Avalanche Forecast

Archived

Feb 27th, 2024–Feb 28th, 2024

Alpine

Natural and human triggered avalanches likely.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches possible, human triggered probable.

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.

Regions

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

Avoid avalanche terrain as natural avalanche cycle is expected.

THE CANMORE HILL FROM THE NORDIC CENTRE TO GOAT CREEK PARKING LOT WILL BE CLOSED AT 1PM ON WEDNESDAY FEBRUARY 28 FOR AVALANCHE CONTROL.

Confidence

Moderate

Avalanche Summary

Several loose dry avalanches up to size 1 have been observed. Some wind slab avalanches have also been observed up to size 2 in both steep terrain and at treeline. This next storm will likely start a natural cycle.

Snowpack Summary

There is a lot going on in the snowpack now with all the new snow. 25cm of snow has fallen in this last storm and has become a wind slab in all exposed areas. Another 10cm is forecast to fall on Wednesday, again with strong SW winds. This is simply creating more wind slabs on the surface which are now sitting on a variety of interfaces:

The February 24 storm interface which is down about 20-30cm and consists of suncrust and previous wind slabs. This layer will be sensitive to skier triggering.
The February 3 Rain crust which is down about 40-50cm. This crust has started to break down in many places with facets showing up near the crust- the perfect sliding layer. There is a strong likelihood that any avalanche triggered in the upper snowpack will also step down to this layer.
The November basal facets are alive and well and have come back on our radar as the February 2 rain crust is deteriorating and not locking in the weaknesses below as it once did. Skier weight has now been able to break through the Feb 2 rain crust in some places, which means that the basal facets can now be more easily affected.
On top of all of this, we also have a loose dry avalanche problem.

Weather Summary

The next storm is set to begin on Wednesday bringing 10cm of snow by the end of the ski day. This storm is expected to bring a total of 20-30cm of snow by Friday morning, along with 70-90km/hr winds from the SW.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
Avoid traveling in runout zones. Avalanches have the potential to run to the valley floor.
Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

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.