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Archived

Avalanche Forecast

Feb 3rd, 2017–Feb 4th, 2017
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Little Yoho.

There is a lot of uncertainty with the weather, including snowfall amounts, over the weekend. If significant snowfall arrives expect to see an increase in avalanche activity on the persistent layers.

Weather Forecast

A low over the coast is spreading a stream of moisture to the Southern Rockies while competing polar air overlies our forecast area. The amount of snow that arrives depends on which of these two air masses is the strongest and where the boundary between them ends up varying between 10 and 30cm. Temps and winds will be equally difficult to predict.

Snowpack Summary

Strong winds last weekend created extensive wind effect TL and above. A generally weak snowpack exists below 2000m. At 2000m there is about 140 cm with the Jan 17 surface hoar layer down 30cm. In the mid-pack, the Dec facets are around 20cm thick. Weak facets can also be found at the base of the snowpack associated with an ice crust.

Avalanche Summary

There was a small avalanche cycle last weekend from strong winds. The activity has slowed significantly due to decreased winds and cooling temperatures. No avalanches reported Thursday or Friday.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Saturday

Avalanche Problems

Persistent Slabs

The generally weak, facetted mid pack is producing moderate to hard shears. In the upper snowpack around treeline a buried layer of surface hoar produces variable shears. Slab development will make triggering these layers more likely this weekend.

  • Use conservative route selection, choose moderate angled and supported terrain with low consequence.
  • Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3