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Avalanche Forecast

Archived

Dec 4th, 2017–Dec 5th, 2017

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

Regions

Northwest Inland.

Lingering wind slab and persistent slab problems will keep avalanche danger in a holding pattern for one more day. Warm temperatures are set to undermine stability in the midweek.

Confidence

Moderate -

Weather Forecast

Tuesday: Mainly cloudy with isolated flurries and a trace of new snow. Light to moderate west winds. Weak alpine temperature inversion bringing alpine temperatures to around -2.Wednesday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light southwest winds. Freezing level rising to over 3000 metres with alpine temperatures around +5. Cooler temperatures at valley bottom due to temperature inversion.Thursday: Mainly sunny with some valley cloud due to lingering temperature inversion. Light to moderate southwest winds. Freezing level to over 3000 metres with alpine temperatures around +5. Cooler temperatures at valley bottom.

Avalanche Summary

No recent avalanche activity has been reported. Stiff wind slabs may exist at treeline and in the alpine on leeward slopes and cross-loaded features. If triggered, these could step down to trigger deeper weak layers and initiate large avalanches. The last significant avalanche observation was submitted on November 28th from Skilokis Creek. Here, a size 2.5 persistent slab was triggered from 150 m away. This problem will likely linger. Check out the Mountain Information Network for more details. Give info, get info.

Snowpack Summary

Average snowpack depths now total 80-140 cm at treeline elevations and up to 160 cm in the alpine. Alpine snow surfaces are likely wind affected. Below the surface, approximately 30-50 cm of recent snow now overlies two crusts that were buried near the end of November. These crusts are widespread and extend well into the alpine. Recent snowpack tests have shown sudden results at these crust interfaces. Below these crusts, we have a well settled midpack overlying the late October crust near the base of the snowpack. This late October "crust/facet combo" is widespread and has been reactive to rider and remote triggers.

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.

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.