Avalanche Forecast

Issued: Dec 20th, 2017 4:21PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs and Storm Slabs.

Avalanche Canada mbender, Avalanche Canada

Choose conservative terrain in the coming days as recent storm slab continues to settle and consolidate.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

THURSDAY: Cloudy with flurries, accumulations 5cm / wind light to moderate northwest / alpine temperature -8FRIDAY: Mix of sun and cloud / wind moderate north / alpine temperature -10SATURDAY: Mainly sunny / wind moderate northwest / alpine temperature -11

Avalanche Summary

Recent reports indicate a few size 1-1.5 remote triggered (triggered from a distance) avalanches in the alpine and tree line. These are isolated to this past week's storm snow. Additional reports show natural wind slab avalanches to size 2 in the alpine on north and east aspects in the alpine along with skier triggered and natural size 1 loose snow avalanches in steep terrain at tree line and in the alpine. As snow amounts continue to settle and consolidate in the coming days, expect to see avalanche activity continue.

Snowpack Summary

20-50cm of new snow accumulating over the past week sits on a wide variety of old surfaces including large surface hoar (weak, feather-like crystals), hard crusts formed by sun or wind, and sugary facets. As the snow load builds and slab properties develop, it will be important to monitor how the new snow is bonding to the old surfaces. Most concerning would be areas that have had previous surface hoar development, such as sheltered areas at and below tree line and/or sheltered northerly aspects in the alpine. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 40-60cm at tree line elevations. Snowpack tests suggest the snow above is currently bonding well to it.Snowpack depth decreases rapidly below tree line. Look out for early season hazards such as rocks, stumps, and open creeks.

Problems

Wind Slabs

An icon showing Wind Slabs
New snow combined with moderate westerly winds will have formed wind slabs in the lee of terrain features
Travel on ridges and/or ribs to avoid wind loaded slopes belowBe cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Expect the recent storm slab to become more reactive as it continues to accumulate, settle and consolidate.
Use conservative route selection, choose moderate angled and supported terrain with low consequence.Buried surface hoar may be preserved on open slopes and convex rolls at and below tree lineWatch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 21st, 2017 2:00PM

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