North Rockies

New snow and wind will build reactive storm slabs. They may be more sensitive on leeward slopes in the alpine and treeline. Uncertainty remains around a buried weak layer in the upper snowpack.

Make conservative terrain choices, particularly with warm temperatures and new load.

Across the northern interior ranges, heavy snow for the North Rockies will prevail Friday night. Up to 25 mm is forecast for the North Rockies with 10 mm for the Cariboo and North Columbia. Note that the North Columbia will receive the bulk of its precipitation on Saturday as the front slides south. Winds will be 30-40km/h with gusts to 50. 

Thursday Overnight: Snow 10 cm. Alpine temperatures -10 and freezing levels valley bottom. Strong westerly winds. 

Friday: Snow amounts 15-20 cm. Freezing level rising to 1500 m. Alpine temperature near -5 with strong westerly winds. 

Saturday: Snow 10-15 cm. Freezing level rising to 1500 m and alpine temperatures near -5. Strong West wind. 

Sunday: Flurries. Freezing level valley bottom and alpine temperature near -10. Moderate Southwest wind.    

Reactive storm slabs are likely on Friday. 

No new avalanche observations were reported on Thursday.

The last persistent slab avalanche associated with the late January surface hoar layer occurred on February 7th in the south of the region. These natural avalanches occurred on a shaded aspect below treeline. A lot of uncertainty exists with this avalanche problem, though it may be unlikely to trigger by the weight of a skier or sledder it may wake up with the warming and new snow load. 

Up to 30 cm of recent storm snow has blanketed a widespread crust. The new snow is expected to bond poorly to the crust. This 1-20 cm thick crust exists on all aspects and elevations, excluding areas in the high alpine in the south of the region that may remain crust-free.

Below the crust, last week's 30-50 cm of storm snow buried a weak layer formed in late January. This layer consists of faceted snow, a melt-freeze crust, and surface hoar crystals in sheltered areas. This layer of buried surface hoar is becoming increasingly hard to find in the snowpack. Our field team was able to find this layer in the Pine Pass area in sheltered areas between 1250-1500 m, their full report can be seen here. Currently, this layer is bridged by a thick surface crust in most areas but will be on our radar with a significant amount of warming and new load. 

The lower snowpack is generally strong and well-bonded. The base of the snowpack is expected to be weak and faceted in shallow, rocky slopes east of the divide.

• Use increased caution at all elevations. Storm snow is forming touchy slabs.
• Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Continue to make conservative terrain choices while the storm snow settles and stabilizes.