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Archived

Avalanche Forecast

Nov 25th, 2012–Nov 26th, 2012
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

This bulletin is based on limited data. Local variations in conditions are likely to exist. Check out the forecaster's blog for further details on interpreting early season bulletins.

Confidence

Poor - Due to limited field observations

Weather Forecast

Synopsis: A ridge of high pressure over southern BC should result in drier conditions and partial clearing for the northwest on Monday and Tuesday. The ridge should break down on Wednesday allowing a frontal system to push in. Monday: Cloudy with sunny breaks. Freezing level around 500 m. Winds are light and variable. Tuesday: Cloudy with sunny breaks. Freezing level at around 500 m. Winds light from the northwest. Wednesday: Increasing cloud with precipitation developing. Freezing level around 300-400 m.

Avalanche Summary

Observations are limited; however, it is likely that a natural avalanche cycle occurred at sometime in the past 48 hours. One observer reported ski cutting a couple size 1 avalanches in the Shames backcountry on Saturday. Natural avalanche activity should taper off early this week, but storm snow instabilities and weak wind slabs may still be susceptible to human triggering.

Snowpack Summary

60-80 cm of storm snow fell in the past few days, accompanied by shifting south to northwest winds. Weaknesses may exist within or under the storm snow. Expect deep wind slabs in exposed lee terrain and in cross-loaded gullies or terrain features. A recent profile at 1200m in the Shames area showed a thin layer of facets sitting on a crust 35cm off the ground. A snowpack test produced easy results on this layer, but the resistant fracture didn't propagate across the entire column. Total snowpack depth are probably around 150 cm in most treeline areas and deeper but more variable in the alpine. The snowpack below treeline may still be below threshold depth for avalanches in some areas. Check out the Skeena/ Babine discussion forum for more information from the area.

Avalanche Problems

Wind Slabs

Recent strong winds have created deep wind slabs on a variety of aspects. Fresh wind slabs will likely be sensitive to human triggering.
Avoid freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 4

Persistent Slabs

Facet/crust combinations can propagate over large areas, are often prone to remote triggering and step down avalanches, and typical trigger points include thin rocky areas.
Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 5