Watch for newly formed 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.
An additional 5-10 cm of snow and ongoing strong southwest winds are building fresh wind slabs in treeline and alpine lees. Avoid lee and cross-loaded terrain.
Keep in mind that storm 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. Wind slab avalanches could step down to this layer initiating very large avalanches. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain.
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 the weekend.
Our greatest concern lies with the potential for large natural and human-triggered deep persistent slabs. 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.
Overnight flurries bring this weekend's storm snow totals to 40-50 cm. Strong southerly winds have stripped exposed windward areas and deposited pockets of wind slabs in lees. The recent storm snow sits on previously wind-affected snow. 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.
Monday Night
Mainly cloudy with isolated flurries, 2-8 cm accumulation. Alpine temperatures rise to -5 C. Ridge wind southwest 60 km/h. Freezing level slowly drop to 500 meters overnight.
Tuesday
A mix of sun and cloud with isolated flurries, trace accumulation. Alpine temperatures drop to -7 C. Ridge wind southwest 40-60 km/h. Freezing level 1000 meters.
Wednesday
A mix of sun and cloud with isolated flurries, trace accumulation. Ridge wind southwest 60 km/h easing in the afternoon. Alpine temperatures rise to -7 C. Freezing level 800 meters.
Thursday
A mix of sun and cloud with isolated flurries, trace accumulation. Moderate ridge wind from the southwest picks up to 50-70 km/h in the evening. Alpine temperatures rise to -7 C. Freezing level rise to 1500m.
More details can be found in the Mountain Weather Forecast.
