Avalanche Forecast

Issued: Dec 13th, 2012 9:36AM

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

slemieux, Avalanche Canada

Purcells.

Summary

Confidence

Fair

Weather Forecast

Flurries are expected till tomorrow am with SW-NW moderate winds. Sunny periods and broken clouds are still expected for Friday, seasonal temperatures throughout the period (-8 C) and light winds from the North West.Â The upper trough arriving on Saturday should bring light precipitations on the regions. Winds should pick up to reach moderate to strong speeds from the South West. Another system is following for Sunday, its timing and intensity remains to see.

Avalanche Summary

No new natural avalanches were reported. In the North part of the region,Â multiple small slab avalanches released from explosives in the new snow on Northerly aspects. In the South part of the region, 1 small slab avalanche was released by a skier which ran on a North aspect on the facet crust combo buried in early November. This layer also produced multiple small slab avalanches by explosives on the same aspect above 1950 meters.

Snowpack Summary

Watch for new and old isolated windslabs in the alpine and at treeline on Easterly aspects and on cross loaded features. The main concerns are still the 2 persistent weak layers (early November crust down 60-100cm and Late November surface hoar down 40cm).Â Be aware that triggering an avalanche in a touchier windslabs area could step down to the deeper more stubborn problems. The crust-facet combo seems to be more reactive in the South part of the region. The surface hoar layer seems to be reactive mostly in the North part of the region still producing the odd sudden collapses result on North and North West facing slopes.Â

Problems

Persistent Slabs

The late November surface hoar is located around 40 cm down and is still a concern to the professionals especially 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 14th, 2012 2:00PM