Avalanche Forecast

Archived

Mar 3rd, 2024–Mar 5th, 2024

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 possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

The SPAW has been extended until March 7. Wind slab development will stress our persistent and deep persistent problems. Keep it conservative and avoid overhead hazard.

Confidence

Moderate

Avalanche Summary

A widespread avalanche cycle occurred last week as a result of the Feb 29th storm. Natural avalanches up to size 3.5 have been observed in the Icefields/Parker Zone on all aspects in the alpine and the tree line running to the end of avalanche paths. Likewise avalanche control along the Icefields Parkway on Friday had several sympathetic avalanche releases from a single explosion.

No new avalanche activity observed on the Icefields Parkway or Malign Lake Road today.

Snowpack Summary

Up to 50 cm of new snow fell during last weeks storm with strong winds, creating wind slabs. Wind slabs sit over a layer of faceted snow above a 1-3cm thick crust that is down 35-60 cm. The mid-pack is faceted with basal depth hoar and well developed facets near ground. HS ranges from 80 to 140cm.

Weather Summary

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

The next three days will be cold with a mix of sun and cloud. Trace amounts of snow on Tuesday. Temps between -15 and -24°C. Ridge wind West 10 -30 km/h.

Terrain and Travel Advice

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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.