Avalanche Forecast

Archived

Mar 29th, 2024–Mar 31st, 2024

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.

Convective snow is adding up at treeline. Avalanche Danger is rated as Moderate but the snowpack this season is one not to be trusted due to its complex series of crusts and shallow areas. When the snowpack is complex, look for terrain that isn't. Northen aspects are giving the best ski quality.

Confidence

High

Avalanche Summary

A few loose dry avalanches have been observed over the past 24hrs from steep unskiable terrain.

Snowpack Summary

Up to 20cm of snow has fallen at treeline over the past 24hrs and another 5-10cm is forecast overnight. This new snow is overlying a variety of surfaces from temperature crusts on solar aspects to dry snow on polar aspects. Winds have been in to 20-30km/hr range out of the SW so we have seen some windslab development in the alpine and isolated areas at treeline. Evaluate the bond with the new snow and the underlying crust before committing into a feature. While we have seen the February crust become less reactive its still a concern and worth a dig to see what its doing. Thin weak areas have also been the cause of at least one skier sz 3 accidental avalanche that triggered the deep persistent slab layers near ground. Forecasters have low confidence in any features that have not slid yet this season. Moderate danger means Human triggered avalanches are possible.

When the sun comes out and temperatures warm up, expect avalanche danger to increase. Especially on solar aspects in thin steep rocky terrain. Start early these days and be done early before the heat arrives. Plan your tour to avoid solar aspects later in the day and think about slopes in the sun first thing in the morning when you are in the cool valley floor.

Weather Summary

An additional 5-10cm of snow is forecast overnight with continued light winds out of the west. The sky will be a mix of sun and cloud with temperatures around -4C. Be aware that when the sun comes out it packs a punch! Stability will quickly deteriorate on solar aspects when the sun comes out. These effects will me most apparent in thin rocky terrain so be sure to think about aspect at this time of year as well as time of day.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Conditions may have improved, but be mindful that deep instabilities are still present.
Recent wind has varied in direction so watch for wind slabs on all aspects.
The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet

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.