The avalanche center in Idaho's Sun Valley area is urging people to consider cancelling their plans in the backcountry.
Snowmobiler George Gilbert Martin Jr., 64, died on Sunday when he was buried by an avalanche in the Sawtooth Mountains. Lesley Dianne Martin survived for 90 minutes under the snow before being rescued and transported to the hospital.
The Blaine County Sheriff's Department says the avalanche debris was up to 8 feet deep. Two other snowmobilers in the group, from Sutherlin, Ore., were able to extricate themselves from the snow.
Simon Trautman, director of the Sawtooth Avalanche Center in Ketchum, says recent snow storms have created a thick slab of snow – and it's not stable.
"Below that storm slab there's very weak old snow that is capable – you can think of it like a house of cards," Trautman says. "So it'll hold something, but if you somehow move some way or another the whole house will collapse."
Last week, two backcountry skiers died in an avalanche in Oregon's Wallowa Mountains. Nine people have died in avalanches across the West since Feb. 8.
The Northwest Avalanche Center in Seattle says the Cascade Mountains from Mount Hood to the Canadian border are at high risk for avalanches.