Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain.

Thursday night: Cloudy with continuing flurries bringing about 5 cm of new snow, possibly closer to 15 cm in isolated locations. Light to moderate south winds.

Friday: Mainly cloudy with isolated flurries and a trace of new snow. Light southwest winds. Alpine high temperatures around -10.

Saturday: Cloudy with isolated flurries and a trace of new snow. Light to moderate south winds, increasing over the day and overnight. Alpine high temperatures around -9.

Sunday: Cloudy with flurries bringing about 5 cm of new snow, increasing a bit overnight. Moderate southeast winds, possibly strong south in the alpine. Aline high temperatures around -6.

We're just beginning to receive reports of newly formed small (size 1) wind slabs releasing with skier traffic as a result of recent snowfall and wind. Loose dry sluffing of our new snow in steep terrain has been more widely reported. With snowfall continuing overnight, both of these hazards are expected to be significantly greater on Friday.

Notably, another small (size 1) persistent slab was triggered by a skier in the Valhallas on Wednesday. This occurred on a steeper north aspect at 2150 metres, where the failure plane was about 30 cm deep. This follows a recent pattern of isolated releases on this layer. 

Although the Valhallas stand out in these reports, similar snowpack conditions exist in other parts of the region, particularly in the Selkirks, where operators are continuing to watch this layer closely. Concern for this problem is increasing in line with loading from new snow and increased avalanche activity in shallower snowpack layers.

20-40 cm of new low density snow is expected to have accumulated in the region by Friday morning. The new snow has buried a widespread layer of surface hoar that has grown up to 10 mm in sheltered areas around treeline. 

This surface hoar grew on a variety of surfaces that include wind affected surfaces in exposed terrain as well as more variably wind affected and faceted snow in more sheltered terrain. A thin sun crust may be found on steep solar aspects. Below 1700-1800 m, 30-50 cm of snow is settling above a decomposing melt freeze crust.

Observers continue to find a preserved layer of surface hoar down 35-70 cm in sheltered, open slopes at and below treeline. Most recent reactivity has been reported in the Selkirks and Valhallas toward the south of the forecast region (see avalanche summary). There is concern for the areas this layer remains preserved now that it is being stressed by a significant load of new snow.

Deeper in the snowpack, a couple of older persistent weak layers may still be identifiable from late and early December, consisting of surface hoar and a crust with faceted snow and buried anywhere from 100-200 cm deep. Prolonged periods of inactivity and unreactive snowpack test results suggest that these layers have trended towards dormancy.

• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Watch for signs of slab formation throughout the day.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.