The avalanche that killed a snowmobiler in the Lost Johnny Basin west of Hungry Horse Reservoir on Monday was moderate in size but powerful enough that the victim apparently died of trauma.

That assessment comes from Forest Service avalanche expert Stan Bones, who visited the site Tuesday.

The late afternoon avalanche claimed the life of Charles John Dundon III of Connell, Wash., while a companion snowmobiler was able to escape harm.

Bones happened to be in the Lost Johnny Basin on Monday afternoon assessing avalanche conditions.

“We saw those two fellows leaving the parking lot late in the afternoon,” said Bones, who found “signs of instability” in the snow during his field survey that day.

The two snowmobilers were caught in “very moderate terrain” for avalanche danger, Bones said.

“It really was not a major avalanche,” he said. “It was a moderate-sized avalanche.”

The two were riding across the slope just above a road when the avalanche was triggered. Bones said the slide “reached up” the slope, gathering more snow from above and creating most of the force that hit the snowmobilers.

“Once it released there was a lot of snow moving above them,” Bones said. The slide was about 250 feet wide and about 500 feet long, and the two riders were caught at about the bottom third of the avalanche’s run.

The victim’s helmet and backpack were torn off, indicating there was considerable force. He was swept into a cluster of three trees and when his body was recovered later that night under about five feet of snow, the snowmobile was upside down and on top of his legs.

The trees or the snowmobile likely caused the fatal trauma, Bones said.

Bones noted that Dundon was wearing a transceiver beacon, but his partner did not have one to use to locate Dundon’s signal. Search and rescue responders were able to quickly locate the signal, but because of the nature of Dundon’s trauma, Bones said it’s unlikely that the outcome would have been different if Dundon’s partner had a beacon.

The slide partially buried Dundon’s partner, but he was able to extricate himself and return to Hungry Horse and call for help.

Bones said the Glacier Country Avalanche Center will issue a detailed report on the incident in the near future.

Reporter Jim Mann may be reached at 758-4407 or by email at jmann@dailyinterlake.com.