Avalanche Forecast

Issued: Apr 21st, 2012 10:08AM

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

Kootenay Boundary.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Mostly clear skies are expected for Sunday and Monday. Freezing levels are expected to reach 3300m with moderate alpine winds from the southwest.

Avalanche Summary

No new avalanches have been reported from the region. This may speak more to the lack of professional observers at this time rather than actual conditions. I would expect wet natural avalanche activity on Sunday and Monday resulting from forecast rising freezing levels and solar input.

Snowpack Summary

Recently formed windslabs have most likely settled and gained considerable strength with the warm temperatures on Saturday, and in some places transitioned into wet slabs. Below this, spring weather has left us with wet grains or melt-freeze crusts at treeline and above while warm temperatures have 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 rocky, sun-exposed slopes. Loose wet avalanches can accelerate and entrain mass quickly.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely - Certain

Expected Size

1 - 5

Wet Slabs

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 6

Cornices

Rising freezing levels will weaken cornices. They can be destructive by themselves and can also trigger large avalanches on the slope below.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 5

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