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Archived

Avalanche Forecast

Feb 11th, 2020–Feb 12th, 2020
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Kananaskis.

Very strong and highly variable winds have changed the picture in the Alpine. Be aware of fresh wind slabs on several different aspects.

Confidence

High -

Weather Forecast

Flurries will end Tuesday evening, with clearing skies arriving on Wednesday. The morning will be cold with temps near -21, but expect -6 by late afternoon. Winds will diminish in speed through the night with only light NW winds expected for most of Wednesday.

Avalanche Summary

Isolated small sluffs in very steep Alpine terrain due to the strong winds. In addition, 2 new slab avalanches were noted today.

1. On a NE aspect at 2400m a naturally triggered shallow wind slab ran for approximately 80m before stepping down to the basal layers. This resulted in a size 2.0 full-depth avalanche.

2. In very steep Alpine terrain on an E aspect a size 1.5 naturally triggered wind slab was observed on the Goat Range.

Snowpack Summary

Trace to 3cm of new snow, brings recent storm snow totals to around 15cm at Treeline. Below 2300m this recent snow remains low density. However, in the Alpine a wide variety of wind slab depths and densities dominate the landscape, from recent strong and gusty NW/W/SW winds. Forecasters experienced some cracking today in wind effected terrain. These surface layers overlie a number of generations of previously formed wind slabs in the Alpine and at Treeline. Near valley bottom the buried rain crust from earlier in the month continues to hold the weight of a skier. Overall, the snowpack has a well settled and strong midpack, but the basal weaknesses persist, particularly in shallow snowpack regions. 

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be careful as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
  • Avoid shallow snowpack areas, rock outcroppings and steep convex terrain where triggering is most likely.

Avalanche Problems

Wind Slabs

Strong to extreme NW/W/SW winds have created a variety of wind slab conditions. In some areas these slabs will be sensitive to human triggering.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1.5 - 2.5

Deep Persistent Slabs

The weak basal layers are still a concern. An avalanche that occurred in the past 24 hours was a slide that stepped down to the basal layers and involved the entire snowpack. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3.5