Hiding from alpine hazards by tucking into treeline is not always a winning strategy - our persistent slab problem has proven particularly touchy at mid-elevations. This layer is difficult to assess, so choose terrain that won't punish you for an incorrect analysis.
Rider triggerable wind slabs may be found on north and east aspects at treeline and above. Recent extreme winds may have focused slab formation at lower elevations than is typical.
30 to 70 cm of snow sits over a facet-crust weak layer combination that is possible to human trigger. Recent observations demonstrate the potential for this problem to be triggered remotely and propagate far and wide.
This layer is most reactive between 1800 and 2000m, potentially due to the presence of surface hoar on the crust, but this layer be found above and below this elevation band. Avoid avalanche terrain at this elevation and be aware of slopes above that could be remotely triggered.
Monday night: Cloudy with isolated flurries. Moderate west winds.
Tuesday: Cloudy with flurries bringing up to 5 cm of new snow, continuing overnight. Moderate west winds, potentially strong in the alpine. Treeline high temperatures around -3 with freezing levels hovering near 1300 metres.
Wednesday: Sunny with no snow expected. Light to moderate northwest winds. Treeline high temperatures around +2 with freezing levels rising to 3000m in the afternoon.
Thursday: Sunny. Light to moderate northwest winds, potentially strong in the alpine. Treeline high temperatures around +4 with freezing levels remaining around 3000 metres.
On Saturday in the South Coast Inland region a fatal size 3 (very large) skier triggered avalanche was reported in the Duffey Lake area. It ran on the persistent weak layer from late January described in our snowpack summary. This avalanche was triggered in a upper treeline feature on a northeast aspect and showed significant propagation. Click here to read a more detailed report. This is the same layer that was responsible for a skier triggered size 2.5 avalanche last week on Rainbow mountain. Several smaller skier triggered avalanches on this layer were also reported throughout the week. Most of the avalanche activity on this layer has taken place between 1800m and 2000m but it can be found above and below this elevation band.
We anticipate the skier triggering potential of this avalanche problem to sustain through Tuesday, followed by a significant increase in the likelihood of avalanches on this layer for Wednesday onward.
Extreme southwest winds over Sunday night may have formed new wind slabs in leeward terrain, however this was likely hampered by already extensive recent wind redistribution of surface snow as well as the recent formation of surface crusts at lower elevations and on solar aspects.
Including 10-20 cm of snow we received Friday, our January layer of facets on crust is now buried down 30 to 70 cm. This layer is widespread between 1800 m and 2000 m, but may be found just above or below this elevation band. It has produced several human and remote triggered avalanches in the past few days. In sheltered terrain at treeline and above, surface hoar may also be found on this layer and it will certainly promote slab reactivity where it exists.
