Avalanche Forecast

Issued: Dec 16th, 2021 4:00PM

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

Avalanche Canada bchristie, Avalanche Canada

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Carefully evaluate conditions before stepping into big, open, or steep slopes. Back off if you find signs of instability like shooting cracks, whumpfing noises, or recent avalanches. 

Summary

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

A clear period gives way to moderate snowfall for Saturday at all elevations as freezing levels remain low. We'll see another shift in wind direction starting Sunday with the potential for the windspeed to be highest at lower elevations.

Thursday Night: Clear. No new snow expected. Light southwest wind. Treeline high around -13 °C, with a temperature inversion. Above 2000m temperatures will rise above -10 °C.

Friday: Increasing cloud cover. Snowfall beginning late afternoon. Winds becoming moderate southwest. Treeline high around -14 °C.

Saturday: Overcast. 2-10 cm of snow expected overnight, and another 0-5 cm through the day. The higher amounts are forecasted for the south of the region. Moderate to strong southeast winds, trending to southwest at higher elevations. Treeline high around -12 °C.

Sunday: Mostly clear. No new snow expected. Moderate east winds, trending to northeast at higher elevations. Treeline high around -12 °C.

Avalanche Summary

Wind slabs formed on all aspects in exposed terrain are expected to remain sensitive to human triggers.

On Wednesday, one isolated size 2 avalanche was reported in the far south of the region, possibly started by a cornice fall. 

On Monday, the Avalanche Canada field team reported a few size 1 loose dry avalanches on steep alpine slopes. 

Snowpack Summary

Given the variable nature of the recent wind, slabs should be expected on all aspects in exposed terrain. 

Check out this post on the Mountain Information Network (MIN) from our Northwest field team for a great summary of conditions at Hankin-Evelyn on Thursday. 

Over the weekend, the region typically saw 10-20 cm of new snow. This new snow was accompanied by strong SW winds which formed reactive wind slabs in exposed terrain. On Monday, some areas of the region may have had outflow (NE-E) winds which may have formed wind slabs on south and west aspects. 

An early season crust and facets can be found near the base of the snowpack. This layer now appears to have gone dormant through most of the region but could still be reactive in some shallow snowpack areas. 

Snowpack depth at treeline typically ranges from 100-200 cm, with higher values in the western part of the region and tapering to the east. In the far southwest of the region, the height of snow is closer to 300 cm. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be alert to conditions that change with elevation and wind exposure.

Problems

Wind Slabs

An icon showing Wind Slabs

Given the shifting nature of the recent winds, wind slabs should be expected on all aspects in exposed terrain. 

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Dec 17th, 2021 4:00PM