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 and Cornices.

ccampbell, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Good

Weather Forecast

A ridge of high pressure is expected to keep the northwest ranges mainly sunny and dry with light winds throughout the forecast period. Freezing levels are expected to reach 1000m on Thursday afternoon, but Friday and Saturday should be colder with 500m freezing levels.

Avalanche Summary

Reports from Tuesday include evidence of a widespread natural cycle to Size 3 primarily due to wind-loading during Monday's storm. On Tuesday afternoon, sun-exposure caused numerous wet loose avalanches up to Size 2.0 involving the recent storm snow running on a sun crust. Large glide avalanche activity also continued on solar aspects.

Snowpack Summary

15-40cm of new snow is generally bonding well to the previous predominately crusty snow surface. However, sheltered shady slopes may be harbouring buried surface hoar and/or preserved old storm snow from last week, which isn't as stable. Furthermore, not only will daytime warming and sun-exposure cause surface snow to lose cohesion, 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 likely sensitive to human triggers and cornice falls, especially with warming and sun-exposure.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 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.

Likelihood

Possible - Likely

Expected Size

1 - 4

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