Avalanche Forecast

Issued: Dec 24th, 2016 3:35PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada cgarritty, Avalanche Canada

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.

Problems

Wind Slabs

An icon showing Wind Slabs
Recently formed wind slabs have been masked by a thin layer of new snow. Potential exists for a wind slab avalanche to trigger deeper weaknesses in the snowpack.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Watch for signs of instability such as whumpfing, or cracking. Be increasingly cautious on sun exposed slopes.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 25th, 2016 2:00PM

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