New snow and variable winds will continue to build wind slabs in open terrain features. Seek out sheltered areas to avoid the hazard and enjoy softer snow.
Strong to extreme southwest winds have transported 20-40 cm of recent storm snow, scouring windward slopes and loading leeward features with thick wind slabs. Approach all lee and cross-loaded terrain with caution.
Keep in mind that larger wind slab releases have the potential to step down to the weak basal snowpack, resulting in very large and consequential avalanches.
A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and alpine elevations. Riders are most likely to trigger an avalanche on this layer in steep terrain where the snowpack is, shallow. Your best defence is to stay diligent in choosing low-consequence terrain away from overhead exposure.
A helpful MIN report from Saturday in Perry Creek describes active wind slab formation conditions and a solid avoidance strategy. We suspect users who start poking into higher elevations will see evidence of a natural wind slab avalanche cycle.
Looking forward, wind slabs formed by the recent stormy weather are expected to remain reactive to human triggering over the near term.
A few more centimeters of new snow adds to the continued development of wind slabs in lee terrain features in wind-exposed areas by strong to extreme southwest winds. These new wind slabs are building over older wind slabs that may be lingering at treeline and alpine elevations as well as a melt-freeze crust found on sun-exposed slopes and all aspects below 1600m.
Several more crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. The most concerning persistent weak layer is at the base of the snowpack, composed of large and weak facets formed in November. This layer is widespread and most likely triggerable in steep, rocky alpine terrain.
In general, the snowpack is weaker and shallower in this area than in areas farther west, with an average snowpack depth of around 200 cm at treeline. This makes deep persistent slab problems in thinner snowpack areas here quite a bit more concerning.
Monday night
Mainly cloudy with convective flurries, 5 to 7 cm accumulation. 20 to 30 km/h southwest winds increasing into the evening, treeline temperatures -10° C dropping overnight.
Tuesday
Cloudy. trace accumulations, 20 km/h northwest winds increasing overnight and switching to the southwest, treeline temperatures -13 °C.
Wednesday
Becoming cloudy, 40 to 50 km/h southwest winds, treeline temperatures around -8 °C.
Thursday
Mix of sun and cloud, 50 to 60 km/h southwest winds, treeline temperatures around -8 °C
More details can be found in the Mountain Weather Forecast.
