A warm, wet storm is creating dangerous avalanche conditions. Avoid avalanche terrain.
Several persistent weak layers exist in the upper metre of the snowpack. Small avalanches in motion may trigger these deeper layers creating large and destructive avalanches.
Another 10 to 20 cm of new snow will add to the existing storm storm slab problem. Wind-loaded slopes will be especially dangerous.
Storm slabs have produced many size 1 to 2 avalanches in recent days, including numerous human-triggered slabs in the top 30 cm and larger natural avalanches in alpine terrain.
Large natural and artificially triggered persistent slab avalanches to size 3 were reported most recently on Saturday.
Expect continued storm slab activity on Monday. Persistent slab avalanches will become increasingly likely as temperatures warm this week.
Continued snowfall over the day Monday will bring storm totals into the range of 50 to 70 cm.
Several weak layers in the snowpack are currently concerns for triggering persistent slab avalanches:
Facets/surface hoar/crust from early March buried 50 to 80 cm deep,
Facets/surface hoar/crust from mid-February buried 70 to 100 cm deep, and
Facets/surface hoar/crust from late January buried 100 to 150+ cm deep.
This complex snowpack combined with dynamic weather makes travel in avalanche terrain dangerous.
Sunday night
15 to 30 cm of snow, turning to rain below 1600 m. 40 km/h southwest ridgetop wind. Treeline temperature 0 °C. Freezing level rising to 2000 m.
Monday
10 to 20 cm of snow, rain below 1500 m. 30 to 40 km/h southwest ridgetop winds. Treeline temperature +2 °C. Freezing level 2000 m, rising to 2400 m.
Tuesday
5 to 10 mm of rain overnight then clearing skies in the afternoon. 20 km/h southwest ridgetop wind. Treeline temperature +6 °C. Freezing level 2700 m.
Wednesday
Sunny. 20 to 30 km/h southeast ridgetop wind. Treeline temperature +10 °C. Freezing level 3200 m.
More details can be found in the Mountain Weather Forecast.
