Avalanche Forecast

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 5-10 cm. Freezing level rising to 1800 m. Alpine temperature near -5 with strong westerly winds. 

Saturday: Snow 10-20 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.    

Storm slabs will likely be touchy on Friday. 

On Wednesday, several wind slabs and storm slab avalanches were reported up to size 2. These failed in the recent storm snow and didn't step down to deeper layers. 

On Tuesday, a natural cornice fall triggered a persistent slab size 2.5 from an East aspect at 2000 m. This was said to be approximately 72 hours old. 

Last Friday, sledders near Blue River remote triggered several large slab avalanches on shaded aspects at treeline. The failure plane of these avalanches is uncertain, but large remote triggered avalanches would make us suspect it failed on the late January buried surface hoar. Photos from this incident can be seen here.

15-30 cm of recent storm snow is expected to bond poorly to the old surface. This surface is comprised of near-surface faceting, surface hoar growth overlying a melt-freeze crust at lower elevations, a sun-crust on steep solar aspects, and hard wind-affected snow in the alpine and exposed treeline. 

Digging deeper in the snowpack exists another weak interface of primarily surface hoar/crust now buried up to 100 cm. This is on our radar. Reports suggest that the surface hoar is most prominent in sheltered openings at and below treeline. Terrain features to be suspect of includes the lee side of protected ridges, openings in the trees, cut blocks, and burns. Concerns are that new snow loading and warming may wake this weak layer up, initiating surprisingly large avalanches.  

The lower snowpack is generally strong and well-bonded.

• 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 surface hoar.
• Surface hoar distribution is highly variable. Avoid generalizing your observations.