Major Evans avalanche. Probable soft slab, South West facing, starting around 10,700ft. Steepness unknown, depth estimated at 18-30inches. Width estimated at 250ft. Vertical around 500ft. Weak layer possibly sun crust, trigger possible snowmobile (a single track was observed coming out of the toe.) Avalanche was possibly a few days old on the 11th. In addition, a small 10ft wide, 1ft deep crossloaded windpocket was triggered from about 75 below on the climb up North East facing Mary Ellen at about 9900ft. Suspect cross loading from Saturday the 6ths unforecasted strong South East winds.