Avalanche Forecast

Issued: Dec 25th, 2016 4:07PM

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

Avalanche Canada cgarritty, Avalanche Canada

Keep the wind slab problem in mind as you enjoy one more day of relatively good stability. New snow is coming!

Summary

Confidence

Moderate - Timing of incoming weather systems is uncertain on Monday

Weather Forecast

Monday: Periods of snow delivering 10-20cm with greater depths in the south of the region. Winds will be moderate gusting to strong from the southwest. Freezing level to approximately 700 metres with alpine temperatures of -8 in the north and closer to -2 in the south.Tuesday: Flurries in the north of the region delivering 5-10cm of new snow with 25cm of new snow expected in the south. Winds moderate gusting to strong from the southwest. Freezing levels to about 900 metres with alpine temperatures of -7 in the north and -2 in the south.Wednesday: Flurries delivering a trace of new snow in the north of the region and up to 10 in the south. Winds moderate gusting to strong from the southwest. Freezing levels to approximately 600 metres with alpine temperatures to -9 in the north and -5 in the south.

Avalanche Summary

Continued potential exists for skier and rider triggering of wind slabs at upper elevations. The possibility of buried surface hoar in isolated sheltered areas and a possible weak bond at the storm/old snow interface also demand careful evaluation. A MIN report from Saturday in the Pemberton Icefield area neatly demonstrates the potential for wide slab propagations on wind loaded features.

Snowpack Summary

A layer of 3-5mm surface hoar has grown on the surface in the Duffey Lake area. Below this, 10-20cm of new snow fell over Thursday and Friday. This new snow has been redistributed in some exposed areas and added to the 30-60cm of storm snow the region has seen since Sunday. In higher elevation and exposed areas, this storm snow formed wind slabs in response to southwest winds. The new snow and wind slabs overlie a variable snow surface from last week that includes hard wind pressed or scoured areas, old wind slabs, weak faceted snow, or surface hoar. 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.

Problems

Wind Slabs

An icon showing Wind Slabs
Thin pockets of wind slab are lingering in lee terrain and remain sensitive to human triggers. Evaluate slopes carefully as you move through different aspects and elevations.
Be cautious as you transition into wind affected terrain.Watch for signs of instability such as whumpfing, or cracking.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 26th, 2016 2:00PM

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