Avalanche Forecast

Archived

Dec 27th, 2022–Dec 28th, 2022

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

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.

Up to 30 cm of new snow since Dec 23rd with strong winds and warm temperatures will test the snowpack the next few days. Be mindful of these changes and choose your ski lines conservatively. Highway 93 is closed for explosive control work until Wednesday evening. Check AB511 for live updates on road closures.

Confidence

Moderate

Avalanche Summary

Tuesday's Icefield patrol noted one size 2.5 in the alpine sliding on the deep persistent problem. There was no Icefield patrol on Monday but snowballing was observed at low elevation along Maligne road. Sunday's Icefield patrol noted a few small loose dry avalanches below tree line. Marmot Basin reported several small stiff wind slab avalanches with good propagation on Sunday.

Snowpack Summary

Approximately 20-30 cm of snow has accumulated since December 23rd. It is over a generally faceted snowpack. Depth hoar and well developed Facets can be located near the ground particularly in shallow locations. Strong southwesterly winds from a couple days ago created hard wind slabs in the alpine and exposed tree line locations. Snow height ranges from 50-120cm.

Weather Summary

Tuesday night will be clouds, clear periods, isolated flurries, -6 °C, and light Southwest winds. Wednesday will be cloudy with sunny periods and isolated flurries, -5 °C, and light Southwest winds. Thursday and Friday will be similar yet slightly cooler temperatures.

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

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.