Avalanche Forecast

Issued: Dec 29th, 2016 4:06PM

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

cgarritty, Avalanche Canada

Cariboos.

Enjoy the new snow but stay tuned in to signs of consolidation and wind effect as you travel. New storm slabs will be touchy on Friday.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: Mainly cloudy with sunny periods and no new snow. Winds light to moderate from the west. Alpine temperatures to -12.Saturday: Mainly cloudy with isolated flurries and a possible 5cm of new snow. Winds light from the north. Alpine temperatures to -12.Sunday: A mix of sun and cloud with no new snow. Winds moderate gusting to strong from the north. Alpine temperatures around -17.

Avalanche Summary

No new natural avalanches have been observed in the region but slope cutting on Wednesday in the Valemount area produced a size 1.5 avalanche with a 60cm crown depth. It is likely that limited observations and conservative terrain choices are obscuring some of the avalanche potential in the region. Expect our continued moderate to strong ridgetop winds along with new snow on Thursday to promote ongoing slab development - particularly in wind-exposed areas. In more sheltered areas, watch for signs of storm snow consolidating into a slab as well as loose dry avalanches triggering easily in steep terrain.

Snowpack Summary

About 35cm new snow lies on the surface after this week's series of storms. In higher elevation terrain, moderate to strong winds have promoted slab formation on lee and cross-loaded features. In sheltered areas and lower elevations, the low density snow has only just begun to show signs of consolidation into soft slab. 65-100cm below the surface you'll find the mid-December interface which consists of a variety of old snow surfaces including wind affected snow, faceted (sugary) crystals, and/or surface hoar crystals. Recent tests suggest the the new snow is well bonded to the interface in some areas. However, a few public and professional reports suggest this layer may be reactive in some areas and worth investigating before pushing into steeper terrain. The thick mid-November crust layer typically sits 1-2 m down in the snowpack. This layer is considered dormant at this time but remains an isolated concern that we will likely be tracking through much of the season.

Problems

Storm Slabs

Avalanche danger will increase as low-density storm snow settles into a slab. Watch for signs like cracks in the snow to tell you this is taking place and expect slab formation to be a step ahead of you in wind exposed areas.

Be alert to conditions that change with elevation.Avoids areas where the surface snow feels stiff or slabby.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Loose Dry

Slab avalanches aren't the only danger out there. Expect loose dry avalanches to trigger easily and entrain lots of snow in gullies and other steep features that are sheltered from the wind.

Be cautious of sluffing in steep terrain.Use safe ski cutting techniques before entering steep features.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

A mid-December weak layer has generated some isolated reports of large avalanches in the Columbia mountains to the south. This layer exists in the Cariboos as well, and may be easier to trigger in thin snowpack areas on the eastern edge of the range.

Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 30th, 2016 2:00PM