Date issued

Mar 20, 2018 - 4:00 PM

Valid until

Mar 21, 2018 - 4:00 PM

Prepared by

grant statham

The first day of spring was a blustery one near Lake Louise! The winds have destroyed the good quality surface snow and changed the conditions dramatically in the past 24-hours. This is not the case everywhere and some areas have received new snow.

Regular season
Wednesday - March 21, 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.

Thursday - March 22, 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

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.

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.

Friday - March 23, 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?

24 hours of sustained winds from the SW has created windslabs up to 30 cm thick in leeward areas, mostly in the alpine. The are unlikely to release naturally but can be triggered by skiers and climbers.

Travel and Terrain Advice
  • Use caution in lee areas. Recent wind loading have created wind slabs.

Avalanche Problem 2: Persistent Slabs

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

On steep solar terrain the recent storm snow (20-30cm) is sitting on a suncrust that was buried on March 15. These types of problems can be tricky due to their isolated nature, but be cautious on any steep south or west facing terrain in the alpine.

Travel and Terrain Advice
  • Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.

Avalanche Summary

A size 1 windslab was triggered by skiers on a classic leeward slope under a cornice today - 25 cm deep by 50 m wide. Several large avalanches have been triggered by skiers over the past few days - these seem to be in isolated locations but the common theme has been West aspect on suncrust.

Snowpack Summary

Convective flurries have deposited new snow in some areas of the park and not in others, so the surface conditions are quite variable. 24-hr of wind near Lake Louise has created widespread wind effect in all open terrain at treeline and in the alpine. On south and west aspects these slabs may bond poorly to a suncrust down approximately 30-50 cm.

Weather Forecast

The unsettled weather continues again on Wednesday with clouds and a few flurries ending by noon - the afternoon should see some clearing and freezing levels reaching 2100 m. Friday might be the snowy day this week and temperatures are forecast to fall below -15 for the start of the weekend.

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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