More new snow, strong wind, and rising temperatures are expected to maintain a widespread natural avalanche cycle in the region on Sunday. Travel in avalanche terrain is not recommended.
Ongoing snowfall will continue to build storm slabs through Sunday. Strong winds and rising temperatures will aid slab formation and promote natural avalanche activity. The heaviest snowfall and greatest danger will be focused toward the south of the region.
Warming temperatures and possible rain will promote wet loose avalanche activity at lower elevations on Sunday. These are most likely to occur on steep slopes and may initiate naturally or with a human trigger.
Saturday night: Cloudy with continuing snowfall bringing 20-40 cm of new snow. Strong southwest winds.
Sunday: Cloudy Continuing snowfall bringing 10-25 cm of new snow, transitioning to light rain below about 1500 metres. Strong southwest winds. Alpine temperatures around -1 with freezing levels reaching 1800 metres by afternoon.
Monday: Cloudy with flurries bringing about 10 cm of new snow. Moderate south winds. Alpine high temperatures around -3 with freezing levels to 1400 metres.
Tuesday: Cloudy with flurries bringing 5-10 cm of new snow. Moderate south winds. Alpine high temperatures around -5 with freezing levels to 1000 metres.
No avalanches from the current storm have yet been reported, but ongoing snowfall and strong wind have been forming a widespread new storm slab problem in the region. Natural avalanches are expected to have become increasingly widespread in areas that saw upwards of 25 cm of new snow by the end of the day Saturday.
Similar conditions are expected to persist through Sunday, with a further rise in temperatures expected to make slabs extra touchy while bringing wet loose avalanche concerns into the mix at lower elevations.
Increasing load as well as surface avalanches will steadily increase concern for the possibility of very large avalanches releasing on our weak basal snowpack layer.
2-day snow totals over the region are expected to reach 50-80 cm by the end of the day on Sunday, with the greatest accumulations focused toward the south of the region. The new snow has buried recent wind slabs and wind-affected surfaces in exposed areas at all elevations and soft, low density snow in sheltered areas. It adds to just over a meter of storm snow that has fallen in the last week.
Professionals in the region are continuing to track a pair of weak surface hoar layers from mid and late December. Previously 70 to 160 cm below the snow surface, these layers have given increasingly stubborn results in snowpack tests but may remain sensitive to human triggering in places where the snowpack goes from thick to thin, steep unsupported slopes, and around sheltered shallow, rocky start zones.
The beginning of the season had less precipitation than usual, which led to a layer of sugary faceted grains as well as a hard melt-freeze crust near the base of the snowpack. In a more seasonally normal winter we wouldn't be thinking about this interface, but it has produced large, destructive natural avalanches as recently as January 11th.
Concern for very large avalanches releasing over this weak basal layer will increase as loading from new snow, wind, and rising temperatures strain the snowpack and cause avalanche activity in surface layers.
