HONOLULU, Aug. 16 -- Near South Point on Hawaii's Big Island, a driver died Saturday when Lala's storm-force winds and flooding made the roads impassable. The rest of the island was faring little better.

By Sunday morning, the storm, downgraded from Category 1 hurricane to tropical storm as its eyewall brushed through the southernmost reaches of the chain, had knocked out power to more than 124,000 homes across the state. At the summit of Mauna Kea, instruments recorded gusts topping 140 miles per hour. The official sea-level winds were 70 miles per hour. What Hawaii's terrain did to them was something else entirely.

Two homes in Naalehu, in the Big Island's Kau District, were swept away by flash flooding Saturday evening. Roads across ...