Avalanche Forecast

Issued: Jan 9th, 2015 7:42AM

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

ccampbell, Avalanche Canada

Purcells.

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

Summary

Confidence

Good

Weather Forecast

The forecast period is looking mostly cloudy with a chance of light flurries especially on Saturday. Freezing levels remaining in valley bottoms for the forecast period, with no more warm air expected at higher elevations. Winds should remain generally light and variable.

Avalanche Summary

Reports from Thursday include several explosive triggered storm slab and persistent slab avalanches up to Size 3, some stepping down to deeper persistent weak layers near the ground.

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

Storm Slabs

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

Give cornices a wide berth when travelling on or below ridges.>The new snow will require several days to settle and stabilize.>Be careful with wind loaded pockets while approaching and climbing ice routes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

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.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Jan 10th, 2015 2:00PM