The second major storm in two days washed across Northern California on Sunday, prolonging the threat of flooding as residents tried to clean up thick layers of mud and debris left behind as the first wave of floodwater receded. Hundreds of homes and businesses were inundated on Saturday as heavy rain sent the Napa and Russian rivers spilling over their banks. At least 2 more inches (5 more centimeters) of rain was forecast across Northern California on Sunday, on top of the 4 to 9 inches (10 to 23 centimeters) that had already swamped the region, the National Weather Service said. Officials were urging residents who had left to stay out for another day, and those who hadn't, to evacuate. About 50 people were in emergency shelters, said Linda Eubanks of Sonoma County's Office of Emergency Services. The storm moved into the Rocky Mountains on Sunday as a blizzard, making rescue efforts challenging after an avalanche near Rocky Mountain National Park that killed two snowmobilers. At least one death in California was blamed on the storm, a man killed by a falling tree in Vacaville, authorities said.