Avalanche Forecast

Issued: Dec 22nd, 2018 4:00PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

The weak layers in the snowpack are unlikely to stabilize quickly. Human triggered avalanches are likely for a while yet. Make conservative terrain choices.

Summary

Weather Forecast

Cold (mid teens) and cloudy. Conditions are unlikely to have much effect on the forecast.

Snowpack Summary

An average 40-80 of recent storm snow with variable wind effect now sits over the Dec. 10 facet/surface hoar interface. In many areas the lower snowpack is weak with the October 26 depth hoar, facets and crust near the base. Snow pack depths range from 90-160 cm at ~2000 m.

Avalanche Summary

The natural cycle continued into this morning throughout the forecast area. Large avalanches to size 3 were noted.

Confidence

Problems

Deep Persistent Slabs

Recent snow has now overloaded the Oct. 26 deep persistent layer of facets and depth hoar, and there is enough mass now to cause large avalanches.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3

Persistent Slabs

The Dec. 10 persistent layer of facets and surface hoar is now buried 40 - 80cm. Avalanches have either been independently running on this layer, or stepping down to the basal weakness.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2.5

Wind Slabs

Fresh wind slabs from strong winds over the last 2 days have formed within the new storm snow. These will be most prevalent in the lee of features and may stay reactive over the next couple of days.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 23rd, 2018 4:00PM