Avalanche Forecast

Issued: Jan 9th, 2018 5:09PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

cgarritty, Avalanche Canada

Cariboos.

Avalanche activity has been on a steady increase. The touchiest conditions are likely to be found in the south of the region where more recent snow accumulated.

Summary

Confidence

Moderate -

Weather Forecast

Wednesday: Mainly cloudy with isolated flurries and a trace of new snow. Light west winds. Alpine high temperatures to -14Thursday: A mix of sun and cloud with isolated flurries and a possible trace of new snow. Light northeast winds. Alpine high temperatures of -11Friday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures of - 8.

Avalanche Summary

Reports from Monday showed limited activity in the Cariboos, with only one ski cut of a small storm slab. With that said, considerably more avalanche activity was observed in the adjacent North Columbias. Here, numerous persistent slabs and storm slabs ran naturally and with remote (from a distance) triggers. Sizes ranged from small to large (Size 1-2) with slab depths of 10-60 cm. Activity was observed on all aspects and elevation ranges. Conditions in the Cariboo region are not drastically different from the North Columbias at the moment, so it is advised to consider activity in this neighbouring region as indicative of the potential that exists in the Cariboos.Please share your observations through the Mountain Information Network.

Snowpack Summary

30-60 cm of new snow now overlies surface hoar on sheltered slopes as well as sun crust on steep solar aspects. The new snow will need time to bond to these surfaces. Moderate southwesterly winds accompanied this snowfall in the alpine, which likely created small wind slabs in lee features.As the new snow consolidates, it may form a dangerous slab above several persistent weak layers that exist deeper in the snowpack. The deepest of these, the December 15 surface hoar, is now buried 50 to 80 cm deep. This layer is shallower in the north of the region and deeper in the south of the region and is found most often at treeline and below treeline. As the snow above the weak layers becomes more cohesive and forms a slab, the setup has the potential to create easily-triggerable destructive slab avalanches. Recent avalanche activity as well as snowpack test results show increasing reactivity at this layer. Deeper in the snowpack at depths of about 70 to 100 cm, a rain crust from November is producing variable snowpack test results, from sudden fracture characters to no result. This layer is considered dormant but could be triggered where the snowpack is thin.

Problems

Storm Slabs

Thick storm slabs have been building at all elevations, especially in the south of the region. Weak layers exist below the new snow as well as deeper in the snowpack and a small storm slab release carries the risk of triggering a deeper weakness

Use extra caution on north aspects. Recent southerly winds may have created wind slabs.Avoid exposure to terrain traps where the consequence of a small avalanche could be serious.If triggered, the storm slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A weak layer buried 40-70 cm deep is becoming increasingly reactive in many areas of the BC interior. This layer has produced numerous large avalanches and is becoming a greater concern in the Cariboos as well - especially in the south of the region.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.Use conservative route selection. Choose moderate-angled and well-supported terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 10th, 2018 2:00PM