Avalanche Forecast

Archived

Feb 12th, 2024–Feb 13th, 2024

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

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

A few more centimeters of snow Monday night may be the last for a while, get ready to soak up some sunshine.

Continue to keep the Persistent and Deep Persistent avalanche problems on your mind, as a couple of recent large natural avalanches have reminded us they are not going away.

Confidence

No Rating

Avalanche Summary

Two recent, and large, Deep Persistent Slab avalanches were observed along the Icefields Parkway on Sunday.

Snowpack Summary

A sun crust has formed on solar aspects up to tree line, and the northwest winds have redistributed the recent snow in open areas at tree line and above.

In sheltered areas 10 - 20 cm of low density snow overlies the Feb 3rd crust, which ranges from 1-3cm thick on shaded aspects up to 2500m, to 15-20cm thick at lower elevations. The Persistent and Deep Persistent weak layers continue to produce whoomphing and sudden fractures in tests.

Weather Summary

Tuesday

A mix of sun and cloud with isolated flurries.

Precipitation: Trace.

Alpine temperature: High -12 °C.

Mostly light ridge wind occasionally gusting to 35 km/h.

Freezing level at valley bottom.

The Mountain Weather Forecast is available at Avalanche Canada https://avalanche.ca/weather/forecast

Terrain and Travel Advice

Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.
Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.

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.

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.