Avalanche Forecast

Kootenay Boundary

Date issued

Jan 14, 2018 - 3:31 PM

Valid until

Jan 15, 2018 - 2:00 PM

Prepared by

jfloyer

A Special Public Avalanche Warning is in effect for this region.

Continued warm temperatures and sunshine are expected to maintain elevated avalanche danger.

Regular season
Sunday - January 14, 2018
Alpine

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.

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

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.

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

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.

Tuesday - January 16, 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

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.

Avalanche Problem 1: Persistent Slabs

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

Our complex snowpack is currently producing very large and destructive avalanches on up to four separate weak layers buried 50 to 120cm below the surface. Expert level knowledge and experience is required to safely venture into the backcountry.

Travel and Terrain Advice
  • Only the most simple non-avalanche terrain free of overhead hazard is appropriate at this time
  • Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Avalanche Problem 2: Loose Wet

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

Warm temperatures and sunshine are expected to destabilize slopes that face the sun on steep terrain.

Travel and Terrain Advice
  • Small sluffs may step down to deeper layers resulting in large avalanches.

Avalanche Summary

Very significant avalanche activity occurred in the region last Wednesday and Thursday. A smaller avalanche cycle, mostly affecting the recent storm snow was reported on Saturday. While the weather remains warm, there is still an increased likelihood of triggering something large.

Snowpack Summary

Warm alpine temperatures have made the snow surface moist on slopes that face the sun. Below the surface, 40 to 60 cm of recent snow has settling into a cohesive slab on top of the reactive January 5th interface which consists of a crust/surface hoar combination on steep southerly aspects and pure surface hoar on remaining aspects. The late December surface hoar also remains reactive and is now down 50 to 90 cm below the surface.

Adding to the complexity of the mid to upper snowpack is the mid-December surface hoar which is now 60 to 120 cm below the surface. This spooky interface continues to produce sudden snowpack test results and is most pronounced at treeline, but is also present below treeline. The overlying slab is now deep, dense and destructive.

Two laminated crusts created by rain events in late November lay just below the mid-December interface, and may co-exist with facets. In shallow, rocky terrain the mid-December surface hoar and the late November crust seem to be reacting together which is a volatile combination.

Weather Forecast

Monday: A mix of sun and cloud with warm air remaining at higher elevations and cold air remaining in the valleys. Freezing level 3000m. Light southeasterly winds.

Tuesday: Cloud increasing. Light rain or snow in the afternoon, 2-4 mm. Freezing level dropping from around 2500m in the morning to around 1800m in the afternoon. Moderate southerly winds.

Wednesday: Light snow, around 5 cm, increasing in the evening. Freezing level around 1400m. Moderate southerly winds.

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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