Avalanche Forecast

Archived

Jan 31st, 2023–Feb 1st, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

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.

Incremental new snow with moderate southwest winds will continue to build wind slabs and add stress to the deep persistent problem. Continue to be patient and conservative in your terrain choices.

Confidence

Moderate

Avalanche Summary

Highway 93 patrol on Sunday noted isolated wind slab activity to size 1.5 and several deep persistent slab avalanches up to size 2.5 in the alpine on southerly aspects likely occurring Friday and Saturday.

Of note is how sensitive the deep persistent problem is to additional load i.e. 10mm of precipitation with wind was enough to initiate a significant cycle on this layer January 27 and 28th.

Don't forget to post avalanche observations to the MIN.

Snowpack Summary

5cm Monday morning adding to the up to 20cm of settled new snow during the past week. Previous moderate to strong northerly winds and present moderate southwesterly winds have added to variable wind slab development in the alpine and exposed tree line. Generally, the bottom of the snowpack is weak facets and depth hoar. The snowpack ranges from 50 to 120cm.

Weather Summary

A series of low pressure systems and troughs will bring isolated to light precipitation through the remainder of the week. Up to 5mm is possible by Friday. Temperatures will be seasonal trending milder on Thursday. Winds will be consistent light to moderate values from the southwest.

Detailed weather forecasts from Avalanche Canada: https://avalanche.ca/weather/forecast

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Recent wind has varied in direction so watch for wind slabs on all aspects.

Problems

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.

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.