Archived

Avalanche Forecast

Apr 10th, 2017–Apr 11th, 2017

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: Banff Yoho Kootenay.

Excellent spring skiing continues with new snow in the forecast for Tuesday. Keep in mind that it is still possible to trigger the deep persistent facets in steep terrain, especially from thin areas or with large triggers such as cornices.

Weather Forecast

Unsettled spring weather could bring as much as 10-15cm of new snow on Tuesday with light SE winds and temperatures remaining cool. Freezing levels are forecast to stay below 1800m. A slight clearing trend and continued cool temperatures is forecast for Wednesday with a few more flurries.

Snowpack Summary

Another 10-15cm Sunday night brings the recent snowfall to between 20-40cm. This new snow is generally bonding well with some isolated pockets of wind slab in the alpine. Below tree line the surface snow is moist on solar aspects. At tree line and above a 120cm+ firm slab with few weaknesses overlies weaker basal facets in much of the region.

Avalanche Summary

A few loose moist avalanches up to size 1.5 were observed out of steep solar alpine terrain on Monday near Lake Louise. Explosive control produced a couple size 1.5-2 slab avalanches in the recent storm snow with minimal propagation. Ski areas reported being able to ski cut small wind slabs from the recent snow up to size 1 that were running far.

Confidence

Intensity of incoming weather systems is uncertain on Tuesday

Avalanche Problems

Deep Persistent Slabs

The snowpack is slowly gaining strength, but the weak basal facets continue to produce sudden collapse results and can produce large avalanches with large triggers. Stick to planar, supported slopes with a deeper snowpack if entering steep terrain.

Be aware of thin areas that may propogate to deeper instabilites.Pay attention to overhead hazards like cornices which could easily trigger deep slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 4

Cornices

April is cornice failure season, and we continue to get reports of cornices failing and triggering deep slabs. Mature cornices can also break much further back than you expect, so give them a wide margin when traveling on ridges.

Do not travel on slopes that are exposed to cornices overhead.Stay well to the windward side of corniced ridges.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 3

Loose Dry

Another 5-10cm of snow is forecast for Tuesday so we expect to see sluffing out of steep alpine and tree line terrain as this new snow arrives. We may also see a few small wind slabs near ridge crests so enter lee loaded terrain with caution.

Be cautious of sluffing in steep terrain, particularly where the debris flows into terrain traps.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2