Avalanche Forecast

Archived

Mar 2nd, 2023–Mar 3rd, 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.

Westerly winds and up to 10cm of snow on Thursday is adding more load to the current windslab problem at treeline and above. Be aware of the potential for large avalanches that involve the entire winters snowpack. Thin snowpack areas should be avoided.

Confidence

Moderate

Avalanche Summary

No new avalanches were observed on Thursday but visibility was limited due to snowfall during the day and associated clouds.

Snowpack Summary

Up to 35cm of recent storm over the past few days is being moved around by the strong winds creating and adding to the previous windslabs that existed in the region. Field teams have been finding easy shears down 25-35cm, and these shears that are reactive to skier traffic. Moderate shears also persist 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. Always have full depth avalanche on your mind.

Weather Summary

Strong SW winds continued on Thursday but are forecast to become more moderate by friday morning. Another 5cm of snow is likely to fall overnight with temperatures around -15 in the morning warming up to -11 by mid day. Its still full on winter out there these days!

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
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.