Avalanche Forecast

Issued: Dec 21st, 2017 3:51PM

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

mbender, Avalanche Canada

Cariboos.

Choose conservative terrain in the coming days due to the presence of a persistent slab problem. This problem is more pronounced south Valemount where recent snowfall amounts have been higher.

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 -17 SATURDAY: Mainly sunny / wind moderate north / alpine temperature –16 SUNDAY: Mix of sun and cloud / wind light to moderate north / alpine temperature -13

Avalanche Summary

Numerous natural loose dry avalanches to size 1.5 have been reported running in steep terrain in recent days. 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 continues 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 70-100cm 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

Recent west and northwest winds switching to north and east have formed windslabs in the lee of terrain features on a variety of aspects.

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.Be aware of areas that have been reverse loaded by winds

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Expect persistent slabs to be become more reactive as recent new snow settles into a slab. Likely spots are sheltered open areas at and below tree line or sheltered northerly aspects in the alpine.

Watch for whumpfing, shooting cracks, or signs of recent natural avalanches.Buried surface hoar may be preserved on open slopes and convex rolls at and below tree line

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

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