Avalanche Forecast

Issued: Dec 28th, 2015 8:10AM

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

Avalanche Canada jlammers, Avalanche Canada

Touchy avalanche conditions are expected to persist. If you have questions about the snowpack, conservative terrain selection is always the answer.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

A ridge of high pressure has set up over the province and will bring mainly clear skies for the forecast period. Ridgetop winds should remain light and northwesterly on Tuesday and Wednesday. Winds will switch to southwesterly on Thursday intensifying throughout the day. Alpine temperatures should sit at about -10 on Tuesday and Wednesday with an inversion developing on Thursday.

Avalanche Summary

Evidence of natural storm slab avalanches to size 2 was observed in the wake of Saturday's storm. In sheltered terrain, loose dry avalanche activity has also been noted. Natural avalanche activity will likely taper-off with the current clearing trend. However, human-triggered avalanches will remain a concern for the forecast period, especially at elevations or in parts of the region where recent storm accumulations have settled into a cohesive slab.

Snowpack Summary

Last weekend, between 25cm and 40cm of new snow fell. Winds associated with the storm were highly variable. In areas (or at elevations) where the wind was strong, there may be a cohesive and reactive storm slab. In areas where the winds were light, you're more likely to find loose powder. The new snow overlies a touchy layer of sugary faceted snow and well-developed surface hoar which is reported to exist on all aspects and elevations. Due to the persistent nature of these underlying crystals, newly formed storm slabs may remain reactive for the foreseeable future. Adding to the mix of weaknesses in the upper snowpack are a few other surface hoar layers that developed throughout December which you may now find buried in the top 100cm. The weight of the new snow (or a surface avalanche in motion) may cause these layers to "wake up" resulting in larger, more destructive avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 40cm of recent storm snow overlies a weak mix of facets and surface hoar. I'd be extra cautious in wind-affected areas where the new snow exists as a cohesive slab. Touchy conditions should persist for the forecast period.
Be alert to conditions that change with elevation.>Be cautious as you transition into wind affected terrain.>The new snow will require several days to settle and stabilize.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
A few buried surface hoar layers exist in the top 100cm of the snowpack. I would keep these on my radar on steep unsupported slopes, especially at treeline and below.
Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 29th, 2015 2:00PM