Avalanche Forecast

Issued: Apr 5th, 2012 10:24AM

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

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 1500m during the day, but drop back down to sea level at night.

Avalanche Summary

Reports from Wednesday include wet loose avalanche activity up to Size 2.0 in response to direct sun exposure. Cornices have also been failing over the past couple of days, some of which triggered wind slab avalanches up to Size 2 on the slope below. Large glide avalanche activity also continued on solar aspects.

Snowpack Summary

15-40cm of new snow is settling and faceting, and 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. 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

Loose Wet

Steep sun-exposed slopes in the afternoon. Although generally slow moving and in extreme cliffy terrain, wet Loose avalanches can entrain significant mass and have dire consequences if terrain traps are in the runout.

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

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

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

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: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 5

Valid until: Apr 6th, 2012 9:00AM