Tunnel Creek Backside Avalanche

While skiing at Tunnel Creek, we ventured to lookers right up the ridge above the hut. Hoping to ski the 'Backside (north facing)', from the high point of the ridge. As we started to descend skier #1 triggered a small slab (approx. 2x2 meters) on a convex roll showing evidence of a 20cm slab. Seeing this we decided to stay to denser trees. Shortly afterward, skier #1 took 3 turns on the edge of a clearing before venturing further into the opening, coming to a stop above a large tree. At this point skier #2 heard a whumpf and saw the crack propagating across the opening 20m above skier #1. The avalanche occurred in an open area 20 meters wide, at about 38+ degrees. Skier #1 was stopped above the tree and anchored themself to it, bracing for the avalanche. The snow swept around the tree and continued down the slope. Skier #1 remained safely anchored throughout the avalanche. The initial plan to exit the terrain was to ski the bed surface, where we found steeper unskiable terrain. Left with few safe options we climbed an adjacent pathway through the dense trees until the slope angle was manageable.