North Cascades Highway is closed because of avalanche danger, according to the state Department of Transportation.
     "We have already had one slide today, and there are a couple dozen avalanche chutes between Diablo and Silver Star that are full and becoming more unstable by the hour as the temperature continues to climb," according to Jeff Adamson, spokesman for the DOT in Wenatchee.
     Highway gates are closed at milepost 134 on the west side and 170.6 on the east side.
     Avalanche experts are scheduled to return Monday, May 19, to assess avalanche and road conditions, Adamson said.
     "We will have a better idea then when we can reopen the highway," he said.
     The Northwest Avalanche and Weather Center has issued a backcountry avalanche warning advising everyone to stay out of the backcountry this weekend, according to the DOT.
     The North Cascades Highway, besides having more avalanche chutes than any other pass in the state, also has some of the tallest and longest chutes, according to the DOT.
     Avalanches could have the consistency of wet concrete and likely would include rocks and wood debris, "so you wouldn't want to be on the highway if that happens," said Adamson, who noted the situation is highly unusual.
     Traditionally, the highway's avalanche chutes aren't still full by this time of year.
     "This spring has been so cold that, while full, the chutes have remained stable," he said. "This 30-plus degree rise in temperature heats up the top layer of snow, making it heavier and creating a slip-plane with the layer below."
     If crews find significant slides on May 19, they could take several days to clean up, he said.
     More information is available on the DOT Web page, www.wsdot.wa.gov, or call 511.
     The highway opened for the season May 1.