Avalanche Forecast

Archived

Mar 21st, 2023–Mar 22nd, 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 possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Wednesday is calling for +8 in Canmore, and sunny skies. Consider your over head (solar slopes and cornices) when you are traveling throughout the day. Perfect sunny touring weather at the moment!

Confidence

Moderate

Avalanche Summary

A road patrol today down the spray road noted no new avalanches, However there is good evidence of slabs pulling out over the last week. On solar slopes along the road, pinwheeling is starting to be observed,

Snowpack Summary

The fresh snow from last week has largely escaped the wind.....so far. Many areas still have soft snow, but expect sun crusts on solar aspects at all elevations where the terrain is steeper than about 20 degrees. The strong late March sun is melting these surface crusts and destabilizing the slopes. There are previously formed wind slabs in alpine areas, so keep an eye out for these in lee and cross-loaded features. The midpack remains highly variable with areas of more than 100cm of total snowpack being supportive, but in shallower areas ski penetration can still be to ground. The good old facets and depth hoar still lurk at the bottom of the snowpack and present an ongoing concern for full-depth avalanches. Expect the avalanche hazard to deteriorate throughout the day with the solar input and rising freezing level. This will be of greatest concern under larger features where the solar radiation could trigger the deep persistent layer.

Weather Summary

Wednesday: SUNNY, high of -3 with 15km/h west winds. Freezing levels will rise to 2200m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Cornices become weak with daytime heating or solar exposure.

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.