Avalanche Forecast

Moderate - Forecast precipitation (either snow or rain) amounts are uncertain. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

A strong pacific system will impact the region on Friday evening, bringing moderate to heavy precipitation and strong winds. Active weather will continue into the weekend, with a clearing trend forecast for early next week.

Friday Overnight: Mixed precipitation, 5-20 cm of new snow accumulation at higher elevations. Freezing level around 1500 m. Moderate to strong southwesterly winds. 

Saturday: Continued snowfall, 5-20 cm of accumulation. Freezing level around 1000 m. Moderate to strong southwesterly winds.

Sunday: A mix of sun and cloud, light snowfall. Freezing level dropping to valley bottom with alpine temperatures around -10 C. Light northwesterly winds.

Monday: Mainly clear. Alpine temperatures plummeting into the -20s. Light northeasterly winds.

As the winds picked up on Thursday, operators in the south of the region reported numerous small skier-triggered wind slabs failing easily on the old hard surface.

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. 

Last weekend, 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.

Continued snowfall throughout Saturday will add to 15-40 cm of recent storm snow above the old surface. This surface is comprised of facetted snow, 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 another weak interface exists of primarily surface hoar/crust now buried up to 120 cm. With new load testing the snowpack, 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. It is possible 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.