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Archived

Avalanche Forecast

Jan 29th, 2020–Jan 30th, 2020
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
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
4: High
The avalanche danger rating below treeline will be high

Regions: Little Yoho.

Extreme winds have have increased the avalanche activity in the forecast region. As the storm intensifies the avalanche danger will rise.

Weather Forecast

The first wave of the incoming Westerly flow starts Wednesday afternoon. We will see sustained strong to extreme winds through the forecast region and small inputs of snow (up to 5 cm). On Friday a second westerly flow will move in. Heavy precipe, extreme winds and and freezing levels to 2000m are forecasted for Saturday.

Snowpack Summary

There is 40-80 cm above the Dec 31 layer of facets, surface hoar and sun crust which produces test results in the hard range. The bottom layer of the snow-pack consists of weak facets and depth hoar, except for in deeper snow-pack areas (over 2m) where the basal facets are not as prominent.

Avalanche Summary

An increase in natural avalanche activity up to size 2.5 was observed Wednesday. This appeared to be a result of the strong to extreme winds starting late in the morning. With forecasted values of 100 kilometer an hour winds continuing through the weekend, we can expect more natural avalanche activity to come.

Confidence

Timing of incoming weather systems is uncertain on Friday

Avalanche Problems

Wind Slabs

Extreme wind values from the SW will load lee areas, especially in the alpine. With the intensity of the forecasted winds to continue through the weekend, expect windslab development at lower elevations.

  • If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 2

Persistent Slabs

The Dec 31 layer continues to be a concern. The layer can be found 50 to 80cm down showing varied results in snow pack test. With forecasted snow and wind over the next few days we will likely see an increase in avalanche activity on this layer.

  • Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Deep Persistent Slabs

Generally the snowpack in the Little Yoho region is deeper and these layers are not as distinct. It is still a good idea to be cautious with shallow snowpack areas and avoid thin spots.

  • Avoid shallow snowpack areas where triggering is more likely.
  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 2 - 3.5