Avalanche Forecast

South Coast

Date issued

Jan 23, 2018 - 5:38 PM

Valid until

Jan 24, 2018 - 2:00 PM

Prepared by

jsmith

New snow and wind are creating deeper and increasingly destructive storm slabs ripe for human triggering. Sticking to simple terrain would be a great way to manage the elevated hazard on Wednesday.

Regular season
Tuesday - January 23, 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

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 - January 24, 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

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.

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.

Thursday - January 25, 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: Storm Slabs

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

An impressive storm has just occurred, and deep and dense storm slabs lurk in lee and cross-loaded terrain. New snow and wind on Tuesday will add to this ongoing storm slab problem.

Travel and Terrain Advice
  • Be alert to conditions that change with elevation and time of day.
  • The new snow will need time to settle and stabilize.
  • Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.

Avalanche Summary

On Tuesday, a size 1.5 skier triggered storm slab avalanche was reported near Mt. Seymour. With more snow and wind on the way, natural and human-triggered storm slab activity should continue throughout the week.

Snowpack Summary

In recent days the region was pummeled by heavy precipitation with the rain line hovering around 800m. As of Tuesday morning, the 72 hour precipitation totals were up to 130mm on the North Shore mountains with closer to 60mm falling north of the Fraser Valley. Strong to extreme winds have redistributed the new snow into deep, dense and potentially destructive storm slabs while rain has saturated the snowpack at lower elevations. The reactivity of the new storm slabs is likely to vary greatly depending on elevation/ temperature and orientation to wind. In general, I would expect the touchiest conditions to exist in exposed, higher elevation terrain.

Weather Forecast

Tuesday Night: 15-25cm of new snow / Moderate to strong southwesterly ridgetop winds / Freezing level rising to around 1400m.

Wednesday: 5-10 cm of new snow / Moderate southwesterly ridgetop winds / Freezing level around 1000m.

Wednesday night: 20-30 cm of new snow / Strong southerly ridgetop winds / Freezing level around 800m.

Thursday: 20-30 cm of new snow / Strong southerly ridgetop winds / Freezing level around 800m.

Friday: 15-20cm of new snow / Light to moderate southwesterly ridgetop winds / Freezing level around 500m.

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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