Avalanche Forecast

Issued: Dec 28th, 2013 7:34AM

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

Peter, Avalanche Canada

Cariboos.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Tonight and Sunday: Periods of snow around 5-10 cm. The freezing level is near valley bottom and winds are moderate gusting strong from the W-NW. Monday: Flurries or periods of snow 5-10 cm. The freezing level is around 1000-1200 m and winds are light to moderate from the west. Tuesday: Cloudy with a chance of flurries. The freezing level is near valley bottom.

Avalanche Summary

Reports from the past couple days are very limited; however, it's likely that the combination of new snow, wind, and mild temperatures kicked off a natural avalanche cycle in some areas. The additional load may have also been enough to trigger deep persistent weaknesses in isolated areas.

Snowpack Summary

Storm snow totals vary across the region but are generally between 30 and 40 cm. Freezing levels peaked near 1600 m on Friday and have since dropped significantly. A new surface crust is possible at lower elevations. Expect to find touchy wind slabs in exposed lee terrain at and above treeline. A couple buried weak layers (surface hoar or facets) are now down 80-100 cm deep. Recent snowpack test results on these layers vary, but some are showing this layer "pop" with easy to 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 (thanks to a windy early season) so there's not a whole lot of snow between riders and the sugary snow (facets) near the ground. The basal facet/crust combo has been recently active in parts of the region and continues to give easy to moderate results in snowpack tests.

Problems

Persistent Slabs

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

Whumpfing is direct evidence of a buried instability.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

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

Deep Persistent Slabs

There is lingering potential for full depth avalanches due to the presence of a weak facet/crust layer near the base of the snowpack. Triggering is unlikely, but if triggered the consequences could be very serious.

Avoid rock outcroppings, steep convexities and anywhere the snowpack feels thinner than average.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Dec 29th, 2013 2:00PM