Avalanche Forecast

Moderate -

2-4 cm of new snow is forecast for Sunday overnight with moderate southwest wind in the alpine. Another 2-4 cm is expected on Monday morning with light alpine wind. Sunny breaks are forecast for the afternoon with freezing levels reaching around 1700 m. Tuesday is expected to be mainly cloudy with sunny breaks in the morning and light snow in the afternoon. Alpine wind is forecast to be moderate from the southwest and freezing levels are expected to reach around 1500 m. Similar unsettled conditions are currently forecast for Wednesday with sunny breaks and light snowfall both possible.

A natural size 3 persistent slab was observed on Saturday northwest of Valemount on a north aspect at 2500 m which failed down 50-100 cm. On Friday, a natural size 3.5 avalanche was reported southwest of Valemount on a east aspect at 2600 m. It's not certain how old it was, but it was likely triggered by a cornice or ice fall, stepped down to ground, and destroyed some mature timber. Earlier last week, several size 2.5-3.5 avalanches were triggered naturally and by explosives. This included a natural cornice triggered size 3 avalanche on a northeast aspect, an explosive triggered size 3.5 deep persistent slab that stepped down to the November crust, and a explosive triggered size 2.5 persistent slab that failed on the mid-February crust layer down 120 cm.On Monday, the recent storm snow is expected to be reactive at higher elevations, especially in wind loaded terrain and on steep convex features. Cornices are large and may become weak with daytime warming or during stormy periods. We are in a low probability, high consequence scenario for persistent slab avalanches failing on deep buried weak layers. Click here for more details. Click here for photos the avalanche cycle last week.

20-40 cm of snow has now accumulated over the past week which overlies a rain crust at lower elevations or a sun crust on solar aspects at higher elevations. Alpine wind has recently been strong mainly from south through west directions and has loaded leeward slopes in exposed terrain at treeline and in the alpine. Large cornices are also reported in the alpine. At lower elevations, there may be multiple crust layers in the upper snowpack which are now expected to generally be well bonded and stable. At higher elevations, the February crust/facet layer is down 100-150 cm and woke up during last week's storm with many avalanches stepping down. The deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack and a few avalanches and cornice falls also stepped down to these layers recently resulting in some very large full depth avalanches. Heavy triggers like cornices and explosives continue to sporadically trigger deep weaknesses in the snowpack as recently as Saturday.