Avalanche Forecast

Issued: Dec 3rd, 2012 8:04AM

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

danyelle magnan, Parks Canada

Glacier.

We received 20cm of snow in the past 24hrs. The storm slab is thick enough to produce large avalanches. Natural avalanches from steep paths have been running to valley bottom. Spread out and put in the higher track up Connaught to minimize exposure.

Summary

Weather Forecast

Another 5-10cm are expected today with strong SW winds. A strong pacific front will move into the region on Tuesday bringing another 10-20cm, high to extreme SW winds at ridgetop and freezing levels rising to 1500m. On Wednesday, with the passage of the front unsettled conditions will continue with light to moderate precipitation and strong W winds

Snowpack Summary

A 60cm storm slab is becoming increasingly cohesive. This overlies the Nov28 layer which will be most reactive where it overlies a suncrust on S slopes or where surface hoar was buried; sheltered areas at treeline. Moderate-strong S'ly winds have formed soft slabs and loaded lee slopes. The Nov 6 crust may become reactive with increasing load.

Avalanche Summary

Natural avalanche activity has been occurring from steep complex terrain during periods of intense wind and snowfall. Most are size 2-2.5, and several paths have run repeatedly, some running to the end of their runouts. There have been reports of natural avalanches from the Cheops north paths.

Confidence

Problems

Wind Slabs

Moderate to strong S-SW winds have loaded lee slopes, triggering natural avalanches in steep terrain. Expect touchy loaded pockets, and soft windslabs on lee slopes.

Avoid lee and cross-loaded terrain near ridge crests.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Storm Slabs

We've received 60cm of snow in the past 4 days. This soft slab will be most reactive where it buried surface hoar or sun-crust. We expect more snow and strong winds today, which may overload these layers resulting in natural avalanches.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.Choose well supported terrain without convexities.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

The Nov 6 crust complex has yet to wake up. While the likelihood of triggering is low, it will produce large avalanches. As the load on this layer increases, it may become reactive. Smaller avalanches may step down to this deeper layer.

Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 4th, 2012 8:00AM