Watch for reactive wind slabs as you transition into wind-affected terrain. Avoid shallow, rocky areas where the snowpack transitions from thick to thin, and human-triggering slabs is more likely.
+20 cm of storm snow and southwest winds are building fresh wind slabs in treeline and alpine lees. Approach lee and cross-loaded terrain with caution.
Keep in mind that wind slabs have the potential to step down to deeper weak layers, resulting in 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, shallow terrain. Your best defence is to stay diligent in choosing low-consequence terrain away from overhead exposure. See more on the potential of triggering deeper weak layers in our latest Forecasters' Blog.
No new avalanches have been reported, but field information is very limited in this region.
We suspect users who head to the backcountry will see evidence of a natural wind slab avalanche cycle from recent storm snow and strong southwest winds.
+20 cm of new snow in the alpine is being redistributed by southwesterly winds into wind slabs in lees. The recent storm snow sits on previously wind-affected surfaces. Below this, a melt-freeze crust is found on sun-exposed slopes and everywhere below 1600 m.
Several 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 from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine terrain.
In general, the snowpack is weak and shallow in this area with an average snowpack depth of 100 cm at treeline.
Tuesday Night
Cloud with isolated flurries, 1-3 cm accumulation. Alpine temperatures drop to -8 C. Ridge wind southwest 40-60 km/h. Freezing levels fall to valley bottom.
Wednesday
Mainly cloudy with sunny periods. Ridge wind southwest 60 km/h easing in the afternoon. Alpine temperatures -10 C. Freezing level 800 meters.
Thursday
Mainly cloudy with sunny periods. Moderate ridge wind from the southwest picks up to 50-70 km/h in the evening. Alpine temperatures rise to -2 C. Freezing level rise to 1500m.
Friday
Mainly cloudy with sunny periods. Moderate ridge wind from the southwest picks up to 50-70 km/h in the evening. Alpine temperatures rise to -3 C. Freezing level 1200m.
More details can be found in the Mountain Weather Forecast.
