A father and his son are dead after their snowmobile group was caught in an avalanche on Mount Brewer in the Purcell Mountains, near the community of Invermere, B.C.

A total of nine snowmobilers from Calgary were near the southeast side of Mount Brewer on Saturday. The slide was between 200 and 400 metres wide and ran onto a small lake.

Columbia Valley Search and Rescue responded and found 51-year-old Larry Burdiga from Calgary under two metres of snow. He was flown to hospital in Invermere, where he was confirmed dead.

B.C. RCMP said they recovered the body of 24-year-old Matt Burdiga who was believed to have been caught in the avalanche and swept into the lake near Mount Brewer.

A preliminary release from Avalanche Canada said rescuers picked up a transceiver signal on the lake where the avalanche ended. The agency also said Larry Burdiga had activated his avalanche airbag, but it didn't stop him from being buried.

The RCMP's Underwater Recovery Team searched the area on Sunday without success. The team was sent to the scene again on Monday.

RCMP said the other seven snowmobilers in the group were unhurt. Cpl. Dan Moskaluk said the avalanche may have been triggered after one of the snowmobilers was highmarking — an activity where a snowmobiler tries to ride as far as possible up a steep hill, then turn and come back down without rolling or stalling.

A helicopter lands near the site of the avalanche on Mount Brewer. (Avalanche Canada)

Skier killed farther west

The snowmobilers' deaths are the second and third avalanche deaths in B.C. in the last two weeks.

Earlier this month, a 42-year-old skier was killed in an avalanche in the backcountry near Pemberton. Friends found him after he was buried in the area near Pebble Creek on Jan. 3, but he couldn't be revived.

The avalanche danger rating in the area was "extreme" at the time.

Columbia Valley Search and Rescue found one of the snowmobilers buried under two metres of snow with his avalanche airbag activated. The 51-year-old Calgary man was pronounced dead in hospital. (RCMP)

The Purcells have been seeing poor conditions since the fall, according to Avalanche Canada.

"The conditions in the Purcells, in particular, have been problematic for quite a while now," said Karl Klassen, warning service manager for the Revelstoke-based agency.

"We suspect the layer that is creating the larger avalanches in this region formed in October. It's been a problem ever since then, but it's come alive lately as we've had more snow pile up on that layer."

Klassen said that weak snowpack combined with a recent clear, warm spell has created a dangerously delicate environment.

"It's very sensitive to triggering in the Purcells right now," he said. "The danger ratings in the Purcells have been elevated for the last several days at least."

Saturday's avalanche bulletin for the Purcells warned that warm air and sunshine could make slides "more likely" and cautioned backcountry users to avoid alpine terrain entirely.

On Monday, an updated bulletin said "people have recently triggered large avalanches within the weak Purcells snowpack."

An annual report from Avalanche Canada said there were 102 avalanche-related deaths in B.C. between 2009 and 2018.