SYDNEY, Australia — Schools were closed, commercial flights were canceled and at least four major ports had been shuttered along Australia’s western shoreline on Friday in preparation for a severe tropical cyclone headed its way.

Tropical Cyclone Damien appeared as a Category 1 storm on Thursday in the northwest reaches of the state of Western Australia before moving offshore and gaining speed, said Brad Hall, a forecaster with the state’s Bureau of Meteorology. It was expected to make landfall on Saturday morning as a much stronger Category 4 storm, he said.

Mr. Hall said it would bring hurricane-force winds and a dangerous storm tide that could lead to severe flooding. “We’re expecting destructive winds of 150 kilometers per hour to develop as it approaches the coast,” he said, with wind speeds as high as 230 kilometers per hour — about 140 miles per hour — near the storm’s center on Saturday.