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Avalanche Forecast

Jan 27th, 2016–Jan 30th, 2016
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Waterton Lakes.

The potential for buried persistent weak layers to have created a low probability/high consequence avalanche problem makes for decreased confidence.  Evaluate the snowpack and terrain carefully before exposing yourself to larger features.

Weather Forecast

Ongoing chinook winds (strong to extreme from the west) and warm temperatures (highs of 10 deg for the townsite and freezing levels as high as 2100m) will begin to abate Thursday afternoon, as the trailing end of a cold front brings increasing cloudiness, cooling temperatures and light precipitation to the area through Friday.

Snowpack Summary

Strong to extreme chinook (westerly) winds continue to build windslabs in lees and windpressed surfaces in exposed areas. These windslabs are stubborn to trigger but may propagate widely if they initiate on/step down to previously buried weak layers; a Jan 4th crust/surface hoar (solar/shady aspects) down 40-70cm, and a Dec 9th crust down 70-120cm.

Avalanche Summary

A few isolated large avalanches were observed locally last weekend, these are suspected to have been persistent slabs failing on the Jan 4 crust/surface hoar layer. Neighboring ski operations have been reporting isolated large persistent slab avalanches failing on the Dec. 9th crust.

Confidence

Freezing levels are uncertain

Avalanche Problems

Wind Slabs

While stubborn to trigger, windslabs have the potential step down to previously buried weak layers.
If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid steep lee and cross-loaded slopes

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1 - 2

Persistent Slabs

A weak layers buried in early January and early December have not been ruled out as the potential failure plane of several large, recent slab avalanches. While the probability of triggering these layers is low, the consequences will be significant.
Assess start zones carefully and use safe travel techniques.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely

Expected Size: 1 - 3

Loose Wet

Use caution above cliffs where small avalanches may have severe consequences.

Aspects: North, North East, East, South East, South.

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 1