[SS]

Avalanche Bulletin - Banff, Yoho and Kootenay National Parks

Issued Fri Mar 07, 2014 19:43
Valid Until Sat Mar 08, 2014 17:00
Several skier triggered avalanches over the past 3 days size 2-2.5 in KNP and Sunshine area, see the forecast details. Stick to conservative lines without over head hazard. LP

        

Danger Ratings: Saturday

alpine treeline below treeline alpine: 4 - High, treeline: 4 - High, below treeline: 3 - Considerable
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: 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...
below 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...
Forecast Sunday Monday
alpine
4 - High 3 - Considerable
treeline 4 - High 3 - Considerable
below treeline 3 - Considerable 3 - Considerable
Confidence: Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Observations

Past 24 Hr WeatherN Kootenay 1985/2405mBow Summit 2000mSunshine 2200m
Maximum (°C)11-1
Minimum (°C)-3-11-4
Snowfall (cm)1163
Snow Pack (cm)218153173
Wind speedNot AvailableModerate (26-40 km/h)Light (1-25 km/h)
Ridgetop wind directionNot AvailableSWW
Past 24 Hr WeatherN Kootenay 1985/2405mBow Summit 2000mSunshine 2200m
Maximum (°C)11-1
Minimum (°C)-3-11-4
Snowfall (cm)1163
Snow Pack (cm)218153173
Wind speedNot AvailableModerate (26-40 km/h)Light (1-25 km/h)
Ridgetop wind directionNot AvailableSWW
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: Persistent Slabs

Which Elevation?

Which Elevation? treeline, alpine, below treeline

Which Slopes?

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

Chance of Avalanches?

Chance of Avalanches? likely - very Likely

Expected Size?

Expected Size? small - large
This layer is especially touchy around Sunshine and in Kootenay on steep features at treeline and below. There have been several skier triggered avalanches to size 2 in past 36 hours and explosive triggered avalanches to size 3 today.

Travel and Terrain Advice

  • Avoid open slopes with any steepness over 30 degrees.
  • Avoid steep, open glades in the forest.

Problem 2: Wind Slabs

Which Elevation?

Which Elevation? alpine, treeline

Which Slopes?

Which Slopes? southeast, east, northeast, north

Chance of Avalanches?

Chance of Avalanches? possible - likely

Expected Size?

Expected Size? small - large
There are thin windslabs from the last storm on lee features that are reactive to explosives (size 1-2). Expect new windslabs to develop with incoming snow and wind over the weekend.

Travel and Terrain Advice

  • Be cautious as you transition into wind affected terrain.
  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.