Avalanche Forecast

Issued: Dec 1st, 2012 8:48AM

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 low pressure center off the BC coast and a steady southwesterly flow over the province will maintain mild temperatures and moderate precipitation for the next few days.Sunday: Moderate snowfall – 10-20 cm, the freezing level is around 1000-1200 m, winds are moderate to strong from the south. Monday: Moderate snowfall – 10-15 cm, the freezing level is around 1000 m, winds are light to moderate from the southwest. Tuesday: Moderate to locally heavy precipitation, the freezing level should jump to 1800 m.

Avalanche Summary

Several natural and skier triggered avalanches up to size 1.5 were reported in the Kootenay Pass area on Friday. Most of these avalanches were 25-30 cm deep and were probably releasing on a surface hoar layer or crust. The size and likelihood of natural and human triggering avalanches will increase with continued precipitation over the next few days. If you and your friends have been out exploring and riding in the backcountry and have some observations to share please send an email to forecaster@avalanche.ca.

Snowpack Summary

An additional 20-30 cm of heavy new snow has fallen in the past 24 hours. This dense storm snow sits on a crust and/or surface hoar layer, now down 40-50 cm. Recent snowpack tests give consistent easy results on this layer. Given the current weather forecast I would suspect that this layer will be primed for natural and human triggered avalanches for the next few days.In the mid snowpack, there may be a spotty and thin buried surface hoar layer between 50 and 80cm deep. At the base of the snowpack sits the early November rain crust. Located about 100cm below the surface, it seems most likely to be found in deeper snowpack areas and may have associated facets. These layers seem to have been unreactive in recent days, but may have the potential to 'wake-up' with additional loading.In general, snowpack data is sparse in this region and significant variations likely exist from one drainage to another. In short, digging down and making your own observations will be critical to safe slope selection.

Problems

Storm Slabs

An icon showing Storm Slabs
Continued snow and wind may overload a weak layer of surface hoar and/or a crust, now down 40-50 cm. The size and likelihood of avalanches should increase throughout the forecast period.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Stick to simple terrain and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Although the likelihood of triggering this layer is low, the consequences could be very serious. This layer may wake-up with additional loading.
Be aware of thin areas that may propagate to deeper instabilites.>Whumpfing is direct evidence of a buried instability.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 2nd, 2012 2:00PM