Avalanche Forecast

Issued: Dec 23rd, 2014 8:41AM

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

Avalanche Canada swerner, Avalanche Canada

Avalanche hazard is high. As it decreases over the next few days, conditions will remain very tricky.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

A Pacific frontal system reaches the Interior Tuesday afternoon bringing snow amounts will anywhere from 10-25 cm. This will be accompanied by moderate west ridgetop winds, switching NW by the afternoon. Treeline freezing levels will hover around 1000 m. By Thursday an upper ridge will build behind the cold front bringing cooler conditions with mostly cloudy skies and light snow.

Avalanche Summary

On Monday, numerous natural, skier triggered and remotely triggered avalanches occurred from distances up to 40 m away. Most of these were size 1-2.5, with one avalanche reaching size 3. These avalanches have been failing on a buried surface hoar layer 30-60 cm down, and with new snow and wind in the forecast the slab above this layer will grow thicker. Best case scenario is that the new storm snow will initiate a widespread natural avalanche cycle, however; if it doesn't reach its tipping point then it will likely be primed for rider triggers.

Snowpack Summary

New snow 15-30 cm, accompanied by moderate-strong SW winds will add additional load to the upper snowpack. This brings storm snow totals 40-90 cm above a very touchy surface hoar layer that was buried mid-December. Below 2100 m this storm slab sits on a thick, solid crust that has been reacting as a perfect sliding layer. Storm slabs will blanket the region and be very touchy to the weight of a skier/ rider, especially in locations that has seen wind effect. A hard rain crust with facets from early November is buried over 1 m down and is still reactive to light loads in some locations.

Problems

Storm Slabs

An icon showing Storm Slabs
A thick storm slabs sits over a predominant surface hoar layer which has been very touchy to rider triggers. With additional snow, natural avalanches are likely and human triggered avalanches are very likely.
Avoid avalanche terrain during periods of heavy loading from new snow and wind. >Stick to simple terrain, small features with limited consequence and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The new snow load continues to build and this could reawaken the Nov 9 layer at the bottom of the snowpack. Shallow avalanches running on the surface hoar may also trigger this layer.
Avoid shallow snowpack areas where triggering is more likely.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Dec 24th, 2014 2:00PM