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Avalanche Forecast

Archived

Jan 29th, 2022–Jan 30th, 2022

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

Regions

Purcells.

Storm slab avalanches will become more likely throughout the day as the new snow accumulates and buried the surface hoar crystals and the melt-freeze crust.

Confidence

Moderate - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather. Uncertainty is due to the timing of the incoming weather system.

Weather Forecast

The weather pattern is changing as the upper ridge of high pressure over B.C. has flatten allowing the Pacific system to move over the province.

SATURDAY NIGHT: Increasing cloudiness with isolated flurries, accumulation 1 to 3 cm, 30-40 km/h southwesterly winds, low alpine temperature -10 C with freezing level at valley bottom.

SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm during the day and 10 to 20 cm overnight, 30-50 km/h southwesterly winds, high alpine temperature -5 C with freezing level at valley bottom.

MONDAY: A mix of sun and cloud with isolated flurries, accumulation 1 to 3 cm, 30-40 km/h westerly winds, high alpine temperature -7 C with freezing level at valley bottom.

TUESDAY: A mix of sun and cloud with scattered flurries, accumation 3 to 5 cm, high alpine temperature -10 C with freezing level at valley bottom.

Avalanche Summary

No recent avalanches have been reported.

Avalanche activity on the early-December weak layer described in the snowpack summary has been sporadic over the past few weeks. We tend to see reports of avalanches on this layer every few days, being triggered naturally from the weather or occasionally by riders. Most of the avalanches occurred at elevations around 2000 m. Possible natural triggers include daytime warming, warming from the sun, cornice falls, or smaller avalanches stepping down. Human triggering is most likely in steep, rocky slopes with a shallow or thin-to-thick snowpack.

Snowpack Summary

Alpine terrain has widespread wind effect. Surface hoar crystals are found in sheltered areas and a melt-freeze crust on solar aspects. These will be important layers to track as they get buried by new snow. 

Some older thin surface hoar layers are 20-40 cm deep, but have not been producing concerning results in recent snowpack tests. 

The most notable layer of concern in the snowpack is a facet/crust layer that formed in early December and ranges in depth between 70 cm along the shallower eastern Purcells and up to 150 cm in the western Purcells.

Terrain and Travel

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • 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.