Avalanche Forecast

Archived

Mar 8th, 2024–Mar 9th, 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 and human triggered avalanches likely.

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, Ghost.

We are teetering between Considerable and High in the alpine. Wind and temperature are the factors at play. Watch warming, sun exposure and fresh windloading VERY carefully. Human triggering is a major concern.

The Ghost area is included in the Special Public Avalanche Warning. Warming may trigger windslabs and cornice failure. Avoid overhead terrain.

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

Confidence

High

Avalanche Summary

Less natural activity today. Only a few small pockets that released, likely due to sun exposure.

Snowpack Summary

Winds were stronger than expected today. Lots of transport at ridgetop, and even a few "snow devils" mid slope. Expect windloading to continue tonight. Today, near Tent Ridge we encountered fresh windslabs at 2300m; a full 60m below ridgeline. They were significant enough to call an early end to our day. At treeline, the upper 60-70cm is well settled. Beneath that the deeper layers are the opposite, loose and weak. The Feb 2 crust is continuing to break down and become a weak triggering layer.

Weather Summary

Tomorrow will be much warmer than the last few days. The warm air moved into the area earlier than expected, so expect forecasted highs be a bit less than actual. Tomorrow's predicted high is -2 for 2200m. Skies will be clear enough for the sun to warm the air, and snow. Winds will also pick up, with ridgetop speeds hovering around the 40km/hr mark. No snow for tomorrow, but flurries may start in the evening.

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

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.