Surprise Valley

On February 7th at 1430h, 3 skiers were caught in a sz 2 avalanche in the Surprise Valley area near Medicine Lake. The avalanche occurred at 1950m on a West aspect estimated slope angle of 30 deg. The group was in the process of skinning up through a section of open mature trees. The first member of the crew proceeded out into an open glade and produced a whumpf with cracking in a 5m radius. The slope slumped and paused before further releasing ~20m above, failing on ground and propagating 25m wide. The slab involved the two other skiers in the party and traveled 80-100m down slope. When the slide came to rest 2 members of the party were on the surface with one member buried with only the sole of a boot exposed. The buried member was quickly located with a transceiver search and extricated. No members of the party suffered injury. One ski and one pole were lost in the slide. The group made their way back to the Maligne Lake Road without incident. Bed surface was ground/basal depth hoar and the failure occurred in this basal instability. The depth of the crown was estimated at 70cm. While skinning up the team observed 30-40cm HST sitting on depth hoar to ground. HS 60-100cm. There were no whumpfs or cracking, and no slab observed in the HST. From the road on the drive up one sz 3 Na was observed in the alpine on a similar aspect from the last storm cycle but there was no other evidence of natural activity.