Avalanche Forecast

Issued: Jan 12th, 2019 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 and Wind Slabs.

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

The weak Oct.26 basal depth hoar and facets are not going to magically go away. Its going to be a long waiting game for good conditions in bigger terrain and we are not there yet. Good ski quality exists in sheltered areas.

Summary

Weather Forecast

Inverted temperatures will persist for the next couple days with 3000m temperatures in the -5 to -2C range and valley bottom temperatures much cooler (-10 to -15C). Winds will be light to moderate from the SW Sunday.

Snowpack Summary

Snowfall since Jan2 has been redistributed by southwest winds yielding extensive wind effect in the alpine. In thick snowpack areas, the Dec 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, there is little separation between Dec 10 and the weak depth hoar/ facets sitting 40 cm above the ground.

Avalanche Summary

Natural activity noted on Fatigue Mountain and Mount Ball up to size 3 today, both deep persistent slides scrubbing to ground. We have had observations like this every day for a week. Explosive control today at ski hills in previously controlled terrain produced minimal results,and reports were that the wind slabs were less reactive than yesterday.

Confidence

Problems

Deep Persistent Slabs

The facets and depth hoar 40 cm above the ground inspire little confidence. Some large natural avalanches are still occurring and human triggering is likely. This layer needs time to adjust to the load and this problem will be around for some time.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.Be aware of the potential for wide propagations which could result in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3.5

Wind Slabs

These wind slabs are becoming less reactive but should be treated with respect if encountered. If initiated these slabs could provide enough load to trigger the deeper basal layers.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 13th, 2019 4:00PM