SAN FRANCISCO — Light showers fell on parts of Northern California bracing for heavy rain and strong winds Wednesday that could unleash mudslides on communities struggling after the deadliest U.S. wildfire in a century. Water levels could rise in small rivers and creeks and debris flows could hit areas scarred by flames, including where a November wildfire killed 86 people and destroyed nearly 15,000 homes. A week of storms has left authorities concerned about the potential danger for thousands of people living in foothill and canyon areas devastated by last year’s wildfires.