New snow and wind are expected to form reactive storm slabs on Monday.
If you see less than 10 cm of new snow, the danger may only be MODERATE.
Storm slabs will be forming throughout Monday, with 10 to 15 cm of snow accompanied by moderate to strong southwest winds. These slabs will be especially reactive in wind loaded areas or where they overlie buried surface hoar.
A crust with weak facets and/or depth hoar exists at the base of the snowpack in many areas. This layer is most likely to be triggered in thin snowpack areas less than a meter deep, or with very heavy loads.
On Saturday
A few small wind slabs were ski cut at treeline and below treeline elevations. They failed on a buried layer of surface hoar.
A large (Size 2) naturally-triggered wind slab failed on a north-facing alpine slope.
On Friday
Two size 1-1.5 storm slabs were reported in this MIN post, and a small wind slab ski cut was reported in this MIN post.
Looking forward
We expect storm slabs to become more reactive as snow accumulates on Monday.
10 to 20 cm of new snow on Monday, combined with strong southwesterly winds, will build fresh storm slabs. These slabs are expected to be most reactive in wind-loaded areas
Around 30 to 40 cm of snow currently overlies surface hoar in wind-sheltered terrain, and a sun crust on steep south-facing slopes. The new snow may overload these layers, creating larger-than-expected storm slabs.
A deep persistent weak layer consisting of a thick melt-freeze crust, with weak faceted snow and/or depth hoar, can be found near the ground.
Sunday Night
Cloudy. 0 to 5 cm of snow. 30 km/h southwest ridgetop wind. Treeline temperature -4 °C. Freezing level around 1300 m.
Monday
Cloudy. 5 to 15 cm of snow. 40 km/h southwest ridgetop wind. Treeline temperature -3 °C. Freezing level around 1500 m.
Tuesday
Mostly cloudy. 3 to 5 mm of precipitation as snow or rain at treeline. 25 km/h west ridgetop wind. Treeline temperature 1 °C. Freezing level around 2500 m.
Wednesday
Mostly sunny. 30 km/h west ridgetop wind. Treeline temperature 3 °C. Freezing level around 3000 m.
More details can be found in the Mountain Weather Forecast.
