Avalanche Forecast

Archived

Jan 30th, 2023–Jan 31st, 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.

The weak base of our snowpack will persist even when the signs indicate an improving trend. Maintain your discipline to not push into bigger terrain.

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.

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

Snowpack Summary

10 to 20cm of soft settled new snow from Jan 27th overlies a weak melt-freeze crust up to 2000m. Wind slabs are present in the alpine and exposed tree line locations. Generally, the bottom of the snowpack is weak facets and depth hoar. The snowpack ranges from 50 to 120cm.

Weather Summary

Transitioning from cold Arctic air back to a westerly flow. Tuesday a series of weak low pressure systems and troughs will bring isolated to light precipitation through the remainder of the week. Up to 10mm is possible by Friday. Temperatures will be seasonal trending milder towards the weekend. Winds will be consistent light to moderate values from the west.

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.