Avalanche Bulletin - Jasper National Park - Mon Jan 16, 2012

Issued: Mon Oct 07, 2019 18:49
Valid Until: further notice

Winter has sprung: Avalanche season is here in the Alpine. Glacier travel is also at its trickiest. Use our Weather Stations, and the ACMG's MCR for conditions; talk to people who have been out recently; or ask for Visitor Safety at 780-852-6155. [RM]

Public Avalanche Forecast
Early Season Conditions:  Monday
Early Season Conditions

Insufficient observations exist to reliably rate the avalanche danger. Expect shallow snow cover with thinly buried rocks and trees just beneath the surface. Avalanche danger often concentrates in gullies and other deposition areas, where windslabs may bond poorly to a weak underlying base. Deeper snow usually exists at higher elevations.

Past 24 hour weather
Station Maximum (°C) Minimum (°C) Snowfall (cm) Snow Pack (cm) Wind speed Ridgetop wind direction
Columbia Icefields area Not Available Not Available Not Available Not Available Not Available Not Available
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.
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.
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.
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.
Extreme
  • Avoid all avalanche terrain.
  • Natural and human-triggered avalanches certain.
  • Large to very large avalanches in many areas.

Problem 1: Wind Slabs

Which Elevation?
Which Elevation? alpine
Which Slopes?
Which Slopes? north, northeast, east, southeast, south, west, southwest, northwest
Chance of Avalanches?
Chance of Avalanches? possible
Expected Size?
Expected Size? small - large

These have caught scramblers in places like the West bowl on Cavell, & alpine climbers on routes like Side Street. Hikers: avalanche hazard may exist on the Skyline trail. Ice climbers: consider overhead slopes, and wind-loaded slopes on approaches.

Travel and Terrain Advice

  • Give cornices a wide berth when traveling on or below ridges.
  • Use caution in lee and cross-loaded areas. Recent wind loading has created new wind slabs.

Problem 2: Wet Loose

Which Elevation?
Which Elevation? alpine
Which Slopes?
Which Slopes? west, southwest, south, southeast, east
Chance of Avalanches?
Chance of Avalanches? possible
Expected Size?
Expected Size? small - large

Sun, or fluctuating freezing levels can rapidly transform cold powder snow into moist mush. When this happens, natural avalanches will run in steep solar terrain. Avoid climbs with overhead hazard, or in gullies, when sun or soaring temps threaten.

Travel and Terrain Advice

  • Consider the consequences of a small avalanche, with thin snow barely covering rocks, etc.
  • Minimize exposure to sun exposed slopes when the solar radiation is strong.

Problem 3: Dry Loose

Which Elevation?
Which Elevation? alpine
Which Slopes?
Which Slopes? north, northeast, east, northwest
Chance of Avalanches?
Chance of Avalanches? possible
Expected Size?
Expected Size? small - small

Recent snow and wind increase frequency of loose dry sluffs in steep, shaded terrain. With early season ice pro sometimes scarce, and tenuous pick placements, climbers should consider the risks of a sluff-induced fall if tapping up early season ice.

Travel and Terrain Advice

  • Use caution above cliffs where small avalanches may have severe consequences.
  • Be careful of loose dry power sluffing in steep terrain.
Problem Glossary
Dry Loose
  • Are usually small, but may gain significant mass on long steep slopes.
  • Are typically limited to steep terrain (40+ degrees).
  • Stabilize soon after a storm, usually within a few days.
Dry Loose avalanches are best managed by:
  • Avoiding terrain traps and large steep slopes until the surface has stabilized.
  • On large steep slopes, occasionally move across the fall line to avoid being caught by your own sluffs from above.
Wet Loose
  • Are more powerful than dry loose avalanches due to their higher density.
  • Are often limited to sunny slope aspects.
  • Are commonly confined to the warmest part of the day.
Wet Loose avalanches are best managed by:
  • Avoiding start zones and avalanche paths when the snow becomes moist from daytime heating, from rain, or does not freeze overnight.
Wind Slabs
  • Vary in size from small to medium.
  • Occur on steeper lee and cross-loaded portions of slopes (typically 35+ degrees).
  • Are often limited to specific terrain features such as lee ridge-tops.
  • Can often be recognized by the appearance of the snow surface, changes in surface snow hardness, hollow, drum-like sounds and/or shooting cracks.
  • Winds that vary in strength and direction can produce complex and unexpected wind slab patterns.
  • Stabilize fairly soon, usually in a few days to a week.
Wind slabs are best managed by:
  • Recognizing and avoiding areas where wind slabs have formed, until they have stabilized.
Storm Slabs
  • Vary in size from small to very large.
  • May be soft slabs, fooling people into underestimating slab potential.
  • Tend to occur on moderately steep slopes (35+ degrees).
  • May occur in all terrain, but are larger and more frequent in the alpine.
  • Stabilize soon after a storm, usually within a few days.
Storm slabs are best managed by:
  • Conservative terrain choices during and after storms until the storm snow has stabilized.
Wet Slabs
  • Involve wet layers in the snowpack, typically including deeper layers.
  • Tend to be large.
  • Occur when water forms or penetrates below the surface of the snowpack.
Wet slabs are best managed by: 
  • Avoiding start zones and avalanche paths when the snow becomes wet from daytime heating, rain, or lack of an overnight freeze.
Persistent Slabs
  • Slide on buried persistent weak layers, which often form during clear periods and may involve deeper layers from multiple storms.
  • Vary in size from medium to very large and may cross terrain barriers to involve multiple slide paths.
  • May occur on very gentle terrain, even slopes of 20 degrees or less.
  • May be localized to specific elevations, aspects, or regions.
  • There are often no visible signs of persistent slab instability.
  • Lack of avalanche activity and lack of danger signs are NOTreliable indicators of stability.
  • Compression tests and Rutschblock tests may locate persistent weak layers.
  • Stabilize slowly, tending to persist for several weeks or longer.
  • Often have dormant periods, becoming active again when the weather changes.
  • Are prone to lingering pockets of instability that persist long after most areas have stabilized.
  • Tend to release above the trigger, making it difficult to escape.
  • Are often triggered remotely from a long distance away.
Persistent slabs are best managed by:
  • Very conservative terrain choices.
  • Allow extra time for persistent slabs to stabilize and use a very cautious approach to new terrain. Be especially cautious after storms or during warming periods.
Deep Persistent Slabs
  • Slide on deeply buried persistent weak layers, which often form during clear periods or rain-on-snow events early in the season.
  • Involve thick, hard slabs, sometimes the entire snowpack.
  • Tend to be very large, commonly cross terrain barriers to involve multiple slide paths.
  • Tend to occur on larger slopes of moderate steepness, typically 30-40 degrees.
  • May be localized to specific elevations, aspects, or regions.
  • There are often no visible signs of persistent deep slab instability.
  • Lack of avalanche activity and lack of danger signs are NOT reliable indicators of stability.
  • Stabilize slowly if at all, persisting for months and often the entire season.
  • Dormant persistent deep slab instabilities often become active again when the weather changes, especially after storms or with warm spring weather.
  • Tend to release above the trigger, making it difficult to escape.
  • Are often triggered remotely from a long distance away.

Deep persistent slabs are best managed by:

  • Very conservative terrain choices and a very cautious approach to new terrain.
  • Be especially cautious after storms or during warming periods.
Cornices
  • May trigger large slab avalanches on relatively stable slopes below.
  • Are often associated with recent wind loading and/or temperature changes.
  • Can be triggered from ridges, sometimes breaking surprisingly far back onto ridge tops.

Cornices are best managed by:

  • Approaching corniced ridges cautiously.
  • Avoid travelling on or near overhanging cornices and limit time spent exposed to slopes below cornices, especially soon after wind events and during periods of warming temperatures.
Forecast Details

Weather Forecast

Expect the current alternation of cold fronts and sunny spells to continue. Watch out if fluctuating freezing levels, or rain, leave crusts - these may act as sliding layers down the road. Avalanche Canada offers a regional forecast (https://www.avalanche.ca/weather/forecast). Detailed local forecasts are available on SpotWX (https://spotwx.com/)

Snowpack Discussion

An Autumn overview: (https://www.avalanche.ca/early-season-conditions).

Currently, Alpine areas above threshold for avalanches are widespread West of the 93N, but only isolated to the East. Many open crevasses are hidden by thin bridges of wind-blown snow. Roping up, diligent probing, and glacier reading experience are critical for glacier travel.

Avalanche Activity Discussion

Danger is highest after new snowfall, rain, or wind transport - expect increased avalanche activity during, & for 24 hrs after such events. Use extra caution where slabs lie over alpine ice -this surprised climbers on Mt Athabasca last year. Tis' the season: do your own avalanche forecasting; carry a transceiver, shovel & probe; and practice.

For More Details

Emergency: 1 (877) 852-3100
Forecasters: (780) 852-6155

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