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North Cascades Highway Closes For Season; Avalanche Chutes Filling With Snow

Washington State Department of Transportation


The North Cascades Highway closed for the season late this afternoon for driver safety.

Over the weekend, two of the four Liberty Bell Mountain avalanche chutes — which are natural channels down the sides of mountains — filled and released snow onto to the shoulder of the the North Cascades Highway.


"Those avalanche chutes are about 2,000 feet high, which is far larger than any of the other avalanche chutes on the other passes," Washington State Department of Transportation spokesperson Jeff Adamson said. "So even just a couple of inches of snow, when it slides that full distance can cover the highway in an instant."


The 37-mile stretch of State Route 20 between Diablo and Mazama has 27 avalanche chutes total and closes each winter.


"We can’t put our maintenance crews up there at risk of having those snow slides come down on top of them, much less the traveling public," Adamson said.


Later in the winter, the closure will expand another 4 miles west to milepost 130 and 7 miles east to milepost 178.


Adamson said alternate routes have no problem handling the extra traffic, because the North Cascades Highway doesn’t typically have a high volume of travelers.


It will reopen in the spring when snow stops falling and WSDOT crews can clear the road. This usually happens in early May after conditions are assessed early in the spring. As much as 50 feet of snow can accumulate on the road by then.

The area will still be open for recreation like snowshoeing, cross-country skiing and snowmobiling. Parking will be available near the closed gates.


Adamson said avalanche crews are predicting an average winter in the North Cascades.

Credit Washington State Department of Transportation
A map of avalanche chutes on the North Cascades Highway.