Avalanche Forecast

Issued: Apr 20th, 2012 10:22AM

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

South Columbia.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Saturday: Clear skies / light to moderate southwest winds / freezing level at 2000m Sunday: Light precipitation / strong southwesterly winds / freezing level at about 2800m Monday: light precipitation / strong southwest winds / freezing level at about 2800m

Avalanche Summary

Over the last few days, mostly loose wet avalanches to size 2 were reported in steep, sun-exposed terrain. Watch for continued wind slab activity as a result of Thursday night's storm as well as wet avalanche activity with warming forecast for the weekend.

Snowpack Summary

On Thursday night significant windslabs formed at higher elevations and now overlie light to locally moderate amounts of well-settled, temperature-affected snow that fell over the last week. Below the recent snow, spring weather has left us with a crust or wet grains 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

Spring temperatures will promote ongoing loose wet avalanche activity, particularly in steep terrain. Loose wet avalanches can be heavy and entrain mass quickly.

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

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 5

Wind Slabs

Newly formed wind slabs may not bond well to melt-freeze crusts where they exist and may weaken with warming forecast for the weekend. Watch for triggering in gullies, over steep rolls and behind ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Wet Slabs

Buried crusts provide an ideal sliding layer for wet slabs, especially on sun-exposed slopes or with warmer temperatures at lower elevations. Destructive glide cracks are also releasing regularly at this time.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 6

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