Date issued

Apr 16, 2018 - 4:00 PM

Valid until

Apr 17, 2018 - 4:00 PM

Prepared by

jonas hoke

Current avalanche problems have been reactive to light loads recently - the hazard may increase quickly if forecast snowfall amounts are exceeded.

Regular season
Tuesday - April 17, 2018
Alpine

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Wednesday - April 18, 2018
Alpine

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation,cautious route-finding and conservative decision-making essential.

Natural avalanches possible;human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Thursday - April 19, 2018
Alpine

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Treeline

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

Below Treeline

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

Avalanche Problem 1: Wind Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

New snow will bury windslabs in the Alpine and TL, these are overloaded and under tension, and remain sensitive to light loads.

Travel and Terrain Advice
  • If triggered the wind slabs may step down to deeper facet layers resulting in larger avalanches.
  • Use caution in lee areas. Recent wind loading has created wind slabs.

Avalanche Problem 2: Cornices

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

Large cornices in all areas of the bulletin region. When failing these are triggering persistent instabilities and the subsequent avalanches are proving large and destructive.

Travel and Terrain Advice
  • Minimize overhead exposure during periods of heavy loading from new snow, wind.
  • Avoid travel on slopes that are exposed to cornices overhead.

Avalanche Problem 3: Persistent Slabs

What Elevation?
Which Slopes?
Chances of Avalanches?
Expected Size?

A slab up to 1m thick overlies: weak faceted crystals, and sun crusts (on steep S and W aspects). This problem has been reactive recently in North facing terrain.

Travel and Terrain Advice
  • Minimize exposure to overhead avalanche terrain, large avalanches may reach run out zones.
  • Be aware of the potential for wide propagations which could result in large avalanches.

Avalanche Summary

No new avalanches reported today. Check Avalanche Canada's MIN Reports for several recent reports of large avalanches, both natural and skier triggered.

Snowpack Summary

Up to 20cm of snowfall since Thursday and moderate SW winds have built windslabs in open areas at treeline and in the alpine, and continue to add to the cornice problem. Persistent instabilities (down 40-100cm) remain sensitive to triggering, especially on N slopes at treeline and in the alpine. The mid and lower snowpack remain weak and facetted.

Weather Forecast

Flurries continue for the next 24 hours.  Accumulations and loading may vary significantly.  Forecasted snow amounts are up to 7 cm in the Icefields area, with much less in the North.  Freezing levels will fall to valley bottom overnight and rise to 1800m mid-day. Ridge winds will be mainly light and variable, with gusts into the moderate range.

Danger Ratings Explained

1 - Low

Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.

Natural and human-triggered avalanches unlikely.

Small avalanches in isolated areas or extreme terrain.

2 - Moderate

Heightened avalanche conditions on specific terrain features. Evaluate snow and terrain carefully; identify features of concern.

Natural avalanches unlikely; human-triggered avalanches possible.

Small avalanches in specific areas; or large avalanches in isolated areas.

3 - Considerable

Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.

Natural avalanches possible; human-triggered avalanches likely.

Small avalanches in many areas; or large avalanches in specific areas; or very large avalanches in isolated areas.

4 - High

Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.

Natural avalanches likely; human-triggered avalanches very likely.

Large avalanches in many areas; or very large avalanches in specific areas.

5 - Extreme

Avoid all avalanche terrain.

Natural and human-triggered avalanches certain.

Large to very large avalanches in many areas.

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