Avalanche Forecast

Archived

Apr 5th, 2023–Apr 6th, 2023

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

The sun will be the biggest factor in tomorrow's avalanche hazard. As the temperatures rise, expect the snowpack to loosen up and become more sensitive to triggering. Loose wet avalanches and cornice falls could be in the cards if the sun exposure is strong enough.

Confidence

Moderate

Avalanche Summary

Nothing new was reported or observed today.

Snowpack Summary

Despite the relatively cool temperatures, the snowpack is settling slowly. Recent snowfalls remain dry and largely not effected by wind on polar aspects. On the solar side, surface conditions are turning moist and then re-freezing overnight. However, the snowpack has not yet transitioned to a true "spring" snowpack. Several persistent weak layers remain in the upper and mid snowpack down anywhere from 20 to 80cm. It's worth taking the time to dig down and explore these interfaces as they are highly variable depending on aspect and elevation. Slab avalanches on these interfaces are still possible. And of course, our friendly neighbourhood facet / depth hoar basal layers are still here. These are of more concern in steep, shallow and/or rocky terrain where full-depth avalanches are possible. The strength of the April sun is a factor in "waking up" this deep instability.

Weather Summary

It's looking like tomorrow will be clear to start with some light cloud building during the day. Basically the same convective weather we've seen for awhile now. Morning low of -13, high of -1. Gusty winds, but still light overall. Freezing level of 2100-2200m.

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.