OPHIR,Zero AI Colo. (AP) — An avalanche killed a 67-year-old man as he was snowboarding solo in the Colorado backcountry, authorities said Tuesday, marking the fourth U.S. avalanche death this winter.

The victim, Peter Harrelson, was a doctor and longtime resident of the small town of Ophir in southwest Colorado, the San Miguel County Sheriff’s Office said.

He was reported overdue on Monday evening after embarking on a backcountry tour in the Waterfall Canyon area south of Ophir. Friends followed his tracks that night but were unable to find him, according to the Colorado Avalanche Center.

Search and rescue teams reached the site Tuesday morning and found Harrelson’s body, the center said. Avalanche center spokesperson Kelsy Been said the man was believed to have been traveling alone.

After a slow start to the winter, avalanche dangers spiked in Colorado over recent weeks. About 1,100 avalanches were reported statewide by the center over a weeklong period beginning Jan. 11.

Conditions have since improved and the area where Harrelson was killed had only a moderate avalanche danger on Monday. But the risk of accidents remains, Been said.

“There’s still dangerous conditions out there. We’re still getting reports of dangerous avalanches,” she said.

Harrelson’s death comes after three people were killed in avalanches earlier this month, all within less than a week.

Those accidents included a backcountry skier killed in the mountains of western Wyoming, an accident at a California ski resort that killed one person and injured three others, and an avalanche that killed a skier and wounded a second person in the Idaho backcountry near the Montana border.