Avalanche Forecast

South Coast

Date issued

Feb 20, 2018 - 4:44 PM

Valid until

Feb 21, 2018 - 2:00 PM

Prepared by

swerner

The snow is heavily wind-affected. Triggering a wind slab is more likely on southerly slopes where a poor bond to the buried crust exists. Stick to sheltered trees to find the best and safest riding.

Regular season
Tuesday - February 20, 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

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.

Wednesday - February 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 - February 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

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?

Strong northerly winds have formed fresh slabs at higher elevations. Wind slabs may be more reactive to human triggers on solar aspects where they sit on a buried crust. Loose dry sluffing is likely from steeper terrain features.

Travel and Terrain Advice
  • Use caution above cliffs and terrain traps where small avalanches may have severe consequences.
  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.
  • Use ridges or ribs to avoid pockets of wind loaded snow.

Avalanche Problem 2: Cornices

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

Large cornices have formed along ridgelines. Cornices are inherently unstable, unpredictable, and demand respect.

Travel and Terrain Advice
  • Firm cornices may pull back into flat terrain at ridgetop if they fail.
  • Give cornices a wide berth when traveling on or below ridges.

Avalanche Summary

Dry loose avalanches up to size 1 were reactive to skier traffic on Monday.

Snowpack Summary

In exposed terrain, strong north winds have scoured north facing slopes and loaded south facing slopes. In sheltered terrain, cold weather is preserving 30-50 cm of low density snow. A hard rain crust that extends into alpine terrain is buried about 40 cm beneath the recent storm snow. Reports suggest the snow has a poor bond to the crust with test results showing sudden planar characteristics. This means there's a potential for slab avalanches on any steep or convex terrain feature. Monitor the bond of the snow to this crust closely. There are no significant layers of concern below the crust.

Weather Forecast

A fairly benign weather pattern through the forecast period.

Wednesday: Mostly cloudy with some sunny periods and a chance of flurries. An alpine high temperature of -8 with generally light westerly winds and some strong gusts.

Thursday: Mostly sunny with an alpine high temperature of -5. Ridgetop winds light to moderate from the northeast.

Friday: Cloudy with new snow 5-15 cm. Alpine temperatures near -3 and ridgetop winds moderate with strong gusts from the southwest.

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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