Watch for signs of instability as the sun pokes out on Sunday and snowfall begins on Monday.
Summary
Confidence
Moderate - Intensity of incoming weather systems is uncertain on Monday
Weather Forecast
Sunday: Cloudy with sunny periods and no new snow. Winds light from the west. Freezing level at valley bottom with alpine temperatures to -11.Monday: Flurries with up to 10cm of new snow. Winds moderate from the southwest. Freezing level at valley bottom with alpine temperatures to -10.Tuesday: Flurries with up to 10cm of new snow. Winds moderate to strong from the southwest. Freezing level rising to 800 metres and alpine temperatures to -8.
Avalanche Summary
Explosives control in the south of the region on Saturday produced several size 2 avalanches with crown depths up to 20cm. Friday's observations included a natural size 1 avalanche releasing storm snow above the December 18 interface in steep northwest-facing alpine terrain. Observations from earlier in the week include wind slab avalanches triggered from explosives control running on the same storm/old snow interface to size 2 at treeline and above.
Snowpack Summary
10-15cm of new snow over Thursday and Friday has brought storm snow totals to 30-60cm since snowfall began at the beginning of the week. The storm snow has buried old wind slabs, facets and surface hoar. There is some uncertainty regarding how the new snow is bonding to old surfaces which formed during last week's cold clear period. Moderate to strong winds have loaded leeward features with wind slabs. A widespread crust that was buried in November is now 80-100cm deep in the snowpack. Recent tests show variable results with this persistent weakness. Some show results as hard and resistant and others show a sudden character, suggesting it may be likely to propagate if triggered from thin, rocky areas.
cgarritty,
Avalanche Canada
