Avalanche Forecast

Issued: Dec 23rd, 2014 8:21AM

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

percy woods, Parks Canada

Glacier.

We have a reactive surface hoar layer with a 50cm surface slab on top of it. Cooling temperatures and moderate winds will consolidate the surface slab further. Stick to low angle forested terrain. Avoid exposure to overhead hazard.

Summary

Weather Forecast

Upwards of 25cm of storm snow are expected in the next 24hrs along with slightly cooler temps and South through Southwest winds in the low end of moderate.

Snowpack Summary

A building surface slab sits on top of the well preserved and widespread Dec 17th surface hoar layer (10-20mm) down 30 to 60cm depending on wind loading. This SH layer sits on top of a rain crust up to 2100m on well settled snow above 2100m. The Dec 9th surface hoar layer is down 80cm in the area. The Nov 9th crust lurks 30cm up from the ground.

Avalanche Summary

Numerous skier triggered and natural avalanches were observed or reported yesterday. Remote triggering of the surface slab from distances greater than 50m were reported. Most of the activity was occurring between 1700-2400m. One reported skier triggered slide propagated over 200m. This avalanche activity should be expected to continue today.

Confidence

Forecast snowfall amounts are uncertain

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.

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

Aspects: All aspects.

Elevations: All elevations.

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 24th, 2014 8:00AM