Avalanche Forecast

South Coast

Date issued

Apr 6, 2018 - 3:35 PM

Valid until

Apr 7, 2018 - 2:00 PM

Prepared by

mconlan

More precipitation is forecasted for Saturday, with snow at high elevations and rain below. Be cautious of periods of rapid precipitation loading, as avalanche activity may increase.

Regular season
Friday - April 6, 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

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.

Saturday - April 7, 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.

Sunday - April 8, 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

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: Storm Slabs

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

Snowfall at higher elevations has formed new slabs. More snow is forecasted for Saturday, which will build thicker slabs. Observe for the bond of new snow with the old surface before committing into avalanche terrain.

Travel and Terrain Advice
  • Minimize exposure during periods of heavy loading from new snow, wind or rain.
  • Use ridges or ribs to avoid pockets of wind-loaded snow.
  • Pay attention to overhead hazards like cornices, which could trigger slabs on slopes below.

Avalanche Problem 2: Loose Wet

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

Precipitation will fall as rain at lower elevations, saturating and weakening the upper snowpack. Watch out in steep and gullied terrain, where small avalanches can build and have severe consequences.

Travel and Terrain Advice
  • Use extra caution on slopes if the snow is moist or wet.
  • Use caution above cliffs and terrain traps where small avalanches may have severe consequences.
  • Best to avoid avalanche terrain during periods of heavy loading from rain.

Avalanche Summary

On Thursday, it was easy to initiate large wet loose avalanche in steep terrain below treeline. The avalanches were generally slow but ran far.

Snowpack Summary

Around 15 to 60 mm of rain fell on the snowpack up to around 1700 m on Thursday and Friday, with precipitation as snow above. More of the same is forecasted for Saturday. In alpine terrain, the snow will create new storm slabs. This snow overlies variable surfaces including crusts and facets, which are more likely to be problematic on shady aspects. The snowpack below this is generally strong.

At treeline and below treeline elevations, a spring snowpack exists. Rain is saturating and weakening the upper snowpack, allowing for loose wet avalanches. This wet snow may freeze overnight at higher elevations with cool temperatures. The mid and lower snowpack are strong.

Weather Forecast

SATURDAY: Cloudy with snow at higher elevations and rain below, accumulation 20 to 30 mm water equivalent, strong southerly winds, treeline temperature 3 C, freezing level 1600 m.

SUNDAY: Mostly cloudy with early-morning precipitation, accumulation 10 to 20 mm water equivalent, light westerly winds, alpine temperature 1 C, freezing level 1400 m.

MONDAY: Mostly cloudy, light southwesterly winds, alpine temperature 2 C, freezing level 1600 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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