Avalanche Forecast

Issued: Dec 23rd, 2018 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

The natural cycle is tapering off, however, the weak layers in the snowpack are still reactive. Don't expect conditions to improve quickly and adjust your terrain decisions accordingly.

Summary

Weather Forecast

Lows in the mid teens are expected over the next few days. High overcast skies will at times produce very light amounts of snow (trace). Winds are dropping and it is expected to be calm on Christmas Day.

Snowpack Summary

An average 40-80 of recent storm snow with variable wind effect now sits over the Dec. 10 facet/surface hoar interface. This layer is producing snowpack test results in the hard range. 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 avalanche cycle has started to taper off with the cooler temperatures. Large avalanches to size 3 have been noted in the last few days.

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.

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 24th, 2018 4:00PM