Avalanche Forecast

Issued: Dec 25th, 2021 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs.

Avalanche Canada astclair, Avalanche Canada

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Cold temperatures are expected to prolong a poor bond between the old and new snow. Keep in mind that cold temperatures can also increase the consequences of an incident. Enjoy the winter wonderland in low consequence, wind-sheltered areas. 

Summary

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength. Recent weather patterns have resulted in a high degree of snowpack variability within the region.

Weather Forecast

Cold, Arctic air and north winds take the reins

Saturday night: Mostly cloudy, isolated flurries with trace accumulations, winds becoming north and decreasing to light, treeline low temperatures near -13 C, freezing level at sea level. 

Sunday: Mix of sun and cloud, no new snow expected, light north winds, treeline high temperatures near -15 C, freezing level at sea level.

Monday: Mix of sun and cloud, no new snow expected, winds becoming northwest and increasing to moderate in the afternoon, treeline high temperatures near -13 C, freezing level at sea level.

Tuesday: Mainly clear, a trace of new snow possible, moderate north winds, treeline high temperatures near -12 C, freezing level at sea level. 

Avalanche Summary

On Friday, we received several reports of touchy conditions in the North Shore Mountains. The new snow was sliding easily on a rain crust on steep terrain features. Check out these MIN reports from near Hollyburn, Pump Peak, Brockton Point early and Brockton Point in the afternoon for great descriptions and photos of these conditions. 

Snowpack Summary

Since Friday, the mountains picked up another 25-40 cm of cold, light snow. Slab avalanches may remain sensitive to triggering where the new snow has been drifted by wind or where it remains poorly bonded to the old snow. Cold temperatures will likely delay how long it takes for the new snow to form a bond with previous surfaces, which include preserved powder and wind-packed snow at upper elevations and a rain crust near and below treeline. 

Moderate to strong south winds have had an ample supply of light, cold snow to drift into reactive slabs. Winds are forecast to shift to the north and decrease to light, which may have the potential to create an unusual cross-loading or reverse-loading pattern in wind-exposed areas. Start simple and gather information as you go. Monitor for changing slab conditions as you move into wind-exposed terrain and assess the bond of the new and old snow interface. Seek out softer conditions in wind-sheltered areas. 

In the north of the region, a concerning layer of facets (sugary snow) can be found down 100-200cm over a crust that formed in early December. This layer is slowly transitioning from stubborn to unreactive as the snow above stiffens and makes it harder to trigger. This problem is particularly hard to predict and tricky to manage. Get more details and photos in our forecaster blog

Be sure to watch this week's snowpack summary video from North Shore Rescue

Terrain and Travel

  • Give the new snow time to settle and stabilize before pushing into bigger terrain.
  • Be alert to conditions that change with elevation and wind exposure.
  • Make observations and assess conditions continually as you travel.
  • Use small low consequence slopes to test the bond of the new snow.
  • Even a small avalanche can be harmful if it pushes you into an obstacle or a terrain trap.

Problems

Storm Slabs

An icon showing Storm Slabs

Since Friday, 25-40 cm of new snow has accumulated, forming a widespread storm slab problem that may remain reactive to human triggering. Strong south winds during the storm have likely built larger, more sensitive slabs in wind-drifted areas at upper elevations. Cold temperatures mean that the new snow could take more time than usual to bond with the previous snow surface. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1.5 - 3

Valid until: Dec 26th, 2021 4:00PM