Avalanche Forecast

Issued: Jan 10th, 2015 7:48AM

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

jlammers, Avalanche Canada

Purcells.

Diligence may be required to maintain conservative decisions when seeking decent riding conditions over the weekend.

Summary

Confidence

Fair

Weather Forecast

Only trace amounts of snow are expected throughout the forecast period. Overcast conditions are forecast for Sunday, although skies should become increasingly clear on Monday and Tuesday as a dry ridge of high pressure becomes the dominant air mass. Ridgetop winds should remain generally light, while freezing levels will remain at valley bottom.

Avalanche Summary

Reports from Friday include several explosive triggered storm slab and persistent slab avalanches up to Size 2.

Snowpack Summary

There is a great deal of variability across the region. The West and South have received up to 60 cm of storm snow earlier in the week, quickly followed by high freezing levels and warm air up into the alpine which has resulted in a breakable surface crust. The North and East of the region have had 20-30 cm of cold dry new snow which has since been redistributed into touchy soft wind slabs, while large surface hoar is growing in sheltered areas. Deeper in the snowpack there is a persistent weak layer of surface hoar and crust that is now down about 30-80 cm. Recent snowpack tests on the West side of the range produced easy resistant results down 25 cm in the recent storm snow, and moderate to hard but sudden results down 80-90 cm on buried surface hoar sitting on a crust.

Problems

Persistent Slabs

A persistent weakness buried mid-December is primed for human triggers and wide propagations producing very large avalanches. Remote triggering from flat terrain and step-down from shallower weaknesses makes this problem especially tricky to manage.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Storm Slabs

Recent storm snow has settled into thick slabs that have been sensitive to human triggers, especially where wind-loaded. Treat slopes that have yet to slide with suspicion.

The new snow will require several days to settle and stabilize.>Give cornices a wide berth when travelling on or below ridges.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 11th, 2015 2:00PM