A fine day Thursday before another storm rolls in on Friday. A weak layer lurks below the surface, so cautious terrain selection is required.
A surface hoar layer is buried around 40 cm below the surface. New snow or the weight of a rider could easily trigger avalanches on this layer.
Storm slabs will form once again with Friday's weather system. Good amounts of new snow and wind with rising temperatures will make avalanches very likely on Friday.
Wednesday night: 4-8 cm new snow with strong westerly ridgetop winds. Freezing level lowering to valley bottom.
Thursday: Dry, with a mix of sun and cloud. Strong northwesterly winds. Treeline temperatures around -12°C.
Friday: 15-20 cm new snow with rain at lower elevations. Freezing level around 1600 m. Strong southerly winds.
Saturday: 10-15 cm new snow. Freezing level lowering to valley bottom. Strong southwesterly winds.
A wide, but relatively thin avalanche that involved a skier was reported from the Farm on December 29: https://avalanche.ca/mountain-information-network/submissions/a38b031a-7845-48fd-acdb-a0c00e9e2339. A similar event was reported from Pine Pass: https://avalanche.ca/map/forecasts/north-rockies?panel=mountain-information-network-submissions/4fc391f2-81cc-4725-a960-b2d71388ba70. These and several other avalanches reported Dec 29 to Dec 31 appear to have failed on a layer of surface hoar buried 30-40 cm below the surface.
A weak layer of feathery surface hoar is buried around 40 cm below the surface. Avalanches have already been reported to have run on this layer and it is also showing "sudden" reactivity in snowpack tests. It is still at a burial depth where further storms will most likely increase, rather than decrease its reactivity.
There are a pair of weak layer in the middle of the snowpack. One is a surface hoar layer that appears to be gaining strength. The other is a layer of facets that lies above a relatively thin crust. Both these layers appear to be gaining strength.
The lower snowpack contains several crust layers, which could be a concern in shallow areas along the eastern slopes of the region.
