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Avalanche Bulletin - Waterton Lakes National Park

Issued Fri Apr 19, 2013 17:00
Valid Until Mon Apr 22, 2013 17:00

We are at the end of our regular forecast season however AVALANCHE HAZARD WILL PERSIST. Generally, hazard will be higher with heating from rain or sun and will be lowest during cool periods. Spring storms may also bring additional snow.

        

Danger Ratings: Saturday

alpine treeline below treeline alpine: N/A - No Rating, treeline: N/A - No Rating, below treeline: N/A - No Rating
alpine: N/A - No Rating
N/A - No Rating N/A
N/A
treeline: N/A - No Rating
N/A - No Rating N/A
N/A
below treeline: N/A - No Rating
N/A - No Rating N/A
N/A
Forecast Sunday Monday
alpine
 N/A - No Rating N/A - No Rating
treeline N/A - No Rating N/A - No Rating
below treeline N/A - No Rating N/A - No Rating

Weather Observations

Past 24 Hr WeatherLittle Prairie 1650m
Maximum (°C)6
Minimum (°C)0
Snowfall (cm)1
Snow Pack (cm)125
Wind speedModerate (26-40 km/h)
Ridgetop wind directionSW
Past 24 Hr WeatherLittle Prairie 1650m
Maximum (°C)6
Minimum (°C)0
Snowfall (cm)1
Snow Pack (cm)125
Wind speedModerate (26-40 km/h)
Ridgetop wind directionSW
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: Loose Wet

Which Elevation?

Which Elevation? treeline, below treeline, alpine

Which Slopes?

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

Chance of Avalanches?

Chance of Avalanches? likely

Expected Size?

Expected Size? small - large

Depending upon the inputs of heat from rain or sun this activity can be expected everywhere. Travelers must carefully monitor surface snow and be clear of slopes before crusts break down. Use extra caution if there is moist snow over buried crusts.

Travel and Terrain Advice

  • Be alert to conditions that change with elevation.
  • Plan to be off big slopes before the temperatures rises and the snowpack deteriorates.

Problem 2: Wind Slabs

Which Elevation?

Which Elevation? alpine, treeline

Which Slopes?

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

Chance of Avalanches?

Chance of Avalanches? possible

Expected Size?

Expected Size? small - large

There still remains some dry snow available for transport at upper elevations on some low angled slopes. Southwest winds have been redistributing this forming isolated pockets of slab. Additional snowfall may also contribute to the formation of these

Travel and Terrain Advice

  • Be cautious as you transition into wind affected terrain.
  • Caution in lee and cross-loaded terrain near ridge crests.

Problem 3: Cornices

Which Elevation?

Which Elevation? alpine, treeline

Which Slopes?

Which Slopes? northwest, north, northeast, east

Chance of Avalanches?

Chance of Avalanches? possible

Expected Size?

Expected Size? small - large

With warm temperatures, solar heating, or rain to upper elevations, cornice failures will occur. These are large triggers and have the potential to create larger avalanches. Minimize your exposure during rapid warming or loading.

Travel and Terrain Advice

  • Pay attention to overhead hazards like cornices.
  • Cornices become weak with daytime heating.
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