A strong, wind-packed spring storm has the potential to flood a river in the Sierra Nevada and soak the San Francisco Bay Area, forecasters said. National Weather Service forecaster Idamis Del Valle said the storm will reach the area late Thursday and the heaviest rain is expected on Friday. The region could see more rain on Saturday, Del Valle said. The Feather River could flood the Sierra Nevada town of Portola, which is near the Nevada state line, the National Oceanic and Atmospheric Administration said.