Date issued

Jan 12, 2018 - 4:00 PM

Valid until

Jan 13, 2018 - 4:00 PM

Prepared by

tim haggarty

Be on your game for the weekend. Persistent slabs in exposed areas make it difficult to travel with confidence. Watch for increasing west winds that may further develop windslabs and rising temperatures that may allow for easier triggering.

Regular season
Saturday - January 13, 2018
Alpine

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.

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.

Below Treeline

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.

Sunday - January 14, 2018
Alpine

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.

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.

Below Treeline

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.

Monday - January 15, 2018
Alpine

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.

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.

Below Treeline

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.

Avalanche Problem 1: Persistent Slabs

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

New snow covers pockets of old slab sitting on weak, faceted snow that lacks strength, and may fail, to mid-pack depths. Treat all wind exposed areas with care but approach larger, uniform features and thin areas with caution.

Travel and Terrain Advice
  • Avoid shallow snowpack areas where triggering is more likely.
  • Carefully evaluate big terrain features by digging and testing on adjacent, safe slopes.

Avalanche Problem 2: Wind Slabs

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

The new snow has already formed thin, spotty slabs even with the limited amount of wind we have seen so far. These slabs sit on freshly buried, weak facets and surface hoar in some areas. Watch for these slabs to develop with more wind Saturday.

Travel and Terrain Advice
  • Watch for surface cracking and stiffer surface layers of snow.

Avalanche Problem 3: Loose Dry

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

New snow covers a facetted/weak upper snowpack in sheltered areas. Be cautious in very steep terrain and in confined features where a small sluff could build mass. Even light winds were triggering these events along alpine ridges Thursday.

Travel and Terrain Advice
  • Use caution above ledges and cliffs where small avalanches may have severe consequences.
  • The shallow, weakening snowpack makes for difficult trail breaking at low elevations.

Avalanche Summary

Yesterday, besides a few small windslabs and sluffs from alpine terrain, a sz 2 slab 20cm deep and 50m wide likely failed on the Dec 18 persistent layer. This shallow slab ran a few meters before stepping down another 40 cm (likely through weak facets to the November 27 midpack crust). All of this ran 70m to a cliff triggering a small slab below.

Snowpack Summary

10-15cm of recent snow has blown into thin windslabs TL and above. Old slabs 10-30cm deeper sit on a weak layer of facets or surface hoar TL and above. In sheltered areas this new snow sits a faceted upper snowpack at all elevations. A strong mid snowpack crust is providing strength but is weakening. The lower snowpack continues to lose strength.

Weather Forecast

A ridge will reach the coast Friday and bring warmer, moist air to the  Jasper region through the weekend. Alpine temperatures will be inverted and reach -6C on Saturday with a chance of a few flurries in the AM, watch for West winds to increase to 15km/h. An increase in the freezing levels to 2200m is called for Sunday as West winds to 20km/h.

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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