Avalanche Forecast

Issued: Dec 22nd, 2015 8:11AM

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

jlammers, Avalanche Canada

Cariboos.

Low Danger does not mean No Danger. Make observations continually as you travel.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

A benign yet cool weather pattern has set up and will continue for the forecast period. For each day, expect a mix of sun and cloud with isolated flurries. Ridgetop winds are expected to remain light while alpine temperatures should remain between -12 and -16.

Avalanche Summary

Evidence of a fairly widespread cycle of soft wind slab avalanches in the size 1-1.5 range was observed in extreme terrain on Monday. The avalanches occurred in response to new snow and wind over the weekend.

Snowpack Summary

20-40cm of low-density snow overlies soft wind slabs which formed last weekend. The few observations we've had suggest a good bond within the storm layers in the upper snowpack. I'd still remain cautious in upper elevation lee terrain where buried wind slabs may still be sensitive to human triggering. Between 80 and 130cm below the surface you'll likely find a weak layer of well-developed surface hoar which was buried in early December. This layer is most widespread and reactive at lower elevations (between 1100m and 1800m.) Snow pit tests suggest that human triggering of this interface has become less likely. That said, if it does fail the overlying slab is stiff enough to propagate over a wide distance. Below this layer, the snowpack is thought to be generally strong and well-settled.

Problems

Wind Slabs

Low-density powder may be hiding wind slabs which formed during stormy weather on the weekend. They may have gained considerable strength, but I'd remain cautious on high-elevation lee slopes. Loose dry avalanches are also possible in steep terrain.

The recent snow may now be hiding windslabs that were easily visible before the snow fell.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A layer of buried surface hoar can be found between 1400m and 1800m. Although this layer has become less likely to trigger, I'd remain cautious on steep roles in cut-blocks and open glades below treeline.

Avoid open slopes, convex rolls, burns, cutblocks and terrain traps when traveling below treeline. >

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 23rd, 2015 2:00PM