Avalanche Forecast

Issued: Feb 8th, 2013 9:11AM

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

swerner, Avalanche Canada

Cariboos.

Blue skies and fresh snow may tempt you into steeper and bigger terrain. Maintain a diligent approach to terrain selection to best manage the current conditions.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain for the entire period

Weather Forecast

A strong ridge of high pressure builds off the coast allowing a cool, dry NorthWest flow over the region with high diurnal variations. Scattered too few clouds with some light flurries will exist Saturday, otherwise some sunny alpine skies will prevail with more predominant sunny skies and warmer temperatures on Sunday. Ridgetop winds will blow light-moderate from the NorthWest. Treeline temperatures will hover near -4 rising to zero degrees on Sunday, and freezing levels rising to 1200 m in the afternoon.

Avalanche Summary

No new recent avalanche observations haver been reported. Over the past couple of days a widespread natural avalanche cycle occurred up to size 2.5 mostly on NE-E aspects above 2000 m. A large natural size 3 slab avalanche was also reported from a large uneven south facing slope. the suspected failure plane being the buried crust down 40-80 cm. Several skier triggered avalanches up to size 2 were initiated from a variety of aspects and elevations ranging from 155-2200 m.

Snowpack Summary

20-40 cm of new snow sits on wind slabs and recently buried surface hoar, sun crusts and facets that formed at the beginning of February. Old storm snow has settled into a dense slab that could be triggered by skiers or sledders and produce avalanches up to size 2.0. This slab sits on a persistent weak interface deeper (40-80 cm down) in the snowpack, comprising yet again of crusts, surface hoar and facets that were buried January 23rd. Use extra caution on large open slopes, cutblocks and convex rolls at and below treeline where buried surface hoar may be preserved.Wind slabs continue to develop and stiffen on lee slopes (N-SE) and behind terrain features like ridgelines and ribs.The mid-pack is generally well settled and strong. Average snowpack depth at treeline elevations is near 200 cm. Watch the duration and intensity of the sun in your local riding area, it may weaken the upper snowpack. Cornices have grown and could threaten the slopes below.

Problems

Persistent Slabs

New storm snow adds to the depth (50-80 cm) of the slab that is sitting on a variety of old surfaces comprising of surface hoar, crusts and facets. Persistent slabs continue to be reactive to rider triggers and can be difficult to predict.

Use extra caution on open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Good group management is essential to manage current conditions safely.>Whumpfing is direct evidence of a buried instability.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Old wind slabs continue to be a concern, and new wind slabs have formed. Concerning areas are on lee slopes and behind terrain features like ridges and ribs. They could be triggered under the weight of a person. Cornices may threaten slopes below.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Feb 9th, 2013 2:00PM