[SS]

Avalanche Bulletin - Banff, Yoho and Kootenay National Parks

Issued Wed Nov 26, 2014 17:00
Valid Until Thu Nov 27, 2014 17:00
The first big storm of the winter is beginning now, along with the first avalanche cycle of the winter for Thursday and Friday. Ice climbers should stay away from avalanche gullies, and skiers be aware that the snowpack is weak and unstable. GS

        

Danger Ratings: Thursday

alpine treeline below treeline alpine: 4 - High, treeline: 3 - Considerable, below treeline: 1 - Low
alpine: 4 - High
4 - High Very dangerous avalanche conditions. Travel in avalanche terrain not recommended.
  • 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.
More...
treeline: 3 - Considerable
3 - Considerable Dangerous avalanche conditions. Careful snowpack evaluation, cautious route-finding and conservative decision-making essential.
  • 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.
More...
below treeline: 1 - Low
1 - Low Generally safe avalanche conditions. Watch for unstable snow on isolated terrain features.
  • 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.
More...
Forecast Friday Saturday
alpine
4 - High 3 - Considerable
treeline 3 - Considerable 2 - Moderate
below treeline 1 - Low 1 - Low
Confidence: Good

Weather Observations

Past 24 Hr WeatherSimpson 2115/2320mBow Summit 2040mSunshine 2200m
Maximum (°C)-9-8-8
Minimum (°C)-10-10-14
Snowfall (cm)1121
Snow Pack (cm)904866
Wind speedLight (1-25 km/h)Light (1-25 km/h)Light (1-25 km/h)
Ridgetop wind directionSSS
Past 24 Hr WeatherSimpson 2115/2320mBow Summit 2040mSunshine 2200m
Maximum (°C)-9-8-8
Minimum (°C)-10-10-14
Snowfall (cm)1121
Snow Pack (cm)904866
Wind speedLight (1-25 km/h)Light (1-25 km/h)Light (1-25 km/h)
Ridgetop wind directionSSS
Low Moderate Considerable High Extreme
  • 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.
  • 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.
  • 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.
  • 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.
  • Avoid all avalanche terrain.
  • Natural and human-triggered avalanches certain.
  • Large to very large avalanches in many areas.

Problem 1: Storm Slabs

Which Elevation?

Which Elevation? alpine, treeline

Which Slopes?

Which Slopes? north, northeast, east, southeast, northwest

Chance of Avalanches?

Chance of Avalanches? possible - likely

Expected Size?

Expected Size? small - large
Weak layers formed during this storm will create avalanche issues at and near the storm snow interface. Watch for slabs in all leeward areas in addition to loose snow avalanches in gullies. Ice climbers should limit their exposure.

Problem 2: Deep Persistent Slabs

Which Elevation?

Which Elevation? alpine, treeline

Which Slopes?

Which Slopes? north, northeast, east, southeast, south, southwest, west, northwest

Chance of Avalanches?

Chance of Avalanches? possible - likely

Expected Size?

Expected Size? small - large
The new snow will overload a very weak base and cause avalanches running on the ground. Getting caught in an avalanche like this will result in an awful ride through trees and rocks. Avoid all open avalanche terrain during this storm.