Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

New Year, New Snow!

Overnight Friday: Cloud cover increasing in the evening, overcast by the morning. Light northerly winds will shift to the west and increase moderate to strong in the early morning. Temperatures rising to -13 C in the alpine. 

Saturday: Cloudy skies with flurries, up to 5 cm of accumulation. Winds strengthening throughout the day, moderate to strong from the southwest. Temperatures rising with an alpine high of -8 C in the afternoon. Overnight the storm will intensify with continued strong to extreme winds accompanying 20-40 cm of new snow, freezing levels rising to 400m.

Sunday: A stormy day. Another 10-30cm of new snow accompanied by strong to extreme southwest winds. Freezing levels rising to 700m by mid afternoon. Continued snowfall overnight with 10-20 cm of new snow accumulation. Winds easing moderate to strong from the southwest.

Monday: The storm will begin to taper. Cloudy with flurries. Moderate southwest winds with another 5-10 cm of new snow. 

Earlier in the week, there have been reports of several small (size 1) and a few large (size 2) wind slab avalanches in the Duffey Lakes area. These included natural avalanches on south aspects that were the direct result of reverse loading.

Over the past few weeks, we have been concerned about a potential persistent weak layer in the region. While most of the relevant observations have come from the neighbouring Sea To Sky region, similar types of avalanches were observed in northern parts of the region over a week ago. We suspect it would still be possible to trigger avalanches on this layer in isolated terrain features such as shallow rocky start zones around treeline elevations. 

Learn more about how this persistent weak layer is developing in our latest forecaster blog!

Persistent cold temperatures may have made cornices facetted and weak, highlighting the importance of avoiding overhead hazard and giving them a wide berth when travelling at ridge crest. Cornice failures can create a large load on the snowpack and trigger persistent weak layers.

This week, variable winds have heavily impacted the snow in open alpine and treeline terrain, leaving wind slabs of a variety of reactivity and hardness on almost all aspects. Today, moderate to strong southwest winds and a light amount of new snow will continue to transport available snow into fresh, reactive wind slabs in the alpine and treeline.

In sheltered areas, it may be possible to find up to 20cm of low density, faceting snow. This new snow overlies a weak layer of near-surface facets and in isolated areas surface hoar, formed by the persistent cold temperatures earlier in the week.

A recent MIN report from the Duffey found a 40 cm deep surface hoar layer. It was found in sheltered north-facing treeline terrain and was reactive in snowpack tests. There are no other reports of this weakness, so it is most likely a relatively isolated instability.

A weak layer of facets (sugary snow) may be found over a crust that formed in early December (down 70-150 cm). In the neighbouring Sea to Sky region this layer has been particularly reactive at treeline and low alpine elevations, between 1800-2100 m. We have seen a decreasing trend in avalanche activity on this layer as it has transitioned into a tricky low-probability high-consequence problem (see the problem description and travel advice for suggestions).

The lower snowpack is well settled. Snowpack depth at treeline ranges from 160-250cm.

• Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
• Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.