Avalanche Forecast

Issued: Dec 30th, 2015 10:14AM

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

Avalanche Canada jlammers, Avalanche Canada

Recent winds have been highly variable, and so is the reactivity of recent storm snow. Make observations continually as you travel.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

The current ridge of high pressure will persist for the foreseeable future bringing mainly clear skies for the forecast period. Ridgetop winds will intensify throughout the day on Thursday, and remain strong and southwesterly until Saturday. An inversion is forecast for all 3 days with above-freezing temperatures expected in the alpine by Thursday afternoon.

Avalanche Summary

Natural avalanche storm slab activity has tapered-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. Solar-induced loose wet avalanches up to size 1.5 have also been reported. The likelihood and size of loose wet avalanches will increase with warmer alpine temperatures expected during the forecast period.

Snowpack Summary

Between 25 and 40cm of recent storm snow overlies a widespread mix of faceted snow and surface hoar. The nature of the snow surface appears to be quite variable. In areas where recent winds were strong, these recent accumulations may exist as a deep, cohesive and reactive slab. In areas where the winds were light, you're more likely to find loose powder. Solar radiation has also come into play, and depending on the time of day, steep solar aspects may be moist or refrozen.Professionals in the region are still keeping an eye on a few other surface hoar layers that developed throughout December which are now buried in the top 100cm. Although these layers may be gaining some strength, they are worth investigating, especially in steep, unsupported terrain at treeline and below.

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 areas where wind or warming has caused these accumulations to settle into a cohesive slab.
Be alert to conditions that change with elevation.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

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

Loose Wet

An icon showing Loose Wet
Temperature inversions and solar radiation forecast for the next few days will promote loose wet avalanche activity, especially on steep, sun-exposed slopes.
Be alert to conditions that change with aspect, elevation and time of day.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. >

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 31st, 2015 2:00PM