Avalanche Forecast

MONDAY NIGHT: Cloudy with snowfall, accumulation 25 to 35 cm in the south of the region and 10 to 15 cm in the north of the region, moderate to strong southwest wind, alpine temperature -3 C, freezing level rising to 1400 m over the night.

TUESDAY: Cloudy with snowfall, accumulation 30 to 50 cm with the highest amounts around Coquihalla, strong southwest wind, alpine temperature -3 C, freezing level 1500 m.

WEDNESDAY: Morning snowfall and afternoon clearing, accumulation 5 to 10 cm, light west wind, alpine temperature -10 C, freezing level 500 m.

THURSDAY: Clear skies, light northwest wind, alpine temperature -12 C, freezing level below valley bottom.

On Sunday, storm slabs were reported as being touchy and having surprisingly wide propagation in the central to southern part of the region. They were most touchy on lee slopes at treeline and alpine elevations. Many natural avalanches released within the recent storm snow.

Large persistent slab avalanches continue to be triggered naturally, by humans, and explosives, releasing on the weak layers described in the snowpack summary. Recently the avalanches were 50 to 70 cm thick and released on all aspects between 1800 m and 2300 m. Some of the avalanches sympathetically triggered other avalanches, suggesting the potential for wide propagation.

Avalanche activity is expected to increase through the night and on Tuesday as the storm snow accumulates. Storm slab avalanches will be very likely to be triggered and they may step down to deeper weak layers in parts of the region, forming very large avalanches.

Monday night and Tuesday's storm is forecast to drop 50 to 80 cm of snow across the region, with the highest amounts around Coquihalla. The snow will fall with strong southwest wind and be accompanied with a rise of freezing level to around 1500 m. Below the rain-snow line, loose wet avalanches may prevail. Above the rain-snow line, storm slab avalanches will grow rapidly and likely be very touchy.

Deeper in the snowpack:

• The snow may load a touchy weak layer of feathery surface hoar in sheltered areas above 1800 m. Areas such as Manning, Henning, Stoyoma, Duffey, and Hurley should be treated as suspect.
• A persistent weak layer is present near the bottom of the snowpack in the northern half of the region (e.g., Duffey, Hurley). The weak layer of sugary faceted grains exists around a hard melt-freeze crust from mid-November, which is an indicative snowpack setup for large and destructive avalanches. The likelihood of natural and human-triggered avalanches on this layer remains elevated with the snow and wind loading occurring during this stormy period.
• There are currently no deeper concerns near Coquihalla summit.

• Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
• If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.
• Avoid traveling in runout zones. Avalanches have the potential to run to the valley floor.