Avalanche Forecast

Issued: Dec 12th, 2012 9:10AM

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

slemieux, Avalanche Canada

Purcells.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

A weak system will cross the region in the evening Thursday bringing flurries and light North West winds becoming moderate from the South West later.Â Temperatures will stay cool for the entire period. Similar conditions are expected for Friday and Saturday except for the winds turning back and forth from the North West to South West and staying light for the rest of the period.

Avalanche Summary

No new natural or skier triggered avalanche was reported recently except for explosive results up to size 2 that ran on West and North West aspects down 40-80 cm on facets. Check out this avalanche report from the Kicking Horse backcountry.from December 10th.

Snowpack Summary

The 5-10 cm of new snow that fell in the past couple days is sitting on the older storm snow and is continuing to settle. Some isolated windslabs exist in the alpine and at treeline on Easterly aspects and on cross loaded features. This loads 2 surface hoar and/or facet layers that were buried at mid November and then, at the end of November. Except for explosive results, recent snowpack tests gave no significant results on these weaknesses located consecutively around 50 cm and 100 cm below the surface of the snowpack. Near the base of the snowpack is the early November crust/facet deep persistent weakness. It would be possible to trigger if you hit the right spot, like a thinner snowpack area on a slope with smooth ground cover.Â

Problems

Persistent Slabs

There are two layers of buried surface hoar in the region down 50 cm and down 30 cm. Professionals are still concerned about these layers in unsupported terrain.

Choose well supported terrain without convexities.>If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Deep Persistent Slabs

Typical trigger points include thin rocky areas on steep unsupported slopes. Step-down avalanches are also a concern.

Typical trigger points include thin rocky areas on steep unsupported slopes. Step-down avalanches are also a concern.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Wind Slabs

Watch for pockets of windslabs under ridges especially in the alpine. They could have the potential to propagate widely on large planar slopes.

Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Use ridges or ribs to avoid pockets of wind loaded snow.>

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Dec 13th, 2012 2:00PM