Avalanche Forecast

Sea To Sky

Date issued

Dec 6, 2017 - 3:35 PM

Valid until

Dec 7, 2017 - 2:00 PM

Prepared by

shorton

Alpine temperatures are sky rocketing! Dial back your terrain choices when the snow gets moist or mushy and avoid cliffs, gullies, and steep slopes with trees.

Regular season
Wednesday - December 6, 2017
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 - December 7, 2017
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.

Friday - December 8, 2017
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.

Avalanche Problem 1: Loose Wet

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

Conditions will be more like spring than winter this week. Surface snow layers can become weak when hit by the sun. Minimize your exposure to terrain traps - even small sluffs can push you into dangerous terrain.

Travel and Terrain Advice
  • Use caution above cliffs and terrain traps, where small avalanches may have severe consequences.
  • Use extra caution on sunny slopes or if the snow is moist or wet.

Avalanche Problem 2: Wind Slabs

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

Isolated winds slabs have formed on a variety of aspects at higher elevations, and in some cases sit above a buried crust. Be careful on steep convex terrain or where the wind has blown the snow into more cohesive slabs.

Travel and Terrain Advice
  • Use ridges or ribs to avoid pockets of wind loaded snow.
  • Avoid steep lee and cross-loaded features
  • Be alert to changing snow conditions, especially where the snow firms up or sounds hollow.

Avalanche Summary

On Tuesday, a few small loose avalanches were reported on steep south-facing slopes, showing the initial effects of the warm weather. More wet loose activity can be expected thanks to the sustained warming this week.

Snowpack Summary

Dramatic warming will cause widespread melting of the surface snow, especially on south-facing slopes. Crusts may form overnight, but will melt quickly in the mornings. The 40-60 cm of storm snow that fell last week is rapidly settling and bonding well to the late November rain crusts. Up high, shifting winds (first from the south, and more recently from the north) have blown snow around in exposed areas creating drifts and scoured areas.

Weather Forecast

THURSDAY: Sunny, light wind, freezing level around 3200 m.

FRIDAY: Sunny, light wind, freezing level around 3000 m.

SATURDAY: Increasing cloud, moderate to strong southwest wind, freezing level around 2500 m.

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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