Avalanche Forecast

Archived

Mar 30th, 2023–Mar 31st, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches unlikely, human triggered possible.

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.

Cooler snowy weather is coming for this weekend. The Deep Persistent Slab problem is still a major concern when travelling. Conservative route finding is advised.

Confidence

Moderate

Avalanche Summary

No avalanches have been reported today. But in the last three days, there have been two size 3 natural avalanches and one skier triggered on Miner's Gully. Check out this MIN for photos of the skier-triggered slide in Miner's Gully,

Snowpack Summary

Approximately 25cm of settled snow remains dry on polar aspects and has seen little wind effect. Expect some wind effect starting on Friday with forecast winds. However, solar aspects have now seen several generations of sun crust, and will likely be moist when the sun comes out.

Forecasters are tracking 3 main weak layers in the snowpack. First, a buried sun crust on solar aspects, or a layer of facets on polar aspects, are producing some natural and human-triggered avalanches down between 20 and 40cm. Second, a weak layer of facets buried back in late January has occasionally been active down 80 to 100cm. A very large human-triggered avalanche occurred on this layer late last week. And finally, the basal weaknesses remain. Deep persistent slab avalanches are still possible, especially in shallow snowpack areas. This deep layer may also be prone to "waking up" as slopes start to get more significant solar input. Forecasters continue to have zero confidence in larger terrain features, and we continue to avoid significant overhead terrain.

Weather Summary

Friday will be a mix of sun and cloud until the flurries begin near noon with temperatures between -8c and -3c. Winds are forecast to increase throughout the day from light to strong out of the SW.

Saturday and Sunday: Cooler with snow accumulation of 10-20cm by Sunday night

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Minimize exposure to sun-exposed slopes when the solar radiation is strong.

Problems

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.

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.