Avalanche Forecast

Archived

Nov 21st, 2024–Nov 22nd, 2024

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.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

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

We have had upwards of 35cm of new snow this week with another 10cm forecast. Winds are expected to increase on Friday and bring the hazard to Considerable. Be cautious when approaching tree line and open areas.

Confidence

Moderate

Avalanche Summary

3 new avalanches within the storm interface were observed today in the Highwood Pass region and 1 along the Spray road. As the winds increase on Friday, we will get to the tipping load to trigger avalanches. This photo is in the Dogleg area along the Spray Road that happened sometime on Thursday.

Snowpack Summary

Another 15cm of snow on Wednesday night for an average storm snow of 20-35cm. The height of the snowpack varies from 60-90cm.

The forecasters went into the Pocaterra region at Highwood Pass today. The two layers that we are tracking right now are the storm interface down about 30cm and the October crust down 40-50cm. The recent storm snow is settling and has produced a few new avalanches in the last 48hrs. The October crust is predominant on North and East aspects and not observed on South aspects but is still producing whumphing. As the winds increase on Friday, the rating will become Considerable.

Weather Summary

See image Below. Temperatures on Friday will be between -4 and -9c.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
Be cautious of buried obstacles, especially below treeline.
Keep in mind a buried crust offers an excellent bed surface for 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.