Avalanche Forecast

Issued: Dec 18th, 2014 8:15AM

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

rbuhler, Avalanche Canada

Cariboos.

Conditions will change rapidly as we enter the weekend. Watch for sluffing from steep terrain at all elevations and for signs of early wind slab development in the alpine.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

The first wave of precipitation is expected to reach the interior late Thursday night or early Friday morning. 10-20cm of new snow is expected in the south of the region for Friday. Freezing levels are expected to be 1200-1500m and alpine winds moderate from the SW. A weak ridge will keep Friday night and Saturday morning mainly dry before the next storm front arrives on Saturday afternoon or evening. Freezing levels on Saturday will rise to around 1500m or so and alpine winds will increase to strong from the SW. Saturday night and Sunday should yield another 20-40cm of snowfall up high. Freezing levels on Sunday may rise as high as 2000m and winds will remain strong.

Avalanche Summary

No new avalanches have been reported since last weekend. On Sunday, snowmobiles remotely triggered a persistent slab with a crown depth around 1.5m in the Allan Creek area. On Saturday, two size 2 remotely triggered persistent slab avalanches were reported. These were triggered from 250m away and released 80-100cm down on the old rain crust from early November. These occurred around 2000-2200m elevation on NW aspects.

Snowpack Summary

The new snow sits on a layer of large surface hoar. Up to around 1800m elevation this surface hoar sits on a hard rain crust. Above 1800m the surface hoar sits on well settled and faceted snow. The early November crust/facet layer is down around 1 m in the south of the region, probably less in the north.

Problems

Loose Dry

The new snow will form a poor bond with the crust/surface hoar interface and fast sluffing is expected from steep terrain. Watch for early stages of wind slab development in the alpine.

Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

The likelihood of triggering a deep persistent slab has decreased but the consequences remain very high. Be wary of any slopes that did not release during the storms. Heavy triggers such cornice falls may be able to trigger a deep weak layer.

Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 19th, 2014 2:00PM