Microwave-Sinclair

Triggering avalanches is possible on alpine slopes due to wind slabs and a buried weak layer.

No avalanches have been reported since Tuesday.

On Monday the field team observed a recent large windslab that stepped down to weaker layers buried in the snow. See the report here.

On Sunday a rider triggered a large (size 2.5) slab avalanche on a southeast alpine slope. The slab ranged from 20 to 100 cm deep with wind loading variability. The slab may have released on the persistent weak layer described in the Snowpack Summary.

5 - 10 cm of new snow is now above previous highly variable surfaces. Strong winds continue forming pockets of wind slabs. Crusts have been reported on south-facing slopes, and surface hoar has been observed at lower elevations.

A weak layer of facets and crust from early December is buried approximately 50 to 100 cm deep. This layer likely contributed to avalanches last weekend but should be less reactive under current conditions, primarily posing a concern on steep rocky slopes.

Thursday Night

Mostly cloudy with up to 5 cm of snow. 30 to 40 km/h south ridgetop wind. Treeline temperature -12 °C.

Friday

Mostly cloudy with 5 to 10 cm of snow. 30 to 50 km/h southeast ridgetop wind. Treeline temperature -12 °C.

Saturday

Mix of sun and cloud with flurries. 20 to 40 km/h northeast ridgetop wind. Treeline temperature -20 °C.

Sunday

Mostly sunny. 40 km/h northeast ridgetop wind. Treeline temperature -20 °C.

More details can be found in the Mountain Weather Forecast.

• Avoid steep, rocky, and wind-affected areas where triggering slabs is more likely.
• Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
• Watch for signs of instability like whumpfing, hollow sounds, shooting cracks, or recent avalanches.