Date issued

Jan 13, 2018 - 5:11 PM

Valid until

Jan 14, 2018 - 4:00 PM

Prepared by

conrad janzen

This is a good time to be conservative in your terrain choices and minimize exposure to avalanche terrain. The chances of human triggered avalanches are quite high and as temperatures increase we will start to see more natural activity as well.

Regular season
Saturday - January 13, 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

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.

Below 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.

Sunday - January 14, 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

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.

Below 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.

Monday - January 15, 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

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.

Below 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.

Avalanche Problem 1: Persistent Slabs

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

There is a widespread weak layer of surface hoar from Dec 15th down 40-60 cm with a stiff enough slab over it to start producing avalanches. Be very careful and travel conservatively even if you observe no avalanches.

Travel and Terrain Advice
  • Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.
  • Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Avalanche Problem 2: Wind Slabs

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

New wind slabs were forming at treeline and in the alpine Saturday with the moderate to strong West winds and warmer temperatures. Watch for the changing feel of the snow under your feet and be wary of areas with denser surface snow over weaker snow.

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

Avalanche Summary

A couple natural avalanches up to size two from the past 48 hrs were observed at treeline in the Little Yoho region. These had failed on the Dec 15 surface hoar interface. Sluffing was observed in the alpine due to strong West winds. Lots of whumphing and cracking in open glades at treeline during a trip to Mt Field on Saturday.

Snowpack Summary

Moderate to strong W winds and warming temperatures are forming wind slabs in the alpine. There is 40-65 cm over the Dec.15 persistent weak layer of surface hoar at treeline. This is becoming reactive to skiers and producing easy to moderate results as shown in this video from Mt Field. Below this is a faceted but generally supportive snow pack.

Weather Forecast

The winds will decrease on Sunday afternoon and the gradual warming continues as the high pressure system arrives. On Monday and Tuesday we expect an inversion to build with alpine temperatures forecast to be just above freezing. Valley bottom temperatures will remain at or below freezing. No significant precipitation is expected.

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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