Avalanche Forecast

Archived

Feb 20th, 2024–Feb 21st, 2024

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.

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.

Be on the lookout for wind slab development throughout the week and avoid shallow areas where the February 3rd crust is starting to deteriorate.

Confidence

Moderate

Avalanche Summary

No new avalanche activity reported on the Icefields Parkway or Maligne Lake Road today.

Snowpack Summary

A dusting of new snow sits over a sun crust on solar aspects. The Feb 3rd crust is down 15-30cm and is 1-3cm thick in the alpine. On shaded aspects, the Feb 3rd crust exists up to 2500m and it is starting to break down. On solar aspects this crust extends up to 2800m and it is 15-20cm thick at lower elevations. The Persistent and Deep Persistent weak layers continue to produce whoomphing and sudden fractures in tests.

Weather Summary

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

Stable weather for the next three days. Mainly cloudy with isolated flurries and trace precipitation. Alpine temperature from -4 to -10°C. Ridge wind SW 10-25 km/h Wednesday and Thursday with gusts up to 45km/h on Friday. Freezing level 1800m on Wednesday dropping to valley bottom by Friday.

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.