Mar. 1—A snowmobiler was killed by an avalanche Saturday near North Idaho's Tiger Peak.
Four snowmobilers were riding on the 6,404-foot Custer Peak, which is southwest of Tiger Peak, when an avalanche buried two of them, according to Avalanche.org. One rider was fully buried and died on scene. He was recovered by search and rescue crews Saturday night. The other rider was partially buried and rescued.
The area is about 10 miles northwest of Wallace, Idaho.
The avalanche occurred on a 34-degree-slope leading directly into trees, said Jeff Thompson, the director of the Idaho Panhandle Avalanche Center. Thompson and other forecasters from the nonprofit avalanche forecasting center investigated the scene Sunday.
"It kind of looked liked it was triggered on a highmark," he said. "The fractured line kind of followed a snowmobile track. We thought that might be where it failed."
Highmarking is when a snowmobile rider drives up a steep mountain slope and then turns and races down.
The avalanche crown, which is where the snow fractures and breaks away from the rest of the snowpack, was nearly four feet deep, Thompson said. The avalanche traveled about 1,000 feet and ran into the trees downslope, Thompson said.
The Shoshone County Sheriff's Office responded to the incident around 4 p.m. Saturday and recovered the body around 7 p.m.
The deceased snowmobiler was Ron Sink, according to The Shoshone-News Press.
The Panhandle Avalanche Center's conditions report for Friday judged the avalanche danger for the Silver Valley region to be considerable.
"Our buried persistent weak layer is now in the deep category," according to the forecast. "It will be harder to trigger, but the consequences will be much bigger if it does go. Storm slabs or wind slabs that are triggered higher in the pack have the ability to step down to create a much bigger avalanche. The snow is nice and light and fluffy, so have fun playing it safe on conservative terrain."
After investigating Sunday, Thompson said this is is what appears to have happened. The snowpack broke on a layer of surface hoar that formed on Feb. 6. Surface hoar is much like the morning frost on a windshield and is slippery and doesn't bond well with the snow above.
Thompson urged backcountry recreationists to be conservative.
"This hasn't gone away yet," he said of the persistent weak layer from Feb. 6.
It's been an unusually deadly avalanche season in the United States. Thirty-three people have died in avalanches in the United States so far during the 2020-21 season. That's partly due to a tricky and unstable snowpack throughout much of the western U.S. and increased winter backcountry recreation, which some experts have attributed to the COVID-19 pandemic.
The Panhandle Avalanche Center will release more information on the accident later this week.
"Our condolences go out to family and friends affected by the avalanche on Tiger Peak in the Silver Valley today," IPAC posted Saturday on Facebook. "The Avalanche Center is currently looking into the details of the incident."
This story will be updated as more information becomes available.