Avalanche Forecast

Issued: Mar 9th, 2014 6:14PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

The natural cycle is slowing down but skier triggering of avalanches remains likely. Choose moderate terrain with minimal exposure to large paths, and watch for the effects of daytime heating as we move into more spring like weather. CJ

Summary

Weather Forecast

Alpine temperatures between -10'C and -3'C are forecast for the next several days, with a mix of sun and cloud, occasional light flurries, and light to moderate winds out of the West.

Snowpack Summary

85-100cm of storm snow has fallen in the Sunshine, Kootenay and Yoho areas, with 40-60cm around Lake Louise and Bow Summit since Mar 2nd. This storm snow has overloaded the Feb 10th layer of facets, surface hoar and sun crust, causing avalanches with wide propagations. Moderate SW winds have also created wind slabs in open areas above tree line.

Avalanche Summary

A widespread natural avalanche cycle to size 3 occurred on all elevations and aspects today. Much of this is occurring on the Feb 10th layer however we also observed storm slab releases and some deep releases to ground. The cooler temperatures over the next several days will slow down the natural cycle, but skier triggering will remain a concern.

Confidence

Problems

Storm Slabs

The recent storm snow and wind slabs will slowly begin to bond to the lower layers in the snowpack but this will take some time. Choose conservative terrain with no overhead hazard until this has a chance to bond.

Be cautious as you transition into wind affected terrain.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The Feb 10th layer continues to be reactive in many areas especially at tree line. Avoid any steep terrain until this has a chance to bond.

Dig down to find and test weak layers before committing to a line.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

With the cooling temperatures this will become less reactive to skier traffic. Large triggers such as cornice drops or large slab releases could still cause failures on the basal facets.

Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Mar 10th, 2014 4:00PM