Avalanche Forecast

Issued: Nov 30th, 2012 8:40AM

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

swerner, Avalanche Canada

Northwest Inland.

Limited field observations and reports exist from this region. Conditions can be variable. It is important to be familiar with the snowpack and avalanche problems that may exist in your local mountains.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

The weather pattern continues with generally cloudy skies, light amounts of precipitation, light winds and cool air. The arctic air mass that has been stationary over the Northern part of the province will slowly start to retreat Sunday afternoon bringing temperatures back to seasonal norms. Freezing levels will remain at valley bottom.Saturday: Snow amounts 5 cm, ridgetop winds SE 20 km/hr, alpine temps near -9.Sunday: Snow amounts near 5 cm, ridgetop winds SE 25 km/hr, and alpine temps - 7.Monday: Snow amounts near 5 cm, ridgetop winds SE 20 km/hr, and alpine temps 10.

Avalanche Summary

No new natural avalanches have been reported. Fresh wind slabs have been observed in exposed areas.

Snowpack Summary

New storm slabs and wind slabs instabilities exist at treeline and alpine locations. They may be touchy to rider triggers; especially on leeward slopes and behind terrain features where pockets of wind slab easily build. At treeline depths in the southern part of the region range between 70 â€“ 125 cm, but highly variable in the alpine with deep wind drifts and scoured slopes in exposed areas. Generally, the mid-pack is gaining strength and possibly even bridging the persistent weakness below. Digging down deeper is the early November facet/crust layer. This crust sits near the base of the snowpack down 70-110 cm. This layer has produced moderate "drops" results in recent snowpack tests. Because this weakness is so close to the ground in most areas, associated avalanche activity will likely be limited to slopes with smooth ground cover (e.g. scree slopes, rock slabs, grassy areas, etc.)

Problems

Storm Slabs

Natural avalanche activity is possible with continued loading from snow and wind. Rider triggering is likely, especially on steep convex slopes. Expect to find wind slabs below ridgecrests, behind terrain features, and in cross-loaded gullies.

Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Basal facet/crust weaknesses are often prone to remote triggering and step down avalanches, and typical trigger points include thin rocky areas. They may be difficult to trigger, but deep persistent slab avalanches are often very large.

Be aware of thin areas that may propagate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Dec 1st, 2012 2:00PM