Triggering storm slab avalanches remains likely as another frontal system will bring new snow and cooler temperatures on Tuesday.
New snow will continue to add to storm slabs at higher elevations on Tuesday. Expect the depth and reactivity of slabs to greatly increase with elevation and exposure to wind.
MONDAY NIGHT: Light snow with up to 5 cm above 1500 m, strong wind from the south, alpine temperatures drop to -3 C.
TUESDAY: Cloudy with increasing snowfall bringing 10-25 cm of new snow, increasing with elevation and proximity to the coast, strong wind from the south, alpine high temperatures around -5 C with freezing level dropping to 1200 m.
WEDNESDAY: Cloudy with isolated flurries, light wind from the south, alpine high temperatures around -5 C.
THURSDAY: Heavy snow with 30-50 cm of snow above 1800 m and heavy rain below, strong wind from the south, alpine high temperatures around -1 C.
Numerous small (size 1) slab avalanches were triggered by riders on Sunday, while larger (size 2) wind slab avalanches were triggered naturally and with explosives. Looking forward, continuing snowfall is expected to maintain similar conditions on Tuesday, with new snow and associated avalanche hazards increasing with elevation.
A frontal system crossing the region on Tuesday will start with rain and transition to wet snow by the afternoon. 10-25 cm of new snow will accumulated above 1000 m. A pair of weak surface hoar layers from mid and late December existed about 70 to 160 cm below the surface in advance of the storm. These layers were given a good loading test at most elevations by the storm, but still warrant caution around steep, sheltered slopes and shallow rocky areas. A layer of sugary faceted grains and hard melt-freeze crust exists near the base of the snowpack in inland parts of the region, such as the Spearhead Range. This layer also received a good loading test by the storm, but continues to warrant avoidance of shallow rocky start zones in the alpine and upper treeline.
