Howling winds, pelting rain and heavy snow pummeled California, toppling trees, flipping big rigs, cutting power to more than a million people and threatening mudslides in fire-scarred areas. Flights were grounded and highways closed in Northern California on Friday as gusts reached 80 mph (nearly 130 kph) during the second wave of an arctic storm that sent trees crashing onto houses, cars and roads. Forecasters expected the storm to dump as much as 10 feet (3 meters) of snow in the Sierra Nevada by Sunday. The heavy snow was slowing search efforts for a family believed to be missing in the mountains, authorities said. Highways from Sacramento to San Francisco were closed because of debris or toppled big rigs blocking lanes, and local roads were flooded. Interstate 80 was closed in the Sierra, the main link between Northern California and Nevada.