Avalanche Forecast

Issued: Dec 2nd, 2012 8:32AM

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

Avalanche Canada Peter, Avalanche Canada

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

Synopsis: A broad and persistent trough of low pressure of the coast of BC will maintain a westerly-southwesterly flow with mild and wet conditions for the next few days. A strong frontal system should move across southern BC on Tuesday bringing heavier precipitation and rising freezing levels. Monday: Light to moderate snowfall – 10-15 cm; the freezing level is around 1000 m; winds are light to moderate from the southwest. Tuesday: Heavy snow – 25-35 cm; the freezing level could jump to 1600 m; winds are strong from the southwest. Wednesday: Cloudy with flurries; the freezing level lowers to near valley bottom.

Avalanche Summary

A widespread natural avalanche cycle was reported in parts of the region on Saturday. Avalanches up to size 2 were observed, mainly involving the recent storm snow and likely failing on the late November surface hoar layer.

Snowpack Summary

Up to 70 cm of moist storm snow has fallen in the past 3 days. This snowfall was accompanied by generally moderate southerly winds, forming wind slabs in exposed leeward terrain. Below the storm snow is a layer of surface hoar or a thin crust. There are no new snowpack tests on this layer, but it is likely that this layer is primed for natural and skier triggered avalanches.Deeper in the snowpack you might find a thin, spotty surface hoar layer about 100cm down. As well, the early November rain crust now sits over 120cm down in most locations (at treeline and above) and may exist in combination with facets. These layers seem to have been unreactive in recent days, but may have the potential to 'wake-up' with continued loading and forecast warming. There is also the potential for storm slabs to "step down" creating a very large and destructive avalanche.

Problems

Storm Slabs

An icon showing Storm Slabs
Up to 70 cm of dense and moist storm snow has fallen in the past few days. This storm snow may be sitting on a weak layer of surface hoar or a thin crust, and may release naturally or by the weight of a person.
Stick to simple terrain and be aware of what is above you at all times.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 6

Persistent Slabs

An icon showing Persistent Slabs
Deeper persistent weak layers may wake up with continued loading and forecast warming. Storm slabs may also "step down" to these weaknesses, creating a very large and destructive avalanche.
Carefully evaluate and use caution around thin snowpack areas.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Dec 3rd, 2012 2:00PM