Avalanche Forecast

Issued: Dec 6th, 2012 10:00AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Fair - Due to variable snowpack conditions

Weather Forecast

Overnight and Friday: Light snowfall (w/ locally moderate accumulations) / moderate west winds / Freezing level at surfaceSaturday: No precipitation / Light northwest winds / Freezing level at surfaceSunday: Light snowfall / Light southwest winds / Freezing level at surface

Avalanche Summary

Observations in the region have been limited; however, on Thursday explosives control produced avalanches to size 1.5 that ran within recent storm layers. There was also an isolated size 1.5 release that failed to ground in steep, unskiable, rocky terrain with crown depths to 85cm.

Snowpack Summary

In the upper snowpack, recent strong winds and light to locally moderate snowfall are responsible for wind slabs which are likely to exist on north to northeast aspects at treeline and above. Winds have also shaped new cornices which could fail and act as a trigger for the slope below.Up to 75cm of  snow that fell over the past week may sit above a surface hoar layer that was buried on November 28th. Although not widespread in the region, releases on this layer may be likely if you have it in your area. Another surface hoar layer that developed during mid-november may exist up to 100cm down, and is still on the radar of professionals in the Golden area.Near the ground is the early November crust. There are some facets below it, or it may appear as a sandwich of crusts and facets. In some areas it may only now be primed for triggering with recent heavy loading. Observations have been limited; however, deep and destructive slides have been reported on this layer in a neighboring region.In general, significant variations in snowpack structure exist across the region. Digging down and making your own observations will be critical to safe slope selection.

Problems

Wind Slabs

An icon showing Wind Slabs
Recent strong winds and snowfall are responsible for widespread windslab development. With higher wind values, loading may have occurred lower on the slope than normal.
Be cautious as you transition into wind affected terrain.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
Two buried spotty surface hoar layers exist up to a metre down and seem to be most reactive in deeper snowpack areas. Where it they exist, slopes may be primed for human triggering.
Be aware of the potential for large avalanches due to the presence of buried surface hoar.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
Recent heavy loading means that deep persistent slabs may only now be primed for triggering. Deep and destructive slides have been reported on this layer in a neighboring region.
Avoid exposure to overhead avalanche terrain, as large avalanches may reach the end of runout zones.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 6

Valid until: Dec 7th, 2012 2:00PM

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