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Avalanche Forecast

Archived

Mar 15th, 2024–Mar 16th, 2024

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

Banff Yoho Kootenay, Little Yoho, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

A significant warmup and an already unreliable snowpack provide the ingredients for an avalanche cycle. Without a significant re-freeze Friday night, the danger will rise quickly, especially on solar aspects.

Through these fluctuating conditions, we will list the highest expected rating of the day.

Confidence

High

Avalanche Summary

The avalanche cycle continued this afternoon with ski hill's reporting numerous avalanches up to size 3. An avalanche was reported to have run over Man Yoga (mixed climb), likely size 2 on the Stanley Headwall with additional natural activity in that area. The avalanches reported have been solar triggered.

If the lack of a refreeze materializes, we will see continued activity tomorrow.

The photos below are from yesterday afternoon's avalanche cycle.

Snowpack Summary

Moist snow formed today up to 2500m on all aspects and as high as 2900m on solar aspects. If the inversion materializes we may not have crusts from treeline up to the alpine, but they will be present BTL. Only the highest north aspects will have dry snow. 50-90 cm of settled snow overlies weaker facets above the Feb 3 crust interface, up to at least 2500 m. The base of the snowpack consists of weak facets. Deeper snowpack areas (west of the divide) are more settled and stronger.

Weather Summary

Friday night: Valley bottom freezing levels except for an above-freezing layer from 2300m to the alpine (aka no freeze!).

Saturday: 3000m+ freezing levels (high +8C at treeline), with light winds and sunny skies. Valley bottoms are forecast to hit +13C.

Sunday: Much the same, maybe warmer. +15C valley bottom and 3200m freezing levels.

For more details on the weather, click here.

Terrain and Travel Advice

  • Be alert to conditions that change with aspect and elevation.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.

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.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.