Professional Observation

Observation Details

Signs of Unstable Snow

Snow Stability

Key Points

Skinned out of Lee Vining Canyon today.

• Very firm snow surfaces as we left our car in the dark at 430 am. We were glad to have all our sharps with us.
• Overnight freeze at 8000′ in V-Bowl created surfaces that supported a skier on skis but stepping on the snow with a boot, I broke through 6 -8 cm frozen crust over unconsolidated MF grain clusters.
• Above 9000′ solid refreeze, no measurable boot pen at 8 am on a N aspect.
• By 900 am on a panel with a SE tilt half way up Coke Chute my boot pen was 30 cm. But as soon as the slope tilted more to the N or NE the boot pen was only a  a few cm’s.
• Skied from around 11300′ on a NE aspect at 1030 and had a great run in 2-4 cm of corn on a firm crust below. More textured snow in the bowl. N aspect above 9200 in the shade was still frozen and very firm at 1045. V- Bowl upper skiers right, to the right of the avalanche debris skied great with 10 cm of corn on a supportable crust. Below 8500′ the snow became too soft even on N aspects. Lower V-Bowl skied well on the raised up and smooth avalanche debris.
• Did not see any LW instability.
• Low to mid elevations are definitely deteriorating in stability even on northerly aspects.
• I can only imagine how much earlier and quicker the transition from very firm to too much, too deep loose wet snow happens on E-SE- S aspects. Especially on steep upper elevation solar aspects.
• Almost no detectable airflow in the upper chute. Very intense solar radiation.