Avalanche Forecast

Issued: Apr 22nd, 2012 4:00PM

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 Wind Slabs.

triley, Avalanche Canada

Cariboos.

Summary

Confidence

Fair - Due to limited field observations on Monday

Weather Forecast

Precipitation is expected to increase during the day on Sunday with about 3-5 mm forecast by Monday morning. Winds are expected to increase to moderate from the southwest, and the freezing level is expected to rise to about 2300 metres on Sunday and drop to 2000 metres by Monday morning.

Avalanche Summary

Natural moist and wet loose snow avalanches were reported from Friday up to size 2.0, some wet slab avalanches were also reported. Moist and wet loose avalanches continued to release on Saturday from solar exposed aspects.

Snowpack Summary

On Thursday, moderate to locally heavy accumulations formed wind slabs at treeline and above on a variety of temperature-affected surfaces that include well settled powder, wet grains and crust sandwiches. 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, although avalanches releasing on this layer represent an extremely low probability-high consequence scenario. Cornices in the region are very large. With spring temperatures, and direct solar radiation these are more likely to become weak and fail. They could provide a large enough trigger to release deep layers on slopes below. Average snowpack depth in the alpine remains in the 3 m range.

Problems

Loose Wet

Snow stability can deteriorate very quickly with spring temperatures. Watch for loose wet avalanches on steep terrain, especially if the sun is shining, or if the rain persists.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Wet Slabs

Buried crusts will provide an ideal sliding layer for wet slabs, especially on sun-exposed slopes. Warmer temperatures at lower elevations are also a contributing factor. Spring temperatures will also promote glide crack activity.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Wind Slabs

New windslabs may develop due to forecast snowfall and southwest winds. Recent windslabs may not have bonded on some high alpine northerly aspects.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Apr 23rd, 2012 9:00AM