Avalanche Forecast

Archived

Jan 2nd, 2023–Jan 3rd, 2023

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.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Although natural avalanche activity has decreased and the special avalanche warning has expired, the snowpack remains inherently weak. Human triggering of large deep persistent slab avalanches remains possible.

Confidence

Moderate

Avalanche Summary

One size 2 persistent slab was observed Monday across from the Stutfield viewpoint initiating in extreme terrain and scrubbed to ground. Marmot ski area reporting an explosive controlled size 2.5 persistent slab stepping to ground on Sunday. Last weeks explosive control along the Icefields Parkway produced several large persistent slab avalanches in wind loaded tree line slopes stepping down to our basal weakness. Numerous natural avalanches up to size 2.5 in the alpine and a few thinner slabs below tree line were also observed 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 and variable with many exposed features scrubbed down to ground. The mid and lower snowpack is heavily faceted with depth hoar continuing to develop at the base. Snow height ranges from 50-120cm.

Weather Summary

A surface ridge of high pressure will dominate the forecast through the end of the week. Light cloud and light southwesterly winds are expected Tuesday and Wednesday with seasonal temperatures. No precipitation is forecast.

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.