Avalanche Forecast

Archived

Jan 1st, 2023–Jan 2nd, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

Jasper, Brazeau, Churchill, Cirrus-Wilson, Fryatt, Icefields, Maligne, Marmot, Miette Lake, Pyramid.

Happy New Year! The deep weak layer has potential to be human-triggered on large, steep, convex unsupported terrain. A special avalanche warning has been issued which includes our region. Once the warning expires, it is critical to consider that the deep weak layer will linger for sometime. Don't let it surprise you especially after nothing has happened for a while.

Confidence

Moderate

Avalanche Summary

There was no field patrol on Saturday or Sunday. Wednesday and Thursday's explosive control on some low targets along the Icefields Parkway produced several large slab avalanches in wind loaded tree line slopes. They triggered as the persistent slab and stepped down to the ground. In addition, below tree line slopes produced small slab avalanches. Numerous natural avalanches up to size 2.5 were also observed in the alpine along the Icefields Parkway on these same days.

Snowpack Summary

20-30 cm of surface snow has developed into a persistent slab over the December 17th facets. Alpine and tree line slopes are heavily wind affected. Facets and depth hoar make a weak base in most areas. Snow height ranges from 50-120cm.

Weather Summary

Monday will have clouds, sun, light winds, and -3 °C. Tuesday will be very similar to Monday. Wednesday will be clouds, sunny periods, and cooler temperatures at -11 °C. Thursday will warm up to -6 °C with light winds and clouds.

Terrain and Travel Advice

Make conservative terrain choices and avoid overhead hazard.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.