Keystone Standard Basin

Snowmobiling group of 5. Large class 2 Avalanche, remotely triggered from 250m below with 30-36” convex crown and a secondary step down 2/3 of the way down slope. No other avalanche indications / activity noted for remainder of day. Northeast Facing. 35 degrees plus at edge of convex. Rider was less than 5’ away of run out and had the slide go less than 1 second behind him. Rider did not see until 2 seconds before as it passed immediately behind. About 10’-15’ deep debris field in bottom of bowl. Actual location- 51°26'01"N 118°20'42"W