Avalanche Forecast

Issued: Apr 4th, 2012 10:47AM

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

ccampbell, Avalanche Canada

Cariboos.

Summary

Confidence

Good

Weather Forecast

Thursday and Friday: unsettled conditions with isolated light flurries interspersed with intense sunshine. Freezing levels hovering around 1000m-1200m and light to moderate northerly ridgetop winds. Saturday: Mainly clear and dry with light winds and 1200m freezing levels.

Avalanche Summary

Observations from Tuesday are limited due to poor visibility. Reports include one natural cornice triggered Size 2.5, 100cm thick wind slab avalanche on a north aspect. One recent Size 3 glide slab avalanche was also observed on a south aspect at 1800m.

Snowpack Summary

Another 10-40cm during the day and overnight Tuesday added to the 30-60cm of recent storm snow. Sustained southeasterly through northeasterly winds contributed to continued wind slab formation at all elevations, as well as cornice development. Although generally settling and bonding well, recent snowpack tests on a north facing treeline slope resulted in easy to moderate shears down 25cm within the storm snow, and down 65cm on an underlying crust. Not only will daytime warming and sun-exposure cause surface snow to lose cohesion and cornices to weaken, they will also increase settlement rates and decrease slab stability.

Problems

Wind Slabs

Generally lurking below ridgecrests, behind terrain features, and in gullies. Thick fresh wind slabs are highly sensitive to human triggers and cornice falls, and sun-exposure is expected to make things even more touchy.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Cornices

Large and weak cornices could easily start popping off with sun-exposure. Not only are they a hazard in themselves, but can also act as a heavy trigger for very large avalanches on the slope below.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Loose Wet

Steep rocky terrain in the afternoon. Wet loose avalanches can entrain significant mass and run long distances.

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

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Apr 5th, 2012 9:00AM