Avalanche chutes fill up, SR 20 North Cascades Highway closed for the season

SR 20 Avalanche areas North Cascades Highway
WSDOT

Scenic mountain highway closed at mileposts 134 and 171 on Nov. 28

DIABLO – Get the holiday decorations ready – the snowy season has arrived, at least in the mountains. Enough snow has fallen in the North Cascades that avalanche chutes are full and, for traveler safety, the 37-mile seasonal stretch of State Route 20 will closed Wednesday, Nov. 28.

The Washington State Department of Transportation will swing the North Cascade Highway gates closed at milepost 134 near Diablo and milepost 171 near Mazama. This section will remain closed until sometime in 2019 when the snow stops falling and melts enough to make it safe for maintenance crews to plow the road.

Winter access
Snowshoers, cross-country skiers, fat-tire bikers or snowmobilers can access the closed area throughout the winter. Parking is available near each closed gate. Anyone choosing to use the area should know the conditions, including avalanche risks, watch the forecast and bring proper gear.

Later this winter, once there is significant snowfall, adventurers should plan for the gate closures to expand on both ends of the North Cascades Highway. In the Diablo area it will move back to milepost 130, on or after Jan. 2, 2019. The closure in Mazama will move back to milepost 178 once snow is too deep for snow blowers. Extending the closure area when the snow gets heavier and deeper saves money and resources. There will still be parking available at both closure locations.

Highway history
WSDOT opened the final section of SR 20/North Cascades Highway in 1972. Each year crews close it to vehicles for the winter due to the snow in the 27 avalanche chutes that loom above the highway. That closure usually happens in November or December. However, in previous years the highway has closed as early as October. The latest closing was Jan 3, 1990 and in 1976-77 the highway remained open all winter due to the lack of snow.

Spring 2019 reopening
Avalanche experts will assess conditions in the spring. When it is safe, WSDOT will move snow blowers, plows and loaders to the area to start clearing snow, removing winter debris and replacing damaged guardrail and signs. That clearing process usually takes about eight weeks.