Avalanche Forecast

Issued: Dec 21st, 2017 4:02PM

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 the recent storm slab continues to settle and consolidate.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

FRIDAY: Mix of sun and cloud / wind light to moderate north / alpine temperature -13 SATURDAY: Mainly sunny / wind moderate northwest / alpine temperature –11 SUNDAY: Mix of sun and cloud / wind light to moderate north / alpine temperature -9

Avalanche Summary

Reports from the past few days  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 and storm 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

30-50cm 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 60-100cm 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
Recent west and northwest winds switching to north and east have formed windslabs in the lee of terrain features on a variety of aspects
Be cautious as you transition into wind affected terrain.Travel on ridges and/or ribs to avoid wind loaded slopes belowBe aware of areas that have been reverse loaded by winds

Aspects: All aspects.

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 settle and consolidate.
Watch for signs of instability such as whumpfing, or cracking. Buried surface hoar may be preserved on open slopes and convex rolls at and below tree lineUse conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 22nd, 2017 2:00PM