It's a good time to take a big step back from avalanche terrain. New snow and wind are building fresh wind slabs and adding load to a weak and volatile snowpack. It's uncertain when the tipping point will be reached for large, destructive avalanches to occur and this uncertainty demands a conservative approach and low-consequence terrain selection.
Strong northwesterly winds will transport snow and form fresh wind slabs in the alpine and treeline.
Be aware that wind slabs could step down to deeper layers.
The most concerning layer in this region is a layer of weak facets near the bottom of the snowpack. This layer is most likely to be triggered at upper treeline/alpine on shallow terrain features and may become increasingly reactive as new snow and wind add load to the snowpack.
Last week, our field team observed several small wind slab avalanches. Check out their latest MIN for more details.
Looking forward to this week, reactive wind slabs are expected to form but concern for large natural and human-triggered deep persistent slab avalanches is at the forefront of our minds. A series of incoming storms will be slowly adding load to a shallow, weak snowpack with multiple layers of concern. It is uncertain when the "tipping point" for large destructive avalanches will be reached but this uncertainty demands conservative and low-consequence terrain selection. Check out this video on incremental loading to learn more.
Please continue to send in your observations through the MIN.
Overnight snowfall has brought 5-15 cm of new snow. The accompanying northwest winds will affect wind-exposed terrain and build fresh wind slabs in lee terrain features. Below the new snow, a sun crust may be found on steep solar aspects.
At lower elevations, a rain crust exists down around 20cm, with reported elevations extending up to 1800 m in the Cariboos and roughly 1200 m in the northern part of the region.
Snowpack depths are shallower than normal, and several buried weak layers have been a concern over the past few weeks. One is a recently buried surface hoar layer found 30 to 60cm deep in sheltered terrain features at treeline and above. At this same depth, a crust exists on steep south-facing slopes. Another layer of facets, crust, and surface hoar was buried around Christmas and is now 50 to 90cm deep. Finally, a layer of large, weak facets buried in November is found near the bottom of the snowpack. This layer is likely most problematic in alpine terrain, where shallower avalanches could scrub down to these basal facets.
Sunday night
Cloudy with increasing snowfall, 5-10 cm of accumulation. Alpine temperatures drop to a low of -10 C. Ridge wind northwest 40-60 km/h. Freezing level at valley bottom.
Monday
Mainly cloudy with continued snowfall, 5 cm of accumulation. Alpine temperatures rise to -7 C. Ridge wind northwest 45-70 km/h. Freezing level rises to 1100 m.
Tuesday
Cloudy with snowfall, 5-10 cm accumulation. Alpine temperatures reach a high of -6 C. Ridge wind northwest 40-60 km/h. Freezing level rises to 1100 m.
Wednesday
Mainly cloudy with snowfall, 5-15 cm of accumulation. Alpine temperatures reach a high of -1 C. Mostly light westerly ridge wind occasionally gusting to 35 km/h. Freezing level rises to 1400 metres.
More details can be found in the Mountain Weather Forecast.
