Avalanche Forecast

A shift in the weather pattern is expected from Saturday on. Continued snowfalls, rising temperatures, and back-to-normal winds are expected up to Tuesday. 

Saturday night: Cloudy with flurries up to 5 cm. Freezing level returning to valley bottom. Alpine temperatures around -8C. Strong southerly winds up to 60 km/h.

Sunday: Snow 5-10 cm. Freezing level rising to 1400 m. Alpine temperatures around -6 C. Strong southerly winds up to 60 km/h.

Monday: Snow 10-15 cm. Freezing level rising to 1400 m. Alpine temperatures around -4 C. Moderate southerly winds gusting 50 km/h.

Tuesday: Snow 5-10 cm. Freezing level rising to 1600 m. Alpine temperatures around -2 C. Moderate southerly winds gusting 50 km/h.

Friday, two massive natural cornice falls were observed in the region. One of them triggered a very large (size 3) persistent slab avalanche just outside Valemount on a south-facing alpine slope. The other cornice fall had debris the size of a very large truck. This evidence is showing that a large amount of snow is still easily being transported. It also highlights the fact that persistent slabs remain a concern in this region, although a large load is required to trigger an avalanche. 

Last week's extensive northerly winds have created heavily wind-affected surfaces in exposed areas and wind slabs in lee areas. Continued cold temperatures have transformed surface conditions since the latest snow (20-100 cm), about a week ago. A thin sun crust was observed on steep south-facing slopes at lower elevations. Large feathery surface hoar crystals have also been observed in sheltered areas on all elevations. Below ~1200 m, 15-25 cm of snow is now overlying a thick melt-freeze crust. 

Up to 120 cm now overlies a weak layer formed in mid-February. This layer is comprised of surface hoar in sheltered areas, 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. The late-January surface hoar/crust layer is now down 50-150 cm in the snowpack. During the last week, there was isolated reactivity on these layers. We will keep monitoring their reactivity as the next series of snowfalls will affect the region.

• Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
• Wind slabs are most reactive during their formation.
• Closely monitor how the new snow is bonding to the old surface.
• If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.