Avalanche Forecast

Moderate - Uncertainty is due to whether buried persistent weak layers become active, triggering avalanches, with the arrival of the forecast weather. Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather systems in the south coast and south coast inland are fast moving and weather models are changing. A third significant storm is now forecast to impact the region for Sunday night into Monday and the intensity of Saturday night's storm has eased.  

Friday night: Periods of snow with up to 15cm new snow (& rain), wind moderate southwesterly gusting extreme, alpine low -0C, freezing level rising to 1200m.  

Saturday: A mix of snow and rain, with 5-10cm new snow (5--10mm rain), moderate southwesterly ridge top winds gusting strong, alpine high +2C, freezing level 1500m.

Sunday: A mix of snow and rain, with 5-15cm snow (5-15mm rain), moderate southwesterly ridgetop wind gusting strong, alpine high +2C, alpine low 0C, freezing level 1700m.

Monday: A mix of snow and rain with heavy accumulation of up to 60cm, light and variable ridgetop wind gusting strong, alpine high +3C, alpine low -2C, freezing level rising to 2100m.

Limited observations from this region have been reported during the previous days of stormy weather. Ongoing snow fall with moderate to strong rigecrest winds will maintain heightened avalanche conditions over the day Saturday in the Coquihalla Pass area. In other regions (near Manning Park and in the Duffy) less overall snowfall and wind values will keep hazard considerable.  

On Thursday a MIN from the Coquihalla pass area reported sticking to low angle terrain but still report being to intentionally trigger small avalanches on low hazard test slopes. These indicator avalanches were reported in alpine wind affected terrain and ran on the crust down about 20-30cm.  

On Wednesday there were numerous reports of avalanches from the MINs. From the north comes this MIN from the Hurley where this groups triggered 2 small avalanches at around 1700m that were 35cm deep on a crust, This MIN from south of the Coquihalla pass reports a large accidentally triggered avalanche 60cm deep on a southeast aspect in the alpine. On the same day, this MIN reports observing sensitive wind slabs in the lee well below the Ridgecrest in addition to some sudden "pop" results in test pits.

Have you been out and about in the mountains? If so please submit your observations to the Mountain Information Network (MIN). It doesn't have to be technical - photos are especially helpful! Thank you so much for all the great MINs submitted so far! 

Another 10-15cm forecast overnight Friday with moderate to strong southwest ridgetop winds will continue the pattern of incremental loading with significant wind redistribution and wind-loading in lee features. Strong southwesterly winds have formed windslabs in the alpine, at ridgecrest and in lee features.  

A rain crust from the first week of December is down 55-75cm and remains the chief layer of concern in this area. It continues to produce intermittent test results and we are curious how it will react to additional snow loads. Depths of these buried weak layers varies across the region: In the Duffy and Manning park they sit under about 50cm of snow while at the Coquahalla Pass they lie buried under 60-75cm.     

On Thursday, this MIN from 1550m at an open glade near Box canyon reports a moderate sudden "Pop" 50 cm down on the surface hoar layer with some great photos.  

In the north of the region, a crust/facet layer sits near the ground. The most recent avalanche activity observed on this layer was on December 1st when a natural cornice fall triggered a size 3. More recent snowpack tests in the Cayoosh zone found this layer down 100+ cm and unreactive. While our uncertainty around the reactivity of this crust is keeping it on the radar going into the active weather pattern over the next week or so, it does not appear to be an active problem at this time.

• Minimize exposure during periods of heavy loading from new snow and wind.
• Storm snow and wind is forming touchy slabs. Use caution in lee areas in the alpine and treeline.
• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.