As layers of crisp orange and yellow leaves cover the sidewalks around Spokane, layers of snow are soon expected on several mountain passes, heralding the impending cold and wet La Niña.

Washington Pass on State Route 20 in the North Cascades is likely to see the heaviest snowfall in the coming days, the National Weather Service predicts. The service projected a 55% chance of 2 inches of snowfall on Sunday and a 100% chance of more than 2 inches on Monday, an 80% chance of more than 4 inches and a 50% chance of more than 6 inches . The snow poses a low risk to travelers, according to the service, which issued a winter weather advisory from Sunday evening through late Monday morning.

Other mountain passes could see snow, but the service predicts little to no snow-related risks to motorists.

At Stevens Pass, also in the Cascades on U.S. Highway 2, there is a 30% chance of more than 2 inches of snow falling on Monday, a 20% chance of more than 4 inches falling and a 15% chance that more than 6 inches fall.

For Wednesday and Thursday, the service is forecasting about 4 to 6 inches (10 to 15 cm) of snow accumulation, which will likely melt by the end of the week, meteorologist Valerie Thaler said.

“It’s not necessarily a pass closure event yet, the roads are still pretty warm,” Thaler said.

There is a slight 5% chance of more than 2 inches of snow falling on Route 20's Sherman Pass in northeast Washington on Monday.

There is a 1% chance of more than 2 inches of snow falling at Lookout Pass on Monday. However, the Idaho-Montana border is forecast to have a 20% chance of more than 2 inches of snow and a 5% chance of more than 4 inches.

The service forecasts no snowfall at Snoqualmie Pass in the coming days.

Thaler said the accumulation could lead to muddy and slippery roads on mountain passes earlier this week, but temperatures above freezing will likely prevent it from staying that way.

A cold and wet La Niña weather pattern is predicted for this year, but not quite there yet, Thaler said.

“After Wednesday and Thursday, things are looking pretty favorable and the chance of precipitation is pretty low,” Thaler said. “I’d say we’re just tiptoeing into winter.”