Avalanche Forecast
Regions: Lizard-Flathead.
There is uncertainty about the potential for triggering large avalanches on buried weak layers. This uncertainty is best managed with conservative terrain choices.
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
MONDAY NIGHT: Mostly cloudy, 30 km/h wind from the west, alpine temperatures drop to -10 C.
TUESDAY: Mix of sun and cloud, 20-30 km/h wind from the west, alpine high temperatures around -6 C.
WEDNESDAY: Mix of sun and cloud, 30-50 km/h wind from the northwest, alpine high temperatures around -4 C.
THURSDAY: Scattered flurries with 5-15 cm of new snow, 40-60 km/h wind from the west, alpine high temperatures around -2 C.
Avalanche Summary
Numerous storm slab and persistent slab avalanches were reported over the weekend. Explosive control in the Lizard Range produced numerous large slab avalanches (size 2-3) at treeline and alpine elevations. The avalanches ran on the both the November and October crust layers 40-100 cm deep. Smaller skier triggered slabs (size 1) were also reported over the weeknd, including this MIN report from Harvey Pass on Saturday. While avalanche activity likely peaked during the storm, triggering storm slab and persistent slab avalanches remains a concern as the snowpack adjusts to the weight of the new snow.
Snowpack Summary
30-40 cm of fresh snow is settling into a storm slab and being blown around by wind at upper elevations. Crust layers from November and October can be found 40-100 cm below the surface and have recently produced large avalanches with explosive triggers. While these layers are likely widespread across the terrain, we are uncertain about whether they could also be triggered by humans. Snowpack depths range between 50-100 cm at higher elevations and taper rapidly below treeline.
Avalanche Problems
Storm Slabs
30-40 cm of recent snow has formed slabs that could be triggered in steep and wind affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
There is uncertainty about how easy (or difficult) it could be to trigger a large avalanche on one of the crusts and weak layers in the lower snowpack. Choosing conservative terrain is the best way to manage this uncertainty.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3