Tire chains. Winter coats. Gloves. Remember them? Snow is expected to fall across the Sierra Nevada early next week as a storm from the Gulf of Alaska pushes into California and the rest of the West Coast, bringing a likelihood of light rain to the Bay Area. Although details will become clearer in the next few days, forecasters said Friday that at least a foot of snow is expected to fall at higher elevations on Tuesday in the Sierra, potentially causing visibility issues and the need for motorists to carry tire chains if they are heading over mountain passes Tuesday and Wednesday as temperatures fall.