Avalanche Forecast

Issued: Dec 26th, 2015 4:00PM

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

jonas hoke, Parks Canada

Waterton Lakes.

Mid winter conditions make for great skiing in many locations, but also makes for an increasingly complex snowpack. Evaluate the conditions carefully before committing to big terrain.

Summary

Weather Forecast

A ridge of high pressure will remain over the area until Sunday evening, a gradual rise in temperatures will be accompanied by moderate - strong Westerly winds. On Monday this ridge breaks down and a SW flow brings snow, with accumulations of up to 5cm. Tuesday the flow switches to NE, temperatures drop, and we may see a further 5cm of snow.

Snowpack Summary

Up to 55cm of low density snow has fallen since Dec 20 and is now being redistributed into wind slabs by gusty Moderate W winds. This overlies variable layers of old windslab with the Dec 9th crust below(down 50-90cm), which remains a concern as a potential weak interface, especially with cold temps promoting facetting of the snow above and below.

Avalanche Summary

Several size 1 loose snow avalanches were observed yesterday, likely triggered by the snowfall on Christmas eve.

Confidence

Timing, track, or intensity of incoming weather system is uncertain

Problems

Wind Slabs

Watch for new wind slab development with ongoing Moderate to Strong Westerly winds. Fresh windslabs may become buried with light snowfall later in the forecast period.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

Wind effect will make this problem less widespread, however sluffing will remain a concern in steep sheltered terrain

Be cautious of sluffing in steep terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

A large natural slab avalanche was observed last wednesday, this may have released at a buried crust from early December. For now, it is unclear if this will remain an isolated event, or if this layer is becoming more sensitive to loads.

Dig down to find and test weak layers before committing to a line.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely

Expected Size

1 - 3

Valid until: Dec 29th, 2015 4:00PM