Avalanche Forecast

Archived

Apr 1st, 2024–Apr 2nd, 2024

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

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.

Excellent dry snow can still be found on North to Northeast aspects. The Danger Level on Tuesday will depend greatly on sky conditions (sunny with lots of solar input, or cloudy) and the quality of the overnight freeze. Freezing levels are excepted to be near 2600m, so the strategy of an early start and early finish is likely a good one. Time to start employing a Spring ski touring mindset.

Confidence

Moderate

Avalanche Summary

Isolated loose dry from extreme Alpine terrain up to size 1.5, likely triggered by solar input. One size 2.5 naturally triggered wind slab occurred within the last 24hrs on a steep N/NE aspect in the Alpine. The debris from this slide ran well below treeline into previously skied terrain.

Snowpack Summary

Previous storm snow totals of up to 60cm are now settling due to mild temps and intense solar radiation. Crusts are found on all solar aspects, which are then melting through the day. True north aspects remain dry to valley floor. Isolated wind slabs are found in the Alpine, especially in lee and cross-loaded features. The March 20 crust down 40 to 60cm is giving resistant shears. While we have seen the February crust become less reactive, it's still a concern and worth a dig to see what it's doing. Thin weak areas have also been the cause of at least one recent size 3.0 skier 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 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

Tuesday will be mainly cloudy with temps climbing to +2C by midday and freezing levels near 2600m. Winds will be strong from the West.

Wednesday will see the start of a precipitation event including rain on Wednesday and snow on Thursday.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Conditions may have improved, but be mindful that deep instabilities are still present.
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.