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Avalanche Forecast

Apr 21st, 2012–Apr 22nd, 2012
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
3: Considerable
The avalanche danger rating below treeline will be considerable
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
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
Below Threshold
The avalanche danger rating in the alpine will be below threshold
Treeline
Below Threshold
The avalanche danger rating at treeline will be below threshold
Below Treeline
Below Threshold
The avalanche danger rating below treeline will be below threshold

Regions: South Columbia.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Broken cloud is forecast for Sunday with a chance of light rainfall in the north of the region near Revelstoke. Light rainfall is forecast on Monday, once again, with the highest amounts occurring in the north. Freezing levels are expected to sit at about 3000m for both days with moderate and southwest ridgetop winds.

Avalanche Summary

Widespread loose and wind slab activity to size 2 was observed on Friday. I expect a shift to more widespread wet snow instabilities with warm temperatures forecast for Sunday and Monday.

Snowpack Summary

On Thursday night, light to locally moderate amounts of snow fell forming wind slabs that most likely settled considerably or turned to wet slabs with warming on Saturday. The recently fallen snow overlies well settled powder, melt-freeze crust sandwiches and wet grains at treeline and in the alpine while warm temperatures continue to penetrate and weaken the isothermal snowpack at lower elevations. The mid-February buried surface hoar layer is down about 140-220 cm. The likelihood of avalanches failing on this layer has been very low due to cooler temperatures, however it may wake up with warming and the consequence continues to be very large destructive avalanches. Cornices in the region are very large and have may become weak with spring temperatures.

Avalanche Problems

Loose Wet

Rising freezing levels and solar radiation will promote ongoing loose wet avalanche activity, particularly in steep terrain. Loose wet avalanches can be pushy and entrain mass quickly.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 5

Wet Slabs

Forecast warming will promote wet slab avalanche activity. In the upper snowpack, there are a variety of crusts that may act as a suitable sliding surface for wet slab avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Cornices

Forecast warm temperatures will weaken cornices. Cornices may be destructive by themselves, and may also trigger avalanches on the slope below.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 1 - 5