Date issued

Jan 29, 2018 - 4:08 PM

Valid until

Jan 30, 2018 - 4:00 PM

Prepared by

max darrah

Rapid loading on top of persistent weak layers is expected to create dangerous avalanche conditions over the next few days.

Closures of HW 93 (Icefield Parkway) will be in effect starting Jan 29 for control work.

511.Alberta.ca for updated  info.

Regular season
Monday - January 29, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Tuesday - January 30, 2018
Alpine

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.

Treeline

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.

Below Treeline

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.

Wednesday - January 31, 2018
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

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.

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?

Incoming new snow and wind will build fresh storm slabs.

Travel and Terrain Advice
  • Minimize overhead exposure during periods of heavy loading from new snow, wind.
  • The new snow will require several days to settle and stabilize.

Avalanche Problem 2: Persistent Slabs

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

This problem is made up of 3 significant interfaces in the upper snowpack. Incoming new snow may overload these layers, which have recently been reactive to skier testing and explosive control work, producing a few very significant results.

Travel and Terrain Advice
  • If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
  • Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Avalanche Problem 3: Loose Dry

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

Watch for sluffing in steep terrain.

Travel and Terrain Advice
  • The volume of sluffing could knock you over; choose your climb carefully and belay when exposed.

Avalanche Summary

Avalanche control on Parkers Ridge Friday produced 2 large avalanches, size 2 and 3 on a NE aspect running as a persistent slab. Numerous sloughs observed today from steep rocky terrain.

Snowpack Summary

Incoming new snow is building fresh storm slabs and is falling on a persistent slab made up of 3 weak interfaces in the top 30 to 50cm of the snowpack. Depth and distribution of these weak surface hoar/facet layers varies within the terrain; although buried surface hoar has consistently been found in sheltered features at TL.

Weather Forecast

Heavy snowfall Monday night, with amounts between 20-40cm possible for the Columbia Icefields area. Moderate SW winds to accompany this snowfall. Pressure rising mid-week as precipitation tapers. Temperatures will drop later in the week as an Arctic ridge establishes itself along the Eastern slopes of the Rockies.

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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