PERTH, Australia (AP) - A severe tropical cyclone, packing winds of up to 180 mph, neared Australia's northwestern coast Tuesday, and hundreds of residents were evacuated from their homes. Cyclone John - a category-five cyclone, the most severe - was expected to cross the coast early Wednesday morning. Dangerous storm tides of up to seven yards were expected to cause heavy flooding in sparsely populated low-lying coastal regions, the State Emergency Services warned. Two evacuation centers capable of housing more than 1,500 people were set up in the center of the town of Karratha, 750 miles north of the Western Australia state capital, Perth. "We are certainly gearing up for the worst-case scenario," said State Emergency Services spokesman Steve Cable.