Fresh storm slabs will continue to build on Saturday, but they are only half of the picture. Persistent weaknesses deeper in the snowpack still can't be trusted - especially with increasing load stacking up above.
Summary
Confidence
Moderate -
Weather Forecast
Saturday: Periods of snow bringing 15-20 cm of new snow. Moderate to strong south winds. Freezing level to 1200 metres with alpine temperatures around -3. Sunday: Periods of snow bringing approximately 15cm of new snow, mainly in the evening. Moderate to strong southwest winds. Freezing level to 1400 metres with alpine temperatures around -2. Monday: Flurries bringing another 10-15 cm of new snow. Moderate to strong southwest winds. Freezing level to 1800 metres with alpine temperatures around -1.
Avalanche Summary
Reports from Thursday included further observations of reactive wind slabs in immediate lee terrain occasionally releasing to Size 1 under skier traffic and with ski cutting.Reports from Wednesday revealed widespread natural avalanche activity, with Size 1-2.5 releases noted throughout the region. North aspects were most active. Ski cutting and explosives control in the Whistler area yielded numerous results with crown fractures ranging from 20-40 cm deep. Loose snow sluffing from steep terrain was noted on both days. Looking forward to Saturday, expect recently formed storm slabs to remain reactive and for stability to deteriorate over the day with increasing snowfall, winds, and rising temperatures. While the bond at mid-February interface remains questionable, the likelihood of large persistent slab avalanches will also increase as forecast snowfall and wind add load to the snowpack.
Snowpack Summary
Another 20-30 cm of new snow fell over Thursday night, bringing typical storm accumulation from the past week to 80-130 cm. Moderate to strong southwest wind over Tuesday and Wednesday ramped up to extreme over Thursday night. These winds have increasingly redistributed our recent storm snow and formed touchy new storm slabs in lee terrain at higher elevations. The recent storm snow has settled into a slab that sits over the mid-February weak layer which consists of facets and/or surface hoar overlying a thick crust. In wind loaded terrain, this layer may be down 180 cm or more. Recent observations suggest this layer is still reactive and capable of producing wide propagations if triggered. We have been in an incremental loading scenario over the past week and this layer will continue to be tested as new snow continues to accumulate. Below the crust layer, the mid and lower snowpack are well settled and strong.
cgarritty,
Avalanche Canada
