Avalanche Forecast

Moderate - Uncertainty is due to how buried persistent weak layers will react with the forecast incoming weather.

One more day of very warm and sunny conditions before the ridge breaks down Sunday night. A weak system is forecast to bring light snowfall Monday morning. 

Saturday night: Clear, light SW-W wind, freezing levels around 2800 m.

Sunday: Mainly sunny, light to moderate SW wind, freezing levels 2000-2800 m. 

Monday: Light snow in the morning, a chance of sunny breaks in the afternoon, light to moderate NW wind, freezing levels 600-1400 m. 

Tuesday: A mix of sun and cloud, light to moderate NW wind, freezing levels reaching around 1500 m. 

On Friday, a natural size 2.5 slab avalanche was observed in the Coquihalla area on a NE aspect at 1900 m which was expected to have been cornice triggered. In the north of the region, explosives triggered numerous cornices up to size 2. Two of these triggered size 2 slabs on the slopes below failing down 40-60 cm. A few loose wet avalanches were observed on steep solar aspects on Thursday and Friday. 

On Wednesday, a natural size 2.5 persistent slab avalanche occurred in the Duffey Lake area on a north aspect at 2200-2300 m which failed down 80 cm on the late-January interface. 

Last weekend, several very large human-triggered avalanches occurred on the late-January persistent weak layer in the north of the region. This layer is now sitting dormant but there is serious concern that it is going to wake up with sun and very warm temperatures this weekend. The layer is down 20-70 cm so it is still in the prime depth for human-triggering. Cornice releases are also a major concern for triggering persistent slabs so give extra caution to overhead slopes which are exposed to cornices. Some avalanche activity also occurred on the layer in the south of the region but the avalanches were generally smaller with less propagation and the layer generally appears to be less reactive in the south.  

A widespread surface crust is reported at all elevations and aspects except for possibly some high elevation polar aspects which may still have some dry snow prior to Saturday in the north of the region. Prior to the warming and sun, strong winds had caused extensive wind effect and wind slab formation in exposed terrain at higher elevations. 

The primary concern in the snowpack is the late-January weak layer down 20 to 70 cm. This layer is primarily composed of a crust and facets, but also may include surface hoar in more sheltered areas around treeline elevation. The interface is most prominent between 1700 and 2000 m in the north of the region and it has been found on all aspects in the Duffey Lake area. This layer is up to around 90 cm deep in the south of the region and while it did produce some avalanches last weekend, it does not seem to be as reactive as it is in the north of the region.

• Be aware of the potential for large avalanches due to the presence of buried weak layers.
• Remote triggering is a concern, avoid terrain where triggering slopes from below is possible
• Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
• Extra caution is needed around cornices under the current conditions.
• Avoid exposure to steep, sun exposed slopes, especially when the solar radiation is strong.