Avalanche Forecast

Issued: Apr 21st, 2012 10:05AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Loose Wet, Wet Slabs and Cornices.

jlammers, Avalanche Canada

South Columbia.

Summary

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.

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

Valid until: Apr 22nd, 2012 9:00AM