Avalanche Forecast

Issued: Dec 26th, 2013 7:52AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.

Peter, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Friday: Moderate snowfall 10-15 cm. The freezing level is around 1200-1400 m and winds are moderate gusting strong from the southwest. Saturday: Mainly cloudy with a chance of flurries and possible sunny breaks. The freezing level drops to around 800-1000 m and winds are moderate from the northwest. Sunday: Mainly cloudy with a chance of flurries or light snow. The freezing level is near valley bottom.

Avalanche Summary

We've received recent reports of the basal weaknesses causing large natural avalanche releasing on or near the ground on N to NE aspects. Human triggering of large destructive avalanches is possible at this time.

Snowpack Summary

An additional 20 cm of snow has fallen accompanied by moderate to strong W-SW winds and mild temperatures. New dense wind slabs are likely in exposed lee terrain at and above treeline. Up to 80cm of snow now sits on a variety of weaknesses from early December (surface hoar, faceted snow, and/or a crust). An older layer of surface hoar or facets from late November can be found deeper in the snowpack. Recent snowpack tests results vary but some are showing this layer "pop" with medium loads, indicating a potential for human triggering.Snowpack depths vary, but in general up to 150 cm of snow can be found at treeline, with 100-200 cm in the alpine. In many places we're still dealing with a relatively thin snowpack so there's not a whole lot of snow between riders and the sugary snow (facets) near the ground. A facet/crust combo has been recently active in parts of the region.

Problems

Storm Slabs

The new snow make take a couple days to settle and stabilize. Watch for fresh new wind slabs in exposed north and east facing terrain at higher elevations.

Choose well supported terrain without convexities.>Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

Persistent weaknesses exist in the upper and mid-snowpack and could be triggered by the weight of a skier or rider.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Be aware of the potential for large, deep avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Deep Persistent Slabs

Triggering a weakness near the base of the snowpack is unlikely, but if triggering, the resulting avalanche would be very large and dangerous. Be cautious in areas with a shallow or variable snowpack, especially higher north facing terrain.

Avoid rock outcroppings, steep convexities and anywhere the snowpack feels thinner than average.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Dec 27th, 2013 2:00PM