Unstable wind slabs on Andesite Peak

Wind slabs were easy to trigger (reactive) in the textbook locations below cornice features in near treeline to above treeline locations. Close approach to within a couple of feet of the slab edge was required to trigger. Once in close, wind slabs up to 2 feet deep were easy to trigger with the weight of a skier or intentionally collapsed cornice pieces of about 0.5 cubic meters. Wind slabs were 4F hard with the storm snow weak layer at F hard. 4F hard storm snow bed surface.

Significant amounts of storm snow existed in ridgetop locations, ready for transport by the next wind event.

In wind protected areas below treeline, storm slab instability was minimal and limited to the top 10 cm (4 in) of the storm snow. Cracking triggered while breaking trail did not exceed 2 feet in length and stayed close to the skin track edge. Test slopes below treeline either failed as narrow, shallow loose dry or did not fail at all.

A test pit dug at the noted lat/long (ENE aspect, 8,100', above treeline terrain) revealed 1.75 m (5.75 ft) of recent storm snow with the lower storm snow 4F to 4F+ hardness. This location is lightly wind loaded by SW winds and had an HS of 4.75 m (15.6 ft). Tests targeting the non persistent weak layers within the storm snow that contributed to avalanche activity in this area yesterday were unreactive today. CTH results in the mid and lower portions of the storm snow both had broken failure planes. ECT on these failure planes produced ECTN on the upper failure plane and ECTX on the lower failure plane.

Convective snow showers and 100% cloud cover for most all of the hours while in the area from 9 am to 2 pm. Snowfall rates ranged from S1 to S5. Only a couple sun breaks of 5 min or so occurred.