Avalanche Forecast

THURSDAY NIGHT: Cloudy with flurries, up to 5 cm snow accumulation, moderate southwest wind, alpine temperature -10 C, freezing level below valley bottom.

FRIDAY: Cloudy with snowfall, accumulation 15 to 30 cm with highest snowfall amounts in the Coquihalla area, moderate to strong southwest wind, alpine temperature -8 C, freezing level at 500 m.

SATURDAY: Cloudy with flurries, up to 10 cm accumulation, light southwest wind, alpine temperature -10 C, freezing level at 500 m.

SUNDAY: Cloudy with snowfall, 5 to 15 cm accumulation, light to moderate southwest wind, alpine temperature -12 C, freezing level below valley bottom.

On Wednesday, avalanches were triggered with explosives and ranged from size 1.5 to 2.5. One avalanche of size 3 released on a deeper weak layer in the snowpack and reached a depth of 130 cm. It was triggered by explosives. 

On Tuesday, several natural and skier triggered slab avalanches of size 1 were observed. One wet loose avalanche of size 2.5 was reported. 

On Monday, a natural avalanche cycle occurred during the peak of the storm with avalanches up to size 3.5. Most avalanches released in the storm snow. However, several avalanches released on a deeper weak layer from mid November, predominantly in the north of the region. These avalanches were mostly between size 2 and 2.5.

The storm will bring up to 5 cm of snow overnight and 15 to 30 cm during the day on Friday with the highest snowfall amounts in the Coquihalla area. Combined with moderate to strong southwest wind the deepest and most sensitive slabs will form in lee terrain features. This new snow falls on a variable snow surface which ranges from strongly wind affected to soft deep snow. The new snow will fall with cold temperatures and it is in uncertain how fast it will bond with the old snow surface. The old snowpack has not quite recovered and gained strength from the previous snow storm which had delivered between 30 and 60 cm with higher amounts of snow in the south of the region and mostly rain below 1500 m.

Deeper in the snowpack:

• The snow loaded 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. This is an indicative snowpack setup for large and destructive avalanches. The likelihood of human-triggered avalanches decreases as the layer gets deeper but the consequence of triggering it would be severe.
• There are currently no concerns deeper in the snowpack near Coquihalla summit.

• Storm slab size and sensitivity to triggering will likely increase through the day.
• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches.