Avalanche Forecast

Archived

Feb 29th, 2024–Mar 1st, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

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 storm may be over but the avalanche cycle is not. Avoid avalanche terrain for the time being.

The Icefields Parkway and Maligne Lake Road remain CLOSED for avalanche hazard and control. Check Alberta 511 for updates.

Confidence

Moderate

Avalanche Summary

The widespread natural avalanche cycle is expected to continue following the recent storm.

The previous storm on Feb 24-25 produced widespread natural avalanches, size 2-3 windslab and storm slab, sliding on the Feb. 3rd crust and occasionally stepping down to ground. Explosives control produced numerous size 2 windslabs,

Snowpack Summary

Up to 50 cm of new snow fell in this storm with strong south and southwest winds, creating widespread windslab. This storms snow is now sitting on 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 130cm.

Weather Summary

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

Friday

Cloudy with sunny periods and isolated flurries. Alpine temperature High, -11 °C. Ridge wind south, 10-25 km/h.

Saturday

Cloudy with scattered flurries (4 cm). Alpine temperature: Low -22 °C, High -14 °C. Ridge wind east, 10 km/h.

Terrain and Travel Advice

Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time.
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.