The Chugach National Forest Avalanche Information Center was predicting dangerous avalanche conditions at upper elevations in the Turnagain-area backcountry Sunday, and advising against travel in avalanche terrain.
In an advisory issued Sunday morning, the avalanche information center said the avalanche danger would be "high" for elevations above 2,500 feet for the first time this season. For elevations between 1,000 and 2,500 feet, the danger was listed at "considerable." The advisory applies to backcountry along Turnagain Arm, "with Turnagain Pass as the core advisory area."
A warm, intense storm rolling in from the south is bringing strong winds and between 10 and 16 inches of new snow at higher elevations, according to the advisory and the National Weather Service.
There was no avalanche danger at elevations of 1,000 feet or lower, but forecasters were recommending that travelers avoid all avalanche terrain Sunday and Monday.
"(S)teering clear of the bottom of avalanche path runout zones where debris from above could gain enough momentum and be funneled into this snow free zone is advised," Wendy Wagner, director and avalanche forecaster at the Chugach National Forest Avalanche Information Center, wrote in Sunday's advisory. "For example, avoiding hiking along trails in the Portage Valley."
In an interview, Wagner said rain is currently falling at the tree line, which will likely keep people away.
"Today looks to be a good day for Christmas shopping," she wrote in the advisory.
Over the last four clear, cold days, feathery frost patterns have formed over the snowpack, Wagner said. But the layer of frost can keep new snow from bonding with old snow, becoming a "persistent avalanche problem," Wagner said.
"That's our big red flag going into the future," Wagner said. She said it's not clear if that will happen with the current storm, but forecasters will be following the evolution of the snowpack "very closely," as conditions become more complex. She said people should be vigilant about checking conditions before traveling or recreating.
Wagner said the information center will put out an update on its website on Monday if conditions change dramatically. The center's next scheduled forecast is for Tuesday.
Check avalanche forecasts and weather conditions at http://www.cnfaic.org.