Avalanche Forecast

Archived

Mar 13th, 2023–Mar 14th, 2023

Alpine

Natural and human triggered avalanches likely.

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

Banff Yoho Kootenay, Banff, East Side 93N, Kootenay, Lake Louise, LLSA, Sunshine, West Side 93N, Field.

Precipitation will taper by Tuesday morning. Though snow accumulation values are uncertain we expect the avalanche danger to be elevated as this new snow will add load to an already weak snowpack. Stay out of avalanche terrain for a few days as the snowpack adjusts to the new load.

Confidence

Moderate

Avalanche Summary

Limited observations on Monday due to poor visibility. No new natural avalanches were observed today. Local ski hill reported several storm/wind slabs initiated by ski cuts to size 1 in the alpine. Explosive control work produced results on the deep persistent problem to size 2.

Snowpack Summary

10-30cm of recent storm snow overlays a crust on steep solar aspects and surface hoar/facets on polar aspects. The midpack is comprised of various Jan PWL interfaces (sun crusts, facets, and surface hoar) that are now down 40-80 cm. The weaker Nov. 16 basal facet layer is down 50-120 cm producing variable results in snowpack tests.

Weather Summary

A strong South West flow will continue to bring precip Monday night, with higher snowfall values to the Western slopes of the region. The snow will taper by Tuesday morning as a cold front moves in. By Tuesday morning freezing levels will drop to the valley bottom, and winds will gradually decrease to 30 km/h from the West.

For a more detailed forecast click here.

Terrain and Travel Advice

Uncertainty is best managed through conservative terrain choices at this time.
Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.

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.