Avalanche danger will increase over the day as snowfall and strong winds layer new wind slabs over the surface at higher elevations. New snow accumulations will become increasingly unstable if the sun pokes out in the afternoon.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain
Weather Forecast
Friday night. Flurries bringing 7-10 cm of new snow. Light to moderate southwest winds, increasing to extreme at ridgetop.Saturday: Cloudy with continuing flurries bringing another 7-10 cm of new snow. Moderate to strong west winds. Freezing level to 1600 metres with alpine high temperatures around -4.Sunday: A mix of sun and cloud. Light northwest winds. Freezing level to 1700 metres with alpine high temperatures around -5.Monday: Sunny. Light southeast winds. Freezing level rising to 2300 metres with alpine high temperatures around 0 to +1.
Avalanche Summary
Reports from Thursday were limited to a couple of size 2 storm and wind slabs, 30 and 50 cm deep, respectively. The storm slab released naturally while the wind slab was ski cut from a steeper north aspect in the alpine.Tuesday's reports included observations of numerous natural wind slab release from size 1-2 on north through east aspects in the alpine. A skier triggered size 2 storm slab resulted in a near miss. Another recent very large (size 3.5) storm slab was also observed to have released on a large, wind-loaded alpine feature. Reports from Monday were limited by poor visibility but included one small (size 1, 20 cm deep) ski cut wind slab as well as skier-triggered loose snow releases on steeper slopes. The rough dividing line between loose wet and loose dry activity was about 2000 metres.In addition to heightened storm slab activity following regular snowfalls, observations from late last week also showed a pattern of heightened cornice failure activity. Looking forward, another round of snowfall is expected to introduce new surface instabilities over Friday night and Saturday.
Snowpack Summary
New snow is forecast to accumulate above a new melt freeze crust that can now be found on the surface on all but north aspects above about 2200 metres. Below it, about 50-70 cm of settled storm snow overlies a supportive crust which shares similar distribution to the surface crust.Within this storm snow there are a few different crusts with the shallowest of these (down about 20-40 cm) now a limited concern as recent warm temperatures have promoted settlement and bonding in the upper snowpack. Recent wind slabs on the surface at higher elevations should be on a similar stabilizing track.With warm daytime temperatures and poor overnight recovery of cold temperatures, there is some lingering concern around the mid-March weak layer in the alpine where it is found 90 to 120 cm deep. This buried crust/surface hoar layer was widely reactive but is now trending towards dormancy. It should be kept in the back of our minds for its capability to produce large avalanches should it be triggered with a heavy load such as a cornice collapse.Deeper persistent weak layers from December and January are generally considered dormant at this time but may be reactive to very large triggers.
cgarritty,
Avalanche Canada
