Avalanche Forecast

Archived

Mar 5th, 2024–Mar 6th, 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

Kananaskis, Bow Valley, Highwood Pass, North 40, Spray - KLakes.

The natural avalanche cycle is tapering somewhat, but human-triggering is primed. Very conservative route selection is strongly advised. Also, be mindful of the powerful March solar input, which could initiate slides on solar aspects. The Canmore hill remains closed for at least one more day while clean up crews work on clearing avalanche debris and plowing the road.

A Special Public Avalanche Warning is in effect and has been extended. Click the red SPAW link for details.

Confidence

High

Avalanche Summary

Continued evidence of a widespread naturally triggered avalanche cycle up to size 3.0. Fracture lines are averaging 100cm deep and slides are running far and fast.

Snowpack Summary

A few more cm's in the past 24hrs. Wind slabs are encountered, especially in Alpine areas, on various aspects due to variable winds. These slabs are sensitive to human triggering, and if initiated will likely step down to the Feb 2 layer (facets over a crust) buried 70 to 100cm. The Feb 2 layer has been very active in recent days with a natural avalanche cycle ongoing up to size 3.0. The November basal facets are alive and well and back on our radar as the Feb 2 rain crust is deteriorating and not locking in the weaknesses below it as it once did. Skier weight has now been able to break through the rain crust in some places, which means that the basal facets can now be more easily affected.

Weather Summary

Mostly sunny with light NW winds. Temperatures should reach -10C. No precipitation is expected.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Remote triggering is a concern, watch out for adjacent and overhead slopes.
If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

Problems

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.

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.

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.