The primary avalanche threat remains persistent slab. In steep, high-elevation, wind-affected terrain that held snow from early October, skiers and rider could trigger slab avalanches one to three feet deep. These slabs have the potential to kill or seriously harm backcountry travelers. To avoid this threat, determine if the October rain crust and faceted snow combination is present, and assess the slab properties of the overlying snowpack. Collapsing and shooting cracks are an obvious clue that a sufficient slab exists for propagation of an avalanche. In terrain where the crust/facet combination is absent, avalanche activity is unlikely.
The combination of weak, faceted snow lying on a strong rain crust primarily exists on westerly through northerly to easterly aspects above 9,000 feet. In mostly shaded terrain, this sliding surface and weak layer combination dips below 9,000 feet. Backcountry travelers could trigger slabs failing on this layer to depths up to three feet in steep, wind-affected terrain.
Expect increasing cloud cover overnight and into Saturday as the first in a series of fast moving Pacific weather systems hits the region late in the day on Saturday. Overnight lows in the mountains will dip into the single digits before rising into the mid teens during the day. Westerly ridgetop winds will increase to 15 to 25 miles per hour.The general avalanche hazard is expected to remain MODERATE on Saturday with persistent slabs continuing to be the primary avalanche problem of concern. Two ingredients are necessary to be exposed to this threat. First, faceted snow above the October rain crust needs to be present to provide a weak layer and a bed surface. This combination primarily exists on westerly through northerly to easterly aspects above 9,000 feet and dips below 9,000 feet in mostly shaded terrain. Second, there needs to be a strong enough slab to propagate failure of the faceted snow. Skiers and riders could trigger these slabs to depths of one to three feet. In terrain where the facet/crust combination is absent, avalanche activity is unlikely.
