Recent winds have been building avalanche hazard while cold temperatures have helped snowpack weaknesses to persist. Stay cautious of wind slabs and keep the persistent slab problem on your mind in shallow snowpack areas.
Weather Forecast
Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Winds light to moderate from the southwest. Alpine temperatures of -7.Monday: Mainly cloudy with isolated flurries and a trace of new snow. Winds moderate to strong from the southwest. Freezing level rising to 1100 metres and alpine temperatures around - 4.Tuesday: Periods of snow bringing approximately 15 cm of accumulation. Winds strong from the south. Freezing levels rising to (and possibly exceeding) 1500 metres with alpine temperatures near 0.
Avalanche Summary
Size 1-1.5 wind slab avalanches have continued to run naturally in steep terrain, with the most recently reported activity observed on north aspects near Valemount.
Snowpack Summary
Cold and clear weather has promoted both faceting of surface snow as well as the growth of surface hoar that has been reported to be up to 7mm in size below treeline. Below the surface, recent new snow has been redistributed by moderate to strong southwest and more recent northerly winds in exposed upper areas. In deeper snowpack parts of the region, the mid-December facet layer lies up to 120 cm below the surface. In these areas, professionals feel this layer has generally gained considerable strength. In shallower areas, particularly those in the southeast (Allen Creek), North (Sugarbowl) and likely some western areas around Quesnel and Barkerville, the snowpack is likely a lot more suspect, with a thicker, more pronounced facet layer buried only 50-60 cm below the surface. In shallow snowpack areas such as these, careful evaluation of this facet layer is a prerequisite to any push into steeper terrain.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.