Avalanche Forecast

Issued: Dec 22nd, 2014 8:12AM

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

ali haeri, Parks Canada

Glacier.

We have a reactive layer down 50cm and overnight winds that have consolidated the slab further. Stick to forested and low angle terrain if you head in the backcountry. Limit your exposure to overhead hazard.

Summary

Weather Forecast

Snow should be tapering off today as a brief ridge of high pressure builds. Expect cloud and light snow with temperatures remaining steady at around -5 and winds in the 20-40km/h range at 2000m from the west. Pacific frontal system is forecast to hit the interior Tuesday afternoon bringing moderate amounts of snow and heavier into Wednesday.

Snowpack Summary

50cm of recent storm snow sits over the Dec 17 surface hoar, 10-20mm, which sits on or just above a rain crust to 2100m and on settled snow above 2100m. The Dec 9, surface hoar size 3-5mm is visible in certain areas down ~80cm. Mid-pack is well settled with the Nov 9 crust/facet layer in the bottom 30cm.

Avalanche Summary

Field team on Mt Fidelity, 1900m to 2100m, reporting touchy conditions with several skier remote and control triggered size 1.0 and 2 size 2.0 avalanches with wide propagation down 30cm running on the Dec 17 surface hoar/crust layer. Numerous size 2.0 natural slab avalanches observed yesterday east of the Rogers Pass summit in the highway corridor

Confidence

Due to the number and quality of field observations

Problems

Storm Slabs

A 50cm slab sits over a very obvious surface hoar layer that reacted to human triggering yesterday. Sensitivity varies depending on drainage and elevation but the layer was observed to be almost everywhere and is a very real threat to riders.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

2 - 3

Deep Persistent Slabs

The new snow load continues to slowly build and this could reawaken the Nov 9 layer at the bottom of the snowpack. Shallow avalanches running on the surface hoar can also trigger this layer. This will be even more of a concern in the coming days.

Avoid shallow snowpack areas where triggering is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

Valid until: Dec 23rd, 2014 8:00AM