Avalanche Forecast

Archived

Mar 1st, 2023–Mar 2nd, 2023

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.

Intense wind transport is leading to fresh and sensitive wind slabs. Choose low angle terrain, and avoid overhead hazard.

Confidence

Moderate

Avalanche Summary

A couple of new naturally triggered avalanches were observed in the Goat Range Wednesday afternoon. These were size 2, approximately 100cm deep, but did not propagate widely. The avalanches occurred in steep Alpine terrain on an east aspect, and one of them was possibly triggered by a cornice failure.

Snowpack Summary

Up to 25cm of recent storm snow gave excellent skiing Wednesday, but unfortunately the wind increased to strong from the North by the end of the day and was disturbing the snow. The wind is forecasted to shift to the SW on Thursday. Intense wind transport was occurring at Treeline and above, and it is highly likely that touchy wind slabs are forming at these elevations. Today field teams found easy shears down 25cm, and these shears will only get worse with the increased winds. There are also moderate shears down 30 to 50cm on various versions of old wind slab interfaces. The midpack is strong in deeper snowpack regions near the divide, but the basal facets/depth hoar persist. An avalanche initiated in the upper snowpack could easily step down to the deep persistent weak layers, causing a very large avalanche.

Weather Summary

Thursday will be quite wintery! Temperatures will stay between -13 and -15 all day with SW winds up to 100km/h. Snowfall amounts should reach 10cm by the end of Thursday with a further 2 to 4cm by Friday.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.