force students to attend another day next week to make up for it generated a "mixed" reaction from parents Thursday.

Some are saying, "'The sky is falling. The sky is falling,' and things like that," he said. "It is a big decision to make parents have to take days off work. Ultimately, the safety of the students is No. 1."