Avalanche Forecast

Archived

Jan 3rd, 2023–Jan 4th, 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, human triggered possible.

Regions

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

Natural avalanche activity has tapered off but human triggering of our persistent and deep persistent slab problems remains possible. Conservative terrain choices and group management recommended for the foreseeable future. Please see this MCR for a more detailed description of conditions down south.

Confidence

Moderate

Avalanche Summary

One size 2 persistent slab was observed Monday across from the Stutfield viewpoint initiating in extreme terrain and scrubbing to ground. Explosive control at Marmot ski area continues to produce avalanches stepping to the basal facets in the alpine including a size 2.5 on Sunday. Last weeks explosive control along the Icefields Parkway produced several large persistent slab avalanches in wind loaded tree line slopes also 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 continue to dominate the forecast through the end of the week. Clear skies on Wednesday with light southwest winds. The ridge will weaken slightly on Thursday bringing increasing cloud; light precipitation is possible over the weekend. Temperatures will be seasonal with a slight warming trend into the weekend.

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.