Avalanche Forecast

Archived

Feb 13th, 2012–Feb 14th, 2012

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Kootenay Boundary.

Confidence

Good - -1

Weather Forecast

Flurry activity is expected to taper off by Tuesday morning. A building ridge of high pressure is expected to spread dryconditions Wednesday through Thursday morning before a frontalsystem arrives late Thursday bringing light precipitation. Freezing levels should remain near 1000m and winds should be light and variable throughout the forecast period.

Avalanche Summary

Surface snow has been sluffing readily with rider traffic on steep slopes and strong solar radiation has resulted in afternoon snowballing and isolated small wet loose avalanches. Deep persistent slab avalanches remain possible with heavy triggers in shallow rocky snowpack areas on unsupported slopes.

Snowpack Summary

5-15cm of fresh snow is sitting on a thin weak crust capping 2-5cm of moist snow that rests on top of robust surface hoar created during the dry spell at the beginning of the month. This interface will be one to watch as it receives more snow load and/or the slab settles. Below that 30cm of near-surface facets can be found on shady slopes while a sun crust can be found on southerly aspects. Concerns remain for the mid-December persistent weakness down around 80-100cm and for basal facets in shallow snowpack areas.

Problems

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.