Avalanche Forecast

Issued: Apr 20th, 2012 10:21AM

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

jlammers, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Saturday: Clear skies / light to moderate southwest winds / freezing level at 2300m Sunday: Mostly clear / strong southwesterly winds / freezing level at about 3300m Monday: mostly clear / strong southwest winds / freezing level at about 3200m

Avalanche Summary

No new avalanches have been reported from the region. This may speak more to the number of professional observers at this time rather than actual conditions. I would expect human and naturally triggered wind slab avalanches in the wake of Thursday's storm, with ongoing activity resulting from warming and solar input forecast for Saturday.

Snowpack Summary

Significant windslabs that formed Thursday night now overlie light amounts of temperature-affected snow that fell over the last week. Below this, spring weather has left us with wet grains or melt-freeze crusts at treeline and above while rain has continued 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

Watch for loose wet avalanche activity on steep terrain, particularly on sun-exposed slopes. Loose wet avalanches can accelerate and entrain mass quickly.

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

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 5

Wind Slabs

Fresh windslabs exist in lee terrain at treeline and in the alpine. Windslabs may weaken with warm temperatures forecast for the weekend.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Wet Slabs

As warm temperatures continue to penetrate the snowpack, wet slabs become more probable. Recently buried crusts and other deep weaknesses may provide suitable sliding layers for wet slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 6

Valid until: Apr 21st, 2012 9:00AM