Avalanche Forecast

Archived

Feb 25th, 2024–Feb 26th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural and human triggered avalanches likely.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Regions

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

Big change. Lots of snow and wind have created extensive wind slabs. This is a time to avoid all avalanche terrain.

Confidence

Moderate

Avalanche Summary

Visibility was poor to see if any avalanches have happened. But given the winds and snow that has fallen so far, avalanches should be expected to run to valley bottom.

Snowpack Summary

Lots of new snow and lots of wind is the recipe for fresh reactive slab avalanches. Expect to find 25-45cm of storm snow that has been greatly affected by strong westerly winds.

This storm snow has created fresh wind slabs up to 50cm thick, especially in lee features and cross loaded gullies. These reactive slabs overly a variety of surfaces of concern:

The most recent surface before the storm (February 24) which is a combination of crusts on solar aspects and faceted snow from the last 3 week drought. This is true at all elevations.
The buried rain crust which everyone is calling the February 2 crust that would be down about 50cm. This is also true at all elevations.

It is definitely a time to be conservative in terrain selection.

Weather Summary

15cm of snow has fallen so far on Sunday in the alpine and another 15-20cm is forecast to fall by Monday morning. The winds will be strong out of the West during the snowfall and become light from the West by Monday morning. Temperature on Monday in the alpine is forecast to be a high of -13c. Expect flurries for the remainder of the week.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
Be carefull with sluffing in steep terrain, especially above cliffs and terrain traps.

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.

Loose Dry

Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.