Avalanche Forecast

Issued: Dec 6th, 2012 9:57AM

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

mbender, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Poor - Due to limited field observations for the entire period

Weather Forecast

Friday: Broken clouds with some sunny breaks, ridgetop winds west 15 km/hr, and alpine temperatures near -10. Saturday: Increasing clouds as a warm front approaches. Periods of snow will begin in the evening. Winds west and northwest 30-50km/h. Temperatures near -8 in the alpine. Sunday: Light to moderate amounts of precipitation. Winds southwest 40km/h. Temperatures in the alpine -3.

Avalanche Summary

Recent reports indicate natural avalanches to size 1.5. These been running in the most recent storm snow.

Snowpack Summary

Up to 60 cm of new storm snow has fallen over the region in the past 4 days. Recently formed and buried windslabs continue to dominate the upper snowpack. Test results show an easy resistant shear down 30-35 cm and a hard resistant down 80 cm. The mid-pack is gaining strength and is well settled.Digging down deeper, there is an early November facet/crust layer, which sits near the base of the snowpack. Tests done in the Bear Pass area around 1100 m have shown this layer to be unreactive. Testing done in the Shames area on this interface have also shown no results, with moist snow below.Total snowpack depth above 1000 m is 150-200 cm deep. Below 1000 m the snowpack shows a sharp transition from 100 cm dropping to 50 cm, and is generally below threshold.

Problems

Wind Slabs

Winds shifting in direction over the past 5 days have created windslabs on a variety of aspects.

Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid travelling in areas that have been reverse loaded by winds.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

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

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

2 - 6

Valid until: Dec 7th, 2012 2:00PM