Avalanche Forecast

A series of frontal systems coming in off the coast will bring light precipitation throughout the week.

Wednesday Overnight: Partially cloudy in the north, mainly clear in the south. Freezing level dropping to valley bottom. Light southwest winds. 

Thursday: Cloudy with snowfall, 5-15 cm of accumulation. Freezing level rising to 1500 m. Moderate to strong southwesterly winds. 

Friday: Cloudy with snowfall, 5-10 cm of accumulation. Freezing level rising to 1500 m in the afternoon. Light to moderate southwesterly winds.

Saturday: Mainly cloudy, light flurries. Freezing level around 1000 m. Light to moderate southwesterly winds. 

On Tuesday, numerous natural and skier-triggered storm slabs were reported throughout the region. The larger and more consequential avalanches failed on the old surface, where surface hoar or a crust was present below. 

A few persistent slab avalanches have occurred in the past 3 days in the Valhalla Range, Goat Range, and Lumby Mabel Lake area. These avalanches occurred on one of the facet/crust layers in the upper meter of the snowpack. The report from Park Mountain can be seen here. This MCR (mountain conditions report) from last week in the Valkyr Range echos the uncertainty and complexity surrounding these weak layers.

A very large deep persistent avalanche was reported on Tuesday by an operator in the Selkirks south of Glacier National Park. This avalanche occurred on a south aspect in the alpine and the failure plane is unknown.  

Continued light precipitation will add to 30-60 cm of recent settling storm snow at treeline and above. Storm snow tapers rapidly below treeline, where moist snow or a melt-freeze crust can be expected from rain and warm temperatures.

This new snow is sitting on various surfaces, including hard wind-affected snow, sun crusts on southerly slopes, facetted snow, and isolated pockets of surface hoar. The new snow is bonding poorly to this old surface, especially where a facet/crust layer or surface hoar is present below.

The late February persistent weak layer combination of crust, facets and surface hoar is down 40-50 cm. Two additional persistent weak layers from late January and mid-February are down 80-120 cm. They both consist of surface hoar and/or melt-freeze crusts. These layers are most concerning during periods of new loading, strong solar radiation, or significant warming. 

• Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Be especially cautious as you transition into wind affected terrain.
• Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.