Avalanche Forecast

Archived

Mar 6th, 2024–Mar 7th, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Regions

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

Solar input will increase the reactivity of wind slabs and persistent slabs. Human-triggered and remote-triggered avalanches remain likely.

Confidence

Moderate

Avalanche Summary

A widespread avalanche cycle occurred last week as a result of the Feb 29th storm. Natural avalanches upto size 3.5 have been observed on the Icefields Parkway - all aspects in the alpine & at tree line running to the end of avalanche paths. 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 over the past 3 days.

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. This persistent weak layer is consistently reactive in snowpit tests and is not going away anytime soon. The mid-pack is faceted with basal depth hoar and well developed facets near ground. HS ranges from 80 to 150cm.

Weather Summary

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

Thursday Mix of sun and cloud. Alpine High -10 °C. Wind 15 km/h

Friday Cloudy with sunny periods & isolated flurries. Trace precipitation. Alpine High -7. Wind SW 20 km/h

Saturday Cloudy with sunny periods & isolated flurries. Accumulation 4 cm. Alpine high -3. Wind W 20 km/h gusting to 60. Freezing level 1800m

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.