Avalanche Forecast

Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Monday night: Mostly cloudy with flurries, moderate southwest wind with strong gusts, treeline low around -8 °C, freezing level below valley bottom.

Tuesday: Cloudy, 5 cm new snow, strong southwest wind, treeline high around -3 °C, freezing level rising to 700 m. 

Wednesday: Cloudy, 20-30 cm new snow, strong southwest wind, treeline high around +1 °C, freezing level rising to 1000 m. 

Thursday: Mostly sunny, trace of new snow, light southwest wind, treeline high around +4 °C, freezing level rising to 2600 m.

On Sunday, explosives triggered several avalanches of size 2 to 3. A few of these were persistent slab avalanches and released on the early December layer.

On Saturday, numerous storm slabs up to size 2.5 were triggered by explosives. 

A natural avalanche cycle to size 2 occurred overnight Thursday-Friday with accumulating snowfall and wind. On Friday morning, explosives easily triggered storm slabs to size 2.5. Several natural slab avalanches of size 2 and one size 3 released naturally. 

There has been an alarming pattern of large, persistent slab avalanches being consistently reported over the past two weeks. Almost all of these avalanches ran on the early December weak layer. Deeply buried persistent problems like these don't go away overnight, and it remains a serious concern. 

• On Sunday, a few size 2 to 3 persistent slab avalanches were triggered by explosives. One avalanche released at 1900 m and was more than 1 m deep and 150 m wide. 
• On Saturday, a large (size 2.5) persistent slab avalanche was triggered by explosives on the early December layer that was reloaded with new snow.
• On Friday, a natural persistent slab avalanche of size 3 released 1-2 m deep on the early December layer at 2100 m on an E aspect in the north of the region. A size 2 persistent slab avalanche occurred naturally and failed on the same layer 30 cm deep. The feature had slid previously, and new snow reloaded the persistent weak layer.
• On Tuesday, explosive control work near Rossland produced a size 2.5 persistent slab avalanche on a layer of surface hoar from late December. 
• On Monday in the neighbouring South Columbia region, a natural size 2.5 persistent slab avalanche was reported on a NE aspect at 2200 m failing 80 cm deep on the early December layer.
• A few notables from last week feature in our latest blog Photos of recent persistent slab avalanches in the southern interior. 

15-30 cm of recent storm snow fell with southwesterly wind and warming temperatures, resulting in a denser slab forming over lower density snow. An accumulated total of 60-80 cm of new and recent snow now sits over variable and potentially weak snow surfaces including widespread facets, wind affected snow, and/or surface hoar up to 5 mm in sheltered areas.

The early December crust/facet layer has been responsible for sporadic but very large, persistent slab avalanches over the past two weeks. The crust is now buried 120-200 cm deep except in thin, wind affected areas near ridgetops where nearly all of the recent avalanches have been triggered. 

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• Be aware of the potential for large avalanches due to the presence of a persistent slab.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.