Mammoth Crest

We headed up to the Ship's Prow area to investigate the slab avalanche reported recently by another forecaster. 

• The avalanche failed on weak facets sandwiched between stiff wind-deposited layers.
• The overlying slab developed as a result of east wind cross-loading the start zone around 12/21.
• The slab broke down to another weak layer of facets. The bed surface was snow left over from last winter.

It was challenging to travel near and above treeline with the snowpack so thin and obstacles everywhere. We traveled on scoured surfaces, or on the debris and bed surface of a slope that had already slid to avoid the avalanche problem that exists where wind-drifted snow overlays old weak facets. Unfortunately, those are the areas that currently have the most snow. We moved carefully to avoid injury and very little of what we did could be called actual skiing.

Localized cracking where previous east wind had stiffened the snow over weak facets near and above treeline. The snow adjacent to the avalanche we investigated (the "hangfire") was still sensitive and we got long shooting cracks stepping on it.

The snowpack is thin, faceted, and weak. Cold northerly slopes near and above treeline are faceting at the surface. Surface hoar is widespread in areas sheltered from the wind and sun.

The snowpack in alpine terrain is a complex mix of stiff wind-packed layers and sugary facets. Some areas are scoured down to just a few inches over grass and rocks while others have drifted snow over weak layers and crack around you. 

Warm temperatures caused slopes that face the sun near and below treeline, and slopes under tree cover, to form a thin melt-freeze crust late in the afternoon. Steep solar slopes are mostly snow free and we did not see any wet loose avalanches despite sun and warm temps.