Avalanche danger will increase through the day as storm slabs build.
For alpine and treeline elevations, HIGH danger will apply when more than 30 cm of new snow has fallen.
As temperatures trend milder, the new snow will take on more soft slab character than the unconsolidated fluff we were seeing in previous days. Expect reactive storm slabs to build through the day. Watch for wind loaded pockets in lee features in the alpine.
Wednesday night: Increasing cloud. There is uncertainty as to the timing of the arrival of the heavy snowfall. There is a chance of up to 20 cm overnight. Moderate south to southwest winds. Alpine low around -18 C.
Thursday: 10-20 cm of new snow through the day. Moderate southwest winds easing to light. Alpine high around -10 C.
Friday: Up to 15 cm of new snow overnight then a mix of sun and cloud with isolated flurries. Light to moderate southwest winds. Alpine high around -8 C.
Saturday: Mix of sun and cloud with scattered flurries bringing 5-10 cm of new snow. Light to moderate southwest winds. Alpine high around -6 C.
Reports since Monday consist of explosive and skier controlled storm slab avalanches mostly around size 1.5, as well as small (size 1) natural and skier triggered loose dry in steep terrain. These MIN reports from Sunday describe natural storm slab avalanche activity including a cornice triggered size 2 storm slab.
Looking forward, as temperatures trend milder with a continuing supply of new snow and moderate winds, reinvigorated storm slab activity is expected.
As temperatures trend milder, 20-40 cm of new snow will take on more soft slab character than the unconsolidated fluff we were seeing in previous days. In the alpine, the new snow rests on wind affected surfaces. Expect freshly wind loaded pockets in lee features and continued cornice growth.
Several crust layers exist in the mid snowpack as a result of previous warming and rain events. These have not been identified as bed surfaces or failure planes in recent avalanche activity.
The bottom 10-20 cm of the snowpack consists of faceted snow and decomposing crusts. Although inherently weak, this basal layer has not been an active avalanche problem in our region for several weeks.
