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Avalanche Forecast

Archived

Jan 14th, 2020–Jan 15th, 2020

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
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 possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

Banff Yoho Kootenay.

Extreme cold has helped conditions. However, a warming trend and incoming snow starting Thursday will elevate the hazard rating.

Weather Forecast

The polar vortex persists, but there is light at the end of the tunnel. A slight warming trend is starting tomorrow and valley temperatures are expected to crest at about -5 on Thursday. The incoming warming trend will bring approx 15cm by Friday morning. Throughout this period wind will be strong from the SW and then drop to light.

Snowpack Summary

30-50 cm of snow since Dec 31 sits over a variety of surfaces including facets, surface hoar and sun crust. Windslabs may still exist in leeward alpine areas. In most areas there is a settled mid-pack over top of weaker basal layers.

Avalanche Summary

Sunshine Patrol heard to large audible avalanches in the Delerium Dive area which were cornice triggered this afternoon. No other avalanches observed or reported.

Confidence

Due to the number and quality of field observations on Tuesday

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.

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.