Avalanche Forecast

Issued: Mar 21st, 2014 4:20PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Great skiing can be found and we are slowly gaining confidence in the snowpack. But given the Feb 10th layer is so widespread in the region and showing sudden results on South aspects, we recommend conservative, low consequence route choices.

Summary

Weather Forecast

Mix of sun and cloud for the weekend, highs of -10, and winds will be light westerly with occasional gusts. These weather inputs will not significantly affect the hazard rating and we should see a gradual improvement in the avalanche hazard.

Snowpack Summary

5-10 new overnight, a thin sun crust on steep solar aspects. In the Lake Louise region, field tests on south aspects, the Mar 2nd suncrust/facet layer, down 40 cm, and the Feb 10 crust/facet, down 80 cm, produced moderate to hard sudden failures with the potential to propagate, Fewer results on North aspects.

Avalanche Summary

There was one size 2.5 explosive controlled avalanche in Lake Louise area, slid to ground, N aspect, previously controlled terrain. One size 1 sluff observed out of steep rocky terrain NW aspect. Watch out for natural activity related to solar heating over the weekend. Earlier this week, there was a cornice triggered size 3 in the Sunshine region.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

Slowly this layer is becoming less reactive, but it remains a concern. Field tests, particularly on southern aspects, confirms this. It's now down 80-120 cm and more likely triggered from thinner areas or by larger loads.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Avoid areas with overhead hazard.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Persistent Slabs

A 5 cm thick suncrust with facets on top exists on solar aspects with moderate sudden shears and is down approximately 40 cm.. An avalanche triggered on this layer could step down to the Feb 10th layer resulting in a larger avalanche.

Use careful route-finding and stick to moderate slope angles with low consequences

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Wind Slabs

Confined to immediate lee of alpine features.

Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 22nd, 2014 4:00PM