Avalanche Forecast
Issued: Nov 30th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
swerner,
Avalanche Canada
Wind slabs on leeward slopes may be reactive to human triggering, especially in steep unsupported terrain features. The afternoon sun may have enough punch to moisten and weaken snow surfaces, especially on steep south slopes. Heads up for changing conditions.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
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High pressure should start to build off the coast on Tuesday bringing a mix of sun and cloud. Wednesday afternoon may see a temperature inversion above 2000 m.Â
Monday Night: Light snow expected up to 5 cm. Strong WNW winds in the alpine.
Tuesday: Mix of sun and cloud. Alpine temperatures near -2. Strong ridgetop winds from the WNW.Â
Wednesday: Mostly sunny with some cloud. Possible alpine temperature inversion bringing warm air above 2000 m. Alpine temperatures near 0 degrees or warmer if the inversion is strong. Freezing levels 2500 m. Ridgetop winds light from the East.
Thursday: Mix of sun and cloud. Alpine temperatures near -2. Ridgetop winds light from the southwest.
Avalanche Summary
No recent avalanche observations have been observed and reported. The most likely problem is wind slabs in steep wind exposed terrain at upper elevations.Â
Please submit your observations to the Mountain Information Network if you've been out and about recently.
Snowpack Summary
Wind slabs have formed on open leeward terrain as last week's 10 to 15 cm of snow was redistributed and formed into more cohesive slabs. Snow surfaces are scoured on windward slopes.Â
Surface snow conditions may change with forecast sunshine and warmer temperatures up high on Tuesday afternoon and Wednesday. Surface snow may be moist and reactive on sunny slopes then re-freeze overnight into a crust.Â
Snowpack depths are variable with reports of 50 to 100 cm in terrain that hasn't been scoured by the wind. There are some reports of a hard crust buried about 30 cm below the surface, which could be a bed surface for wind slab avalanches. There is most likely a crust at the bottom of the snowpack, and there have been a few reports suggesting weak snow may be forming around these crusts. This layer could become a bigger concern when it gets buried deeper.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
- Be alert to conditions that change with elevation and sun exposure.
Problems
Wind Slabs
Watch for freshly formed wind slabs in the alpine, and open "alpine like" features at treeline. These slabs may be poorly bonded to the underlying snow. Surface snow may become reactive with the afternoon sun, especially on steep solar aspects.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 1st, 2020 4:00PM
