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Avalanche Forecast

Archived

Dec 28th, 2013–Dec 29th, 2013

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

Regions

Cariboos.

Confidence

Poor - Due to the number of field observations

Weather Forecast

Tonight and Sunday: Periods of snow around 5-10 cm. The freezing level is near valley bottom and winds are moderate gusting strong from the W-NW. Monday: Flurries or periods of snow 5-10 cm. The freezing level is around 1000-1200 m and winds are light to moderate from the west. Tuesday: Cloudy with a chance of flurries. The freezing level is near valley bottom.

Avalanche Summary

Reports from the past couple days are very limited; however, it's likely that the combination of new snow, wind, and mild temperatures kicked off a natural avalanche cycle in some areas. The additional load may have also been enough to trigger deep persistent weaknesses in isolated areas.

Snowpack Summary

Storm snow totals vary across the region but are generally between 30 and 40 cm. Freezing levels peaked near 1600 m on Friday and have since dropped significantly. A new surface crust is possible at lower elevations. Expect to find touchy wind slabs in exposed lee terrain at and above treeline. A couple buried weak layers (surface hoar or facets) are now down 80-100 cm deep. Recent snowpack test results on these layers vary, but some are showing this layer "pop" with easy to medium loads, indicating a potential for human triggering.Snowpack depths vary, but in general up to 150 cm of snow can be found at treeline, with 100-200 cm in the alpine. In many places we're still dealing with a relatively thin snowpack (thanks to a windy early season) so there's not a whole lot of snow between riders and the sugary snow (facets) near the ground. The basal facet/crust combo has been recently active in parts of the region and continues to give easy to moderate results in snowpack tests.

Problems

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.

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.