Avalanche Forecast

Purcells

Date issued

Dec 2, 2017 - 4:45 PM

Valid until

Dec 3, 2017 - 2:00 PM

Prepared by

shorton

Snow from recent storms will remain reactive on wind-loaded terrain features.

Regular season
Saturday - December 2, 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.

Sunday - December 3, 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.

Monday - December 4, 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: Wind Slabs

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

Wind and snow has formed small reactive wind slabs on the downwind side of ridges and gullies.

Travel and Terrain Advice
  • Be cautious as you transition into wind affected terrain.
  • Watch for signs of instability such as whumpfing, cracking or recent natural avalanches.

Avalanche Summary

On Saturday, several size 1 wind slabs were triggered with explosives in the Golden and Invermere areas. There are no recent reports of natural or human triggered avalanches, but observations are limited. Please submit to the Mountain Information Network (MIN).

Snowpack Summary

Recent storms delivered 20-40 cm, with deeper wind deposits at higher elevations. The new snow sits above various crusts and moist snow left over from the warm weather in late November. Two deeper layers have been reported including the November 10 surface hoar layer down 80 cm and the Halloween crust down 100 cm. Information on the reactivity of these layers is limited. The average snow depth is over 150 cm in the alpine, 80-150 cm at treeline, and decreases rapidly below treeline where the primary hazards are rocks, stumps, and open creeks.

Weather Forecast

SUNDAY: 4-8 cm of snow overnight then gradual clearing throughout the day, light northwest wind, alpine temperatures around -10 C.

MONDAY: Mix of sun and cloud, light to moderate northwest wind, alpine temperatures around -10 C.

TUESDAY: Mostly sunny, light wind, alpine temperatures warming to -7 C.

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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