HONOLULU — Maui hunkered down for heavy rains and powerful winds as a gradually weakening tropical storm barreled toward Hawaii, while Honolulu hoped it would be spared the worst. Forecasters said Wednesday that Tropical Storm Olivia could dump 5 to 10 inches (12 to 25 centimeters) of rain, with some places getting as much as 15 inches (38 centimeters). Maui Mayor Alan Arakawa urged residents to store drinking water and warned that they should plan for power outages, landslides, high surf, fallen trees and flooded roads. “Nature has a real funny way of not giving us advance notice,” Arakawa said. Olivia was about 95 miles (152 kilometers) east of Maui and packing winds of 45 mph (72 kph) early Wednesday.