Avalanche Forecast

Issued: Dec 20th, 2017 4:26PM

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

Avalanche Canada mbender, Avalanche Canada

Expect the recent storm slab to become more reactive as it continues to settle and consolidate.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

THURSDAY: Mainly cloudy with flurries, accumulation 5cm / wind light north / alpine temperature -11 FRIDAY: Mainly sunny / wind moderate north / alpine temperature -17SATURDAY: Mainly sunny / wind moderate northwest / alpine temperature -11 

Avalanche Summary

Numerous natural loose dry avalanches to size 1.5 have been reported running in steep terrain. These have been running in the recently fallen new snow. That being said, as this recent new snow sitting on top of a variety of weak layers starts to settle, expect avalanche activity to increase. If you have any observations, please submit them to the Mountain Information Network (MIN).

Snowpack Summary

20-40cm of new snow accumulating through last weekend 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 seen previous surface hoar development, such as sheltered areas at and below tree line and sheltered northerly aspects in the alpine. Additionally, any steep solar aspects where the surface hoar may be sitting on sun crust should be considered areas where this weak layer may be likely to trigger. A crust which was formed by rain in late November is a major feature in the snowpack and is down approximately 60-80cm 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 northeast have formed windslabs in the lee of terrain features on a variety of aspects.
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

An icon showing Storm Slabs
This storm slab may be sitting on a buried weak layer of feathery surface hoar crystals, especially in sheltered areas between 1600 and 2000m along with sheltered northerly aspects in the alpine. Expect it become more reactive as it settles.
Buried surface hoar may be preserved on open slopes and convex rolls at and below tree lineWatch for whumpfing, shooting cracks, or signs of recent natural avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

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