Avalanche Forecast

Sea To Sky

Date issued

Nov 28, 2017 - 4:05 PM

Valid until

Nov 29, 2017 - 2:00 PM

Prepared by

jfloyer

Successive storms will result in elevated danger, particularly in exposed, windy locations. There's a chance it may start to snow heavily a little earlier than expected on Wednesday. If so, adjust your objectives accordingly.

Regular season
Tuesday - November 28, 2017
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

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.

Wednesday - November 29, 2017
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.

Thursday - November 30, 2017
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.

Avalanche Problem 1: Storm Slabs

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

New storm slabs are building over a crust layer. This layer may slide easily, particularly on steep convex terrain or where the wind has blown it into more cohesive slabs.

Travel and Terrain Advice
  • The new snow will require several days to settle and stabilize.
  • Avoid steep lee and cross-loaded features

Avalanche Summary

Natural avalanches were reported up to size 2.5 on Sunday. Activity diminished on Monday following a drying and cooling trend, but is likely to pick up again, especially in steep, wind affected terrain for Tuesday.

Snowpack Summary

Approximately 20-30 cm new snow now sits on top of a rain crust (or multiple crusts) that formed during the recent wet weather. Strong winds have blown snow around in exposed areas creating drifts and scoured areas. Snowpack depths are typically around 140 cm in sheltered treeline locations, although deeper (and shallower) spots certainly exist on account of the strong winds.

Weather Forecast

A series of storms is expected to bring further snow and wind to this region.

Wednesday: Light snow during the day, getting heavier in the afternoon. Expect around 5 cm new snow during the day, then another 15-20 cm on Wednesday night. Freezing levels around 1100 m. Moderate westerly winds, becoming strong southwesterly later on.

Thursday: 5 cm or so new snow. Freezing levels around 1000 m. Moderate southwesterly winds.

Friday: 10-15 cm new snow. Freezing levels around 900 m. Strong southwesterly 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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