Archived

Avalanche Forecast

Dec 1st, 2011–Dec 2nd, 2011

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Coast.

Confidence

Fair - Due to limited field observations

Weather Forecast

A weak cold front should cross the region overnight on Thursday bringing gusty NW winds and a chance of light precipitation. The freezing level should drop to around 300m. The ridge of high pressure rebounds on Friday bringing dry and mainly sunny conditions to the South Coast for the next few days. We could see a temperature inversion develop by the weekend with highs of 5 or 6 degrees between 1500 and 2500m on Saturday, and 1500 and 3000m on Sunday.

Avalanche Summary

No new reports of avalanche activity in the region. Although it may be harder to trigger some of the deeper weaknesses in the snowpack, if you do, the resulting avalanche could be very large and destructive.

Snowpack Summary

Up higher, wind slabs and lingering storm snow instabilities still exist. There is a solid rain crust, down 15-30cm below 1800m, which has greatly reduced the likelihood of avalanches at lower elevations. A surface hoar layer has been observed down approximately 45cm in the Duffey Lake area. A facet layer near the base of the snowpack continues to give sudden collapse, ("drops") results in snowpack tests. Continued caution is recommended in shallow snowpack areas (lots of rocks or small trees poking through), especially on sun exposed slopes if the sun has any kick, and on any slope that has not recently released.

Avalanche Problems

Wind Slabs

Reverse loading is possible with forecast NW winds late Thursday and Friday. Watch for hard or soft wind slabs in exposed terrain on a variety of different aspects.

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3

Persistent Slabs

Weak layers of facets and depth hoar may be lurking deep in the snowpack. Be very cautious in shallow snowpack areas where triggering deeper weaknesses is more likely.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 5