Avalanche Forecast

Archived

Feb 12th, 2023–Feb 13th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Regions

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

Continued strong West winds are likely to keep wind slabs in the alpine and at treeline reactive. Sheltered tree's may still have soft unaffected snow.

Confidence

Moderate

Avalanche Summary

A few size 1.5 wind slabs out of immediate lee features observed on a flight through the spray valley yesterday. None of these windslabs appeared to stepdown to weaker layers. Otherwise no new or reported slides.

Snowpack Summary

Treeline and alpine windslabs continue to be the main avalanche concern in terms of "triggerability". They are improving with the the relatively warm temperatures, but still expect to find reactive pockets in steep and/or convex terrain. In terms of consequence, the dreaded Nov 5 facets still have a firm grip on the low probability/high consequence title. Some of our neighbours to the west have seen failures on this layer, which suggest loading is a critical factor in when this layer will fail.

Weather Summary

Tonight may bring up to 5cm of much needed snow. The winds continue to wreak havoc. 50-60 km winds out of the west persist for the coming days. A mix of sun and cloud and day time highs of -10 throughout the day.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
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.

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.