Archived

Avalanche Forecast

Dec 21st, 2016–Dec 22nd, 2016

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

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

Regions: South Coast Inland.

As this past week's storm snow continues to settle it will still be important to evaluate the bond between the old snow surface and the new snow. There is still potential for a week sliding layer in isolated sheltered areas.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Thursday: Flurries, accumulation 5-10cm / Moderate southwest wind / Alpine temperature -2Friday: Mainly cloudy with isolated flurries / Light northeast wind / Alpine temperature -5Saturday: Mix of sun and cloud/ Light north wind / Alpine temperature -8

Avalanche Summary

Recent reports in the Duffy Lake area indicate a few natural avalanches running to size 2 in the alpine. I would suspect there to be continued potential for skier and rider triggering with the recent new snow, strong winds at upper elevations and a possible weak bond at the storm/old snow interface the possibility of buried facets or surface hoar in isolated sheltered areas.

Snowpack Summary

30-60cm new snow overlies the previous variable snow surface from last week, which includes hard wind pressed or scoured areas, old wind slabs, weak faceted snow, or surface hoar. New wind slabs that have formed in response to southwest winds. In the Duffey Lake area, recent snowpack tests gave hard sudden results down 60 cm at the interface between the recent storm snow and old snow on rounding faceted crystals. The widespread mid-November crust is typically down approximately 1-1.5m. Recent snowpack tests have shown the crust to be unreactive, but it could become a problem in shallow alpine start zones.

Avalanche Problems

Storm Slabs

30-50cm of new snow sits on a variety of potential weak sliding layers.

Carefully evaluate terrain features by digging and testing on adjacent, safe slopes. Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Wind Slabs

Moderate to strong southwest winds have created wind slabs in the lee of terrain features

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3