Avalanche Forecast

Issued: Dec 18th, 2018 4:00PM

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.

ian jackson, Parks Canada

Banff Yoho Kootenay.

More snow is raising the avalanche danger. It is a good time to stay out of backcountry avalanche terrain and shred some pow at your local ski hill!

Summary

Weather Forecast

Two significant frontal systems are lined up to move inland over the next three days. 25-40 cm of additional new snow is expected along the divide by end of day on Thursday. This snow will be accompanied by moderate to strong SW winds. Freezing levels remain at valley bottom. On Friday, temperatures cool with lighter windspeeds and snow amounts

Snowpack Summary

Another 5-10 cm of snow has fallen on Tuesday bringing the total to 50-70 cms sitting on top of the Dec 10th weak layer (facets and surface hoar). Fresh windslabs can be expected on lee (north and east) aspects. The lower snowpack is weak and facetted. Any avalanches initiated in the storm snow have potential to step down to this lower layer.

Avalanche Summary

Numerous natural and skier (or explosive) triggered avalanches up to 2.5 have been reported over the past few days. Avalanches may run further down slope than expected, so be cautious of overhead hazard.

Confidence

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

Problems

Storm Slabs

Another 25-40 cm of new snow is forecast by end of day Thursday. This is falling on 50-70 cm deep storm slabs that have been reactive over the last week. These slabs are sitting on the Dec. 10th layer of facets and surface hoar.

Avoid all avalanche terrain.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

The mid and lower portions of the snowpack are weak and are now overloaded with critical levels of snow. We expect avalanches to step down to this deeper layer, especially in thinner snowpack areas.

Good day to make conservative terrain choices.Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1.5 - 3

Valid until: Dec 19th, 2018 4:00PM