Avalanche Forecast

Archived

Mar 13th, 2025–Mar 16th, 2025

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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.

Light snow will continue to fall over the next few days. The natural avalanche cycle has tapered but forecasters still have little confidence in the overall snowpack structure and continue to avoid any slopes that have potential for consequence.

Confidence

Moderate

Avalanche Summary

Forecasters were able to easily ski cut numerous sz 1 avalanches in open treeline terrain on thursday. One sz 2 natural winslab avalanche was also observed on an east aspect around 2300m.

Observations were limited due to ongoing snowfall.

Snowpack Summary

5cm of snow throughout the day on Thursday with moderate to strong winds at ridgetop have further developed the windslabs that have been building over the past few days. Out recent snow has now settled to around 40cm on average at treeline. This snow is overlying either a sun crust on solar aspects, (march 3rd interface) or a previous windslab on the more northern aspects. Windslabs in the upper snowpack 5-30cm thick are being observed along ridgelines and along cross loaded features. Ski cutting on Thursday was was generating sz 1's commonly in open terrain.

Our second problem consists of a persistent slab that is overlying the Jan 30th layer down 60 to 90cm. This slab is widespread through the region and covers the very weak mid-pack and basal layers. This combination is producing widespread large settlements with skier traffic, which indicate a collapse of this dense layer onto the weaker base - a perfect recipe for avalanches.

Human triggering of the wind slab and/or the persistent slab is very likely, and several large naturally triggered avalanches are still occurring.

Traveling off of established skin tracks at lower elevations is very challenging due to the weak nature of the snowpack.

Weather Summary

5-8cm of snow is forecast starting Thursday night and into Friday morning. Temperatures are going to cool to -11C overnight and only warming up to -8c during the day. Winds will be moderate out of the SW at ridgetop.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Continue to make conservative terrain choices while the storm snow settles and stabilizes.
Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.

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.