Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

On the final day of an AIARE Level 2 course, students planned and executed a tour that left Convict Lake, ascended Tobacco Flat, and descended Morrison Col back to the head of Convict Lake.

Lower moraines were a mixture of wind crusts and surface facets, though surfaces quickly changed by the time we reached Tobacco Flat. Winds have raked across all slopes, leaving sastrugi features, supportable and breakable wind board, and many elevated tracks from before the wind events. Our team opted to close Mono Jim E face and Old Man Bowl for both slide-for-life conditions and ski quality concerns. Treed terrain towards the ridge between McGee Mt. and Mount Aggie were not immune to the effects of strong winds.

We did not observe any of the forecasted winds in this drainage, with light ENE winds providing only some respite from the strong solar radiation. Morrison Col was mostly very firm and edgeable wind board, though isolated small wind slabs were observed (10cm deep, no larger than 3 meters in diameter). A skier in a separate group went for a long tumbling slide here when he lost an edge. Mostly variable conditions below the face, and a pleasant run down the final moraine in surface facets.