Avalanche Forecast

Issued: Dec 1st, 2012 8:49AM

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 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 light to moderate precipitation for the next few days.Sunday: Light to locally moderate snowfall – 5-10 cm, the freezing level is around 800 m, winds are light from the south. Monday: Light snowfall – 5-10 cm, the freezing level is around 800 m, winds are light to moderate from the southwest. Tuesday: Moderate precipitation, the freezing level should jump to 1200-1400 m.

Avalanche Summary

There was one report late last week of a size 2.5 natural avalanche that likely released on the early November persistent weak layer. There are no other recent observations. We welcome all observations at forecaster@avalanche.ca.

Snowpack Summary

A recently buried surface hoar layer is now down around 30-50 cm. We have limited information on the extent and sensitivity of this layer in this region. Watch for clues of instability like whumpfing or cracking and recent avalanches. There may be another thin buried surface hoar layer down about 115 cm. As well, the November rain crust now exists over 125cm down in some locations and may exist in combination with facets. These layers seems to have been unreactive in recent days, but may have the potential to 'wake-up' with additional loading.Average snow depths at treeline seem to be between 140cm and 170cm. 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. Any observations from the field are welcome at forecaster@avalanche.ca.

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 30-40 cm. The size and likelihood of avalanches should increase throughout the forecast period.
Use ridges or ribs to avoid pockets of wind loaded snow.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Although the likelihood of a release is low, the consequences of a persistent slab release could be significant. These layers may wake-up with additional loading.
Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

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